Front Weight Jacks
04-19-2014, 11:59 AM
#51
Re: Front Weight Jacks
Tell me that was not fun to watch? You have an idea why I like messing around with a truck- it's the "not expected". My Vette was boring becasue eveyone expects it to be fast. The V6 was fun also becasue it hurt a lot of people's pride on the local circuits, howeve, they'd clean my clock at a drag strip.
04-19-2014, 12:05 PM
#52
Re: Front Weight Jacks
Hi Bian, it does keep within perfect center in limited travel range. I would supect the car would need to travel 6" or more before off centering would be an issue as long as the height is set correctly on the chassis tabs. The problem is the tabs hand so low on the right side.
The Strano Watts (I still say he stole my prototype idea I put up on that Mumford link, and I purposely put it up backwards so if someone tried to steal the idea) and made it a Reverse Watts which does not work when the pivot is on the chassis side and not the axle side. It is fine on smooth roads, but once you put axle articulation into the mix with chassis suspension travel the whole thing goes off into left feild and uncenters itself.
The Strano Watts (I still say he stole my prototype idea I put up on that Mumford link, and I purposely put it up backwards so if someone tried to steal the idea) and made it a Reverse Watts which does not work when the pivot is on the chassis side and not the axle side. It is fine on smooth roads, but once you put axle articulation into the mix with chassis suspension travel the whole thing goes off into left feild and uncenters itself.
04-19-2014, 03:05 PM
#53
Re: Front Weight Jacks
Now because of the reason explained in the last post, one tire on a car will in fact wear out faster than the other three tires- unless you really get lucky and have an exact perfect balance to accept the chamge in fuel load, brake heat fade, and changing track surafce grip and temp in a time duration race five minutes long or more. Yes the car changes in usually just three laps at most on ANY track. The longer the race, the more the change/ So again, usually one tire will wear fater then the other on that side of the car- if it doesn;t, I assure you the next race it will if you change nothing except run a different time of the day.
So what do we do to help prevent this? we try to distribute the weight beter so all four tires accept heat and grip rather than just the outside two. They will not run as hot, and they will last longer. HOWEVER, if you do this too much or the wrong way, the outside tires will load onlly from the side without downward force and you will not have grip (remember the skier and the motorcycle rider. A motorcylce gets better grip on those only two tires by weighting the outside peg of the motorcycle so as to put load down on top of the tire. If the rider weights the inside peg the tires load sideways and loose grip. THIS IS WHY WE DO NOT WNT NEUTRAL ROLL or in other words do not want the rc and cg the same height off the ground. We want a little bit of roll to set the outside tires.
OK, so now you say a lower RC is better then right? NOPE. Why? becasue you need a larger swaybar to counter act the roll force from going too much. Here's my next simple question: why do dofferent cars types require different sway bar sizes and combo's (meaning does a corvette use the same size swabar as a Ferrari, or a Nova? Nope, they all need what is required to control the makeup of the chassis design roll weight....
....Everybody thinks the massive 36 mm front swaybar is the Holly Grail of 3rd gens. That is a massive bar to counteract the deficiancy of such a large positive roll weight the engineers inadvertantly made into these cars. 36 is huge for a street car. Its like the old Chevelles and such running the hugh 1 3/8" performance swaybars to try and somehow contain all that screwed up engineering of the 60's and 70's.
Lets start getting to the point- 1) we want to load the outside tires without using such a parge swaybar that ultimately des nothing more than locks up any independance of individual wheel travel over bumps, and 2) we want to stil weight those outside tires while finding ways to weight the inside tires also to assist heat management of tires and grip.
(here's the punch line)You can have the same exact load on the outside tires with lesser diameter swaybars WHILE ALSO having more load on the inside tires as well.
here is an example: You take (and these are hypothetical but I assure you they are close) two cars the same exact weight, motors, tire size, I mean everything identical twins. You have lets say a cg 16" off the gorund and the forst car has a RA averaging 6" off the ground with 36/24 swaybar combo ( "dynamic" spring rates identical on both cars for sake of ease of examples- note I say dynamic). the second car has lets say extended ball joints, progressive rear springs, shorter sturt towers,.... basically it has all the same type of parts, just altered settings and heights but pretty much everything bolts in the same and is the same weight- so its cg is the same 16" but its RA averages 10"-------------> yes this one only needs a 30/19 swaybar combo..................and BOTH cars roll into a set of 3* chassis angle.
The difference is, if the outside tires take 100% of their capacity (meaning at full grip just before loss of traction, they are both being pressed over with body roll) the car with the smaller swaybars takes more cornering force to get to that 3* roll angle becasue it is carrying more load on the inside wheels then the car with the larger swaybars. The smaller bar car may be carrying 60% of its potential 100% traction, and the other car may be only doing 40% on the inside tires- again while both cars are taking 100% of outside tire grip.
Now this is important- note that if you start taking the rc too high closer to the cg- lets say 16" cg and 12" RA average, the outside tires may not laod on flat ground because the car will maybe only roll to 2* and then loose lateral tire grip and slide. the tires outside tires would only reach about 75% potential grip.
So what do we do to help prevent this? we try to distribute the weight beter so all four tires accept heat and grip rather than just the outside two. They will not run as hot, and they will last longer. HOWEVER, if you do this too much or the wrong way, the outside tires will load onlly from the side without downward force and you will not have grip (remember the skier and the motorcycle rider. A motorcylce gets better grip on those only two tires by weighting the outside peg of the motorcycle so as to put load down on top of the tire. If the rider weights the inside peg the tires load sideways and loose grip. THIS IS WHY WE DO NOT WNT NEUTRAL ROLL or in other words do not want the rc and cg the same height off the ground. We want a little bit of roll to set the outside tires.
OK, so now you say a lower RC is better then right? NOPE. Why? becasue you need a larger swaybar to counter act the roll force from going too much. Here's my next simple question: why do dofferent cars types require different sway bar sizes and combo's (meaning does a corvette use the same size swabar as a Ferrari, or a Nova? Nope, they all need what is required to control the makeup of the chassis design roll weight....
....Everybody thinks the massive 36 mm front swaybar is the Holly Grail of 3rd gens. That is a massive bar to counteract the deficiancy of such a large positive roll weight the engineers inadvertantly made into these cars. 36 is huge for a street car. Its like the old Chevelles and such running the hugh 1 3/8" performance swaybars to try and somehow contain all that screwed up engineering of the 60's and 70's.
Lets start getting to the point- 1) we want to load the outside tires without using such a parge swaybar that ultimately des nothing more than locks up any independance of individual wheel travel over bumps, and 2) we want to stil weight those outside tires while finding ways to weight the inside tires also to assist heat management of tires and grip.
(here's the punch line)You can have the same exact load on the outside tires with lesser diameter swaybars WHILE ALSO having more load on the inside tires as well.
here is an example: You take (and these are hypothetical but I assure you they are close) two cars the same exact weight, motors, tire size, I mean everything identical twins. You have lets say a cg 16" off the gorund and the forst car has a RA averaging 6" off the ground with 36/24 swaybar combo ( "dynamic" spring rates identical on both cars for sake of ease of examples- note I say dynamic). the second car has lets say extended ball joints, progressive rear springs, shorter sturt towers,.... basically it has all the same type of parts, just altered settings and heights but pretty much everything bolts in the same and is the same weight- so its cg is the same 16" but its RA averages 10"-------------> yes this one only needs a 30/19 swaybar combo..................and BOTH cars roll into a set of 3* chassis angle.
The difference is, if the outside tires take 100% of their capacity (meaning at full grip just before loss of traction, they are both being pressed over with body roll) the car with the smaller swaybars takes more cornering force to get to that 3* roll angle becasue it is carrying more load on the inside wheels then the car with the larger swaybars. The smaller bar car may be carrying 60% of its potential 100% traction, and the other car may be only doing 40% on the inside tires- again while both cars are taking 100% of outside tire grip.
Now this is important- note that if you start taking the rc too high closer to the cg- lets say 16" cg and 12" RA average, the outside tires may not laod on flat ground because the car will maybe only roll to 2* and then loose lateral tire grip and slide. the tires outside tires would only reach about 75% potential grip.
I cant really know for sure, Im not sure anyone really does, but i would imagine the CG at the front tires is probably around the camshaft, maybe a little higher. So even with a very extreme 1 inch extended ball joint, the front roll center is still a LONG way from the front CG. Is this small (percentage-wise, MAYBE 10 percent closer to the CG?) difference worth the cost? You had a v6 car with 8" wide tires, so dealing with bump steer and wheel clearance/tire size sacrifices werent a huge problem. I wonder if that's still the case with the v8 cars. I need an LS1....
But what I'm taking from what you're saying is that the goal here is to get the roll center closer to the center of gravity. Too close is bad, but it's also absolutely impossible with these cars to get anywhere near too close in the front. But in the rear the roll center is much higher, much closer to the center of gravity.
We have a situation where the front CG has more leverage on the suspension than the rear, where we need larger sway bars that negatively impact the amount of grip our inside tires can give us while turning. That's because the front roll center is too low.
So the rear roll center is in fact much closer to the CG than the front, but that's not good? You're saying that's bad? I presume it's the imbalance in rollcenter->CG distance front to rear that is the problem, yes? So because of that it is worth it to lower the rear roll center and have to go UP in spring rate and sway bar size (just like we have to in the front of the car due to the low RC) and sacrifice grip on the inside rear tire because this balances the car better front to rear? Even though we're going in the wrong direction with the rear roll center, it improves grip balance?
So raising the roll center helps you run lower spring rates and sway bars and get better mechanical grip and balance the left and right side of the car. But lowering the roll center to keep the front and rear roll centers matched will help you balance the grip from front to rear in the car, yes? So we try to balance the front-rear grip, and then we try to raise the front roll center so we can get smaller sway bars, better left-right grip balance, and more mehcanical grip?
Is this the best area to try to make major improvements in these cars? You know I have a problem with the rear sliding out on corner entry (and mid corner). It's controllable but I cant turn in nearly as sharply or quickly as the other guys out there. (Im VERY uncompetitive. A lot of that is my skills as a driver, but not all of it.) This is because the front rear roll center discrepancies are not allowing hurting the front to rear girp balance. So raising the front RC 1 inch, and lowering the rear roll center 1 inch.... is this considered a big adjustment? Or is this just a necessary band-aid?
I have a big 24mm rear sway bar, I want to go smaller, but it may actually help when I get my PHB bracket. But lowering the rear roll center will cause MORE rear body roll, right? I have upped my rear Konis two clicks of rebound just to see if that would help in the meantime.
The car feels good in corners, when Im just driving it around. But I think the tight courses we have in our venue just really, really dont suit my car. And I would imagine this roll center business is even more problematic for cars that have to constantly take transitions and do them quickly. It really brings out the worst of it.
Last edited by InfernalVortex; 04-19-2014 at 03:15 PM.
04-19-2014, 04:55 PM
#54
Re: Front Weight Jacks
Lets back up and keep this simple. The topic of this thread is about weight jackers. I got into the subject of roll centers and roll axis because basically the use of weight jackers is to play with different spring rates.... while retaining static ride height and changing dynamic set of the chassis.
I then went into explaining the basics of roll centers and how they relate to how the car rolls. Your last comment tells me you are jumping ahead and forgeting the very basic thing I told you is happening to you car on corner entry. You car is cantering on its roll axis and throwing the inside rear chassis up into the air unloading the inside rear tire. Don't try to save the whole world right now, just baby steps in tweaking. Get the canter out as as best you can by one of two things right now. 1) either buy the jegs unit I showrd you and get the rear rc down to reduce canter, OR 2) try stiffer rate front springs to reduce the dynamic dive of the front rc under hard brake cornering to see if the car still turns in decent. An increase of front spring rate will not hurt a very fast responsive car.
I then went into explaining the basics of roll centers and how they relate to how the car rolls. Your last comment tells me you are jumping ahead and forgeting the very basic thing I told you is happening to you car on corner entry. You car is cantering on its roll axis and throwing the inside rear chassis up into the air unloading the inside rear tire. Don't try to save the whole world right now, just baby steps in tweaking. Get the canter out as as best you can by one of two things right now. 1) either buy the jegs unit I showrd you and get the rear rc down to reduce canter, OR 2) try stiffer rate front springs to reduce the dynamic dive of the front rc under hard brake cornering to see if the car still turns in decent. An increase of front spring rate will not hurt a very fast responsive car.
Last edited by SlickTrackGod; 04-19-2014 at 05:00 PM.
04-19-2014, 05:07 PM
#55
Re: Front Weight Jacks
I will also add that every 3rd gen can definately use that jegs unit as well as a full spring change. What springs? Depends on each individual car and is figure out only with testing (trial and error). The jegs unit is definately a need- if not right now then definately in the future to get the car more sorted. Jegs unit should be purchased before weight jackers unless restricted by racing rules. Which way to go is only up to you and where you are ultimately headed.
04-19-2014, 05:35 PM
#56
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Re: Front Weight Jacks
A car can only corner as good as the front - you match the rear to the front. Work out the front first.
As an approximate guess: the stock front RC is 3". Dynamic RC (loaded suspension) would be .5" or zero (soft stock suspension). If you lower the car, it gets worse. Optimal Road Race Fr RC could be anywhere from 1" - 2.5" and -0.5" - +1." for autox.
Some Sutton text:
The forces that act on the car to make it roll … when a car is cornering … … act upon the car’s Center of Gravity (CG). With typical production cars & “most” race cars, the CG is above the roll center … acting like a lever. The distance between the height of the CG & the height of each Roll Center is called the “Moment Arm.” Think of it a lever. The farther apart the CG & roll center are … the more leverage the CG has over the roll center to make the car roll. Excessive chassis roll angle is your enemy, because it is over working the outside tires & under utilizing the inside tires.
Now I’ll throw you a curve ball. The static RC at ride height doesn’t mean much. It is the dynamic roll center “in dive” that really matters. “In dive” means when the front suspension is compressed & the car is in roll. So in the corner … when you have the front suspension compressed & the car is rolled over … all those angles change … and therefore the roll center moves. It typically goes down … and may migrate to the left or right of center.
What are (or can be) your tuning tools to change angles:
1. Spindle heights and/or distances from spindle pin to ball joint surfaces
2. Ball joint pin heights
3. Control arm length*
4. Adjustable control arm mounts on the chassis.
5. Also, obviously, any changes in ride height.
Direction:
a. Raising the RC, places it closer to the CG, reducing the CG leverage, reducing roll angle … and working the front tires less.
b. Lowering the RC, places it farther from the CG, increasing the CG leverage, increasing roll angle … and working the front tires more.
c. For faster corners found at big road courses I’ve found the happy window to be 1” to 2.5” … and -0.5 to 1.0” for tight AutoX events.
d. If the RC migrates to the inside of the corner under dive … it will work the front tires more … but roll more if not controlled by the suspension.
e. If the RC migrates to the outside of the corner under dive … it will roll less work the front tires & roll less.
A lot of stock production cars have the swing arms so far out … there is little to no camber gain … often camber loss. Plus, in many stock production cars the A-arm angles put the roll center so low it is below ground ... and the CG is high … giving it a ton of leverage to roll the car … which is part of why many stock production cars roll so much.
As an approximate guess: the stock front RC is 3". Dynamic RC (loaded suspension) would be .5" or zero (soft stock suspension). If you lower the car, it gets worse. Optimal Road Race Fr RC could be anywhere from 1" - 2.5" and -0.5" - +1." for autox.
Some Sutton text:
The forces that act on the car to make it roll … when a car is cornering … … act upon the car’s Center of Gravity (CG). With typical production cars & “most” race cars, the CG is above the roll center … acting like a lever. The distance between the height of the CG & the height of each Roll Center is called the “Moment Arm.” Think of it a lever. The farther apart the CG & roll center are … the more leverage the CG has over the roll center to make the car roll. Excessive chassis roll angle is your enemy, because it is over working the outside tires & under utilizing the inside tires.
Now I’ll throw you a curve ball. The static RC at ride height doesn’t mean much. It is the dynamic roll center “in dive” that really matters. “In dive” means when the front suspension is compressed & the car is in roll. So in the corner … when you have the front suspension compressed & the car is rolled over … all those angles change … and therefore the roll center moves. It typically goes down … and may migrate to the left or right of center.
What are (or can be) your tuning tools to change angles:
1. Spindle heights and/or distances from spindle pin to ball joint surfaces
2. Ball joint pin heights
3. Control arm length*
4. Adjustable control arm mounts on the chassis.
5. Also, obviously, any changes in ride height.
Direction:
a. Raising the RC, places it closer to the CG, reducing the CG leverage, reducing roll angle … and working the front tires less.
b. Lowering the RC, places it farther from the CG, increasing the CG leverage, increasing roll angle … and working the front tires more.
c. For faster corners found at big road courses I’ve found the happy window to be 1” to 2.5” … and -0.5 to 1.0” for tight AutoX events.
d. If the RC migrates to the inside of the corner under dive … it will work the front tires more … but roll more if not controlled by the suspension.
e. If the RC migrates to the outside of the corner under dive … it will roll less work the front tires & roll less.
A lot of stock production cars have the swing arms so far out … there is little to no camber gain … often camber loss. Plus, in many stock production cars the A-arm angles put the roll center so low it is below ground ... and the CG is high … giving it a ton of leverage to roll the car … which is part of why many stock production cars roll so much.
04-19-2014, 05:40 PM
#57
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Re: Front Weight Jacks
Hi Dean,
With the swivel weight jacks, you get articulation (non-binding). Is there any other benefit? I would imagine that the spring loading forces are the same no matter what through the a-arms loading the tires. Is there any benefit up top other than "feel," not that I'm discounting feel. Is there a roll advantage? - probably not a quicker set, but no bind?
With the swivel weight jacks, you get articulation (non-binding). Is there any other benefit? I would imagine that the spring loading forces are the same no matter what through the a-arms loading the tires. Is there any benefit up top other than "feel," not that I'm discounting feel. Is there a roll advantage? - probably not a quicker set, but no bind?
04-19-2014, 07:30 PM
#58
Re: Front Weight Jacks
As well as articulate to reduce bind with angle, the swivel jacker as do just that....swivel.... The sprong wil want to unwind when compressed so the top mount swivels in a circle rotation manor to facilitate more linear rate gain - thus smoother allowing better mechanical grip. Yes match the rear.to the front.
My method is weighting the inside rear more to causr that corner to be heavier to lift in order to diagonally roll over to the front. Dive is the same objectivr as set, set pertains to the side, dive pertains to both fronts.
My method is weighting the inside rear more to causr that corner to be heavier to lift in order to diagonally roll over to the front. Dive is the same objectivr as set, set pertains to the side, dive pertains to both fronts.
04-19-2014, 09:29 PM
#59
Re: Front Weight Jacks
Lets back up and keep this simple. The topic of this thread is about weight jackers. I got into the subject of roll centers and roll axis because basically the use of weight jackers is to play with different spring rates.... while retaining static ride height and changing dynamic set of the chassis.
I then went into explaining the basics of roll centers and how they relate to how the car rolls. Your last comment tells me you are jumping ahead and forgeting the very basic thing I told you is happening to you car on corner entry. You car is cantering on its roll axis and throwing the inside rear chassis up into the air unloading the inside rear tire. Don't try to save the whole world right now, just baby steps in tweaking. Get the canter out as as best you can by one of two things right now. 1) either buy the jegs unit I showrd you and get the rear rc down to reduce canter, OR 2) try stiffer rate front springs to reduce the dynamic dive of the front rc under hard brake cornering to see if the car still turns in decent. An increase of front spring rate will not hurt a very fast responsive car.
I then went into explaining the basics of roll centers and how they relate to how the car rolls. Your last comment tells me you are jumping ahead and forgeting the very basic thing I told you is happening to you car on corner entry. You car is cantering on its roll axis and throwing the inside rear chassis up into the air unloading the inside rear tire. Don't try to save the whole world right now, just baby steps in tweaking. Get the canter out as as best you can by one of two things right now. 1) either buy the jegs unit I showrd you and get the rear rc down to reduce canter, OR 2) try stiffer rate front springs to reduce the dynamic dive of the front rc under hard brake cornering to see if the car still turns in decent. An increase of front spring rate will not hurt a very fast responsive car.
Are the extended ball joints still worth it if I dont have room to install a bump steer kit?
04-19-2014, 11:18 PM
#60
Re: Front Weight Jacks
With all that said, you do not want a neutral roll setup either where the roll axis and cg are the same. This would never yield any chassis set when cornering. When pertaining to driver feedback, a loss of touch with the car would be felt. Kind of a false security. The car could often sometime have a feeling of "high siding" like a motorcycle will do- this would happen if air got up under it at the wrong moment, or if you hit a bump and unload the chassis just as you were entering a corner, etc. The comfort of a little 'set' in the chassis when cornering is a comfort thing to help a driver judge the amount of grip is left. Now too much of this causes upper polar movement of chassis weight (remember that hood ornament) and will lean abuptly and snap back resulting in 'tossing" the tire lateral grip into traction loss- thus generally a plow condition where the car squeals and understeers.
RC changes are something everyone needs to feel for them self. Youc an not teach it in words, you have to buy the jegs unit and play with it in a few different setting and realize yourself how each little adjustment changes the whole feel of the car.
RC changes are something everyone needs to feel for them self. Youc an not teach it in words, you have to buy the jegs unit and play with it in a few different setting and realize yourself how each little adjustment changes the whole feel of the car.
I need to get my jegs panhard bar adjuster installed so I can play around with my rear RC. This jegs piece is "bolt-in" but I really want to weld it in. Is it necessary to weld it in? Maybe I'm just being too cautious.
04-19-2014, 11:25 PM
#61
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Re: Front Weight Jacks
The website description advises welding too especially if you intend to track or auto-x.
04-20-2014, 12:25 AM
#62
Re: Front Weight Jacks
Dean thanks a million for all your input. I had given up on bothering with weight jacks after reading more through this thread. Seemed like I'd get more benefit for the moeny by going with the PHB bracket and extended ball joints. This gives me a LOT to work with over the next year or two of figuring the car out, but the weight jack situation will be handled. It's still on the list, just not the top of the list.
Are the extended ball joints still worth it if I dont have room to install a bump steer kit?
Are the extended ball joints still worth it if I dont have room to install a bump steer kit?
Infernal- That is a good choice for now. The Jegs relocator give you tunability and is a great addition, the other can wait (jackers). I found a pic of mine- and YES you should weld it. it would scare me not to- a lot of force applied here.
As for extended ball joints and bump steer? Bump comes mainly from a lot of caster. The bump is induced when the arm comes up and back, not just up (with my experience anyways) I think I was fine with extended ball joints with mild caster. I had fairly massive dynamic increase of caster. I started with a stagnant 5.5 on the right. I was very low at 24 3/4" and I had the mid height Hunter Prototype strut mounts (not the full height units- so my ball joint to strut mount distance was shorter than anyone here and rode very close to hitting up underneath (but never did) What I am getting at is: because of the short length and the static angle, the dynamic angle increased more rapidly in geometry and would gain to probably 8 or 9* caster at 1" compression [see pics] I had to shim my outer tierods and actually dropped them enough to induce 1/8" gain at max travel on both sides (1/16" gain on each of toe out. I started with a static 3/32" toe in). I do not think you'll need a bump steer shim kit.
edit: you know, It's been so long I really do not remeber exactly so please do not trust my info. I touch so many different types of cars I really can not remember if the ball joints caused it to go that much toe-in. Maybe I did have to throw another shim in there now that I recall. I think it was that car I had to drill and put a longer bolt into the the outer tierod /spindle. Looking at my 3rd pic I do not think that was the tapered Baer bolt, I think I did replace that with a 1/2" grade 8 bolt and drilled out the taper.
Last edited by SlickTrackGod; 04-20-2014 at 12:35 AM.
04-25-2014, 02:36 PM
#64
Re: Front Weight Jacks
This thread is definitely informative and clearly describes the roll center's affect on our cars' handling.
To add to the discussion, what if one were to change the weight balance of the cars to let's say 50/50 rather than 58/42 (or whatever these cars are stock)? I am guessing that the CG of the front would lower dramatically if say you relocate the battery to the rear, get a fiberglass hood, and install an LS1 engine, etc, etc.. This would mean the front RC would be closer to the CG without even changing anything in the suspension (but the CG would move down closer to the RC, rather than the RC moving up closer to the CG). At this point though, would the car benefit from lowering the rear RC? I guess this would depend on where the CG is at now?
To add to the discussion, what if one were to change the weight balance of the cars to let's say 50/50 rather than 58/42 (or whatever these cars are stock)? I am guessing that the CG of the front would lower dramatically if say you relocate the battery to the rear, get a fiberglass hood, and install an LS1 engine, etc, etc.. This would mean the front RC would be closer to the CG without even changing anything in the suspension (but the CG would move down closer to the RC, rather than the RC moving up closer to the CG). At this point though, would the car benefit from lowering the rear RC? I guess this would depend on where the CG is at now?
04-25-2014, 09:49 PM
#65
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Re: Front Weight Jacks
This thread is definitely informative and clearly describes the roll center's affect on our cars' handling.
To add to the discussion, what if one were to change the weight balance of the cars to let's say 50/50 rather than 58/42 (or whatever these cars are stock)? I am guessing that the CG of the front would lower dramatically if say you relocate the battery to the rear, get a fiberglass hood, and install an LS1 engine, etc, etc.. This would mean the front RC would be closer to the CG without even changing anything in the suspension (but the CG would move down closer to the RC, rather than the RC moving up closer to the CG). At this point though, would the car benefit from lowering the rear RC? I guess this would depend on where the CG is at now?
To add to the discussion, what if one were to change the weight balance of the cars to let's say 50/50 rather than 58/42 (or whatever these cars are stock)? I am guessing that the CG of the front would lower dramatically if say you relocate the battery to the rear, get a fiberglass hood, and install an LS1 engine, etc, etc.. This would mean the front RC would be closer to the CG without even changing anything in the suspension (but the CG would move down closer to the RC, rather than the RC moving up closer to the CG). At this point though, would the car benefit from lowering the rear RC? I guess this would depend on where the CG is at now?
Weight balance of car is nice to achieve, but dynamic weight xfer is what we're trying to control.
Lower car and raise RC - two sides of the same coin.
04-26-2014, 12:32 AM
#66
Re: Front Weight Jacks
Hellzwings- For the most part I will agree with Tedsgrad on this quote. I will be perfectly honest and say I have very limited -to- almost none experience with setting up mid engine cars and have sme experience with rear engine VW's and Porsches (my irst car ever being a 1963 Ghia) as well as the family having several Porsches (356's, 911's and a 930 Turbo) The same basic priciples apply to the Porsches. We use altered strut spindle assemblies to raise the front rc even though it is a rear engine car when lowered. Roll axis and weight bias are ortty much separate things. What is DIFFERENT about weight bias is front and rear spring rates, but the overall roll axis is generally the same. Same goes for my very limited hands on knowledge of Ferrari's. The Lambo Gallardo mid engine cars are notorious for alot of wandering under hard braking with lots of ill front suspension travel and bad scrub (when a heavier driver like myself is in them with an adequate sized passenger..Video attached They get very squirrelly under throttle and brake modulations and are very short wheelbase cars so you need a wide racetrack becase they are unpredictable. It really has nothing to do with weigght bias, but more so with wheelbase and a shorter roll axis.
(Video is a poor angle- I am very tall and do not fit in these cars so I have trouble with pedal work and steering/knee clearance- I do not fit into the Gallardo hardtops even without a helmet.)
Noshow- I posted a pic of my old rear brakes also. They were Wilwood 4th gen kit 4piston with 12.2" 2 pc rotors with a steel hat internal emergency brake setup to match up to the 6piston 13" fronts. That car is long gone though. I also had drilled axle flanges and focused on a very lightweight rearend for low unsprung weight (Alum diff cover, lightweight gears, Auburn pro carrier, Moser Axles lightened, and of course I ran a carbon fiber driveshaft. My Spohn tqarm was heavy ( I should say more normal weight). These pictures were early on in the building of that car. It later evolved with modifications but the pics show the axles asnd the brand new at that time brakes.
04-26-2014, 01:35 AM
#67
Re: Front Weight Jacks
STG, I've been percolating this stuff around in my head for a couple of weeks now...
The more I think about it the more it all makes sense. I still dont know everything, but I make small realizations all the time about this stuff now. My PHB bracket is en route, hopefully it will be on the car within a few weeks.
If I go with extended ball joints, I can get by with a softer spring up front (slightly) and a smaller sway bar (slightly) because the cg has less leverage on the roll center. This suits me perfectly because I have a 34 (not a 36) front sway bar. I should probably get a 36 anyway, but still... It will address that problem. Front springs just ride REALLY hard, they're cut IROC BZY springs which are near the top of the list for firmness. BZZ if they exist would be firmer. It rides HARD, so I think these are at least 600 lbs stock, if not 650. Cut they're higher than that...
I have too big of a bar in the rear, 24mm, and my rear springs are probably a little on the soft side. They are NNL which is middle range. If I lower the rear RC, I can put that larger sway bar to good use, and then I can cut the rear springs more (to balance the ride height with the extended ball joints) and then put the isolator back in to maximize rear spring rate...
Basically, what I already have seems very well suited for this project.
The only problems I'm having are finding dust boots for the extended ball joints. Do you have any experience with that?
This is what Im looking at:
http://daymotorsports.com/proddisp.php?ln=25437
The more I think about it the more it all makes sense. I still dont know everything, but I make small realizations all the time about this stuff now. My PHB bracket is en route, hopefully it will be on the car within a few weeks.
If I go with extended ball joints, I can get by with a softer spring up front (slightly) and a smaller sway bar (slightly) because the cg has less leverage on the roll center. This suits me perfectly because I have a 34 (not a 36) front sway bar. I should probably get a 36 anyway, but still... It will address that problem. Front springs just ride REALLY hard, they're cut IROC BZY springs which are near the top of the list for firmness. BZZ if they exist would be firmer. It rides HARD, so I think these are at least 600 lbs stock, if not 650. Cut they're higher than that...
I have too big of a bar in the rear, 24mm, and my rear springs are probably a little on the soft side. They are NNL which is middle range. If I lower the rear RC, I can put that larger sway bar to good use, and then I can cut the rear springs more (to balance the ride height with the extended ball joints) and then put the isolator back in to maximize rear spring rate...
Basically, what I already have seems very well suited for this project.
The only problems I'm having are finding dust boots for the extended ball joints. Do you have any experience with that?
This is what Im looking at:
http://daymotorsports.com/proddisp.php?ln=25437
Last edited by InfernalVortex; 04-26-2014 at 02:05 AM.
05-02-2014, 12:36 AM
#69
Re: Front Weight Jacks
Thats awesome TVC! I could easily plastidip the pvc black and be done with it... hmmm...
Also, STG, I got that Jegs bracket... now Im not sure where on the bracket i should mount the reinforcing bar. Should i leave the bottom hole accessible? Or should I do it on the bottom since I shouldnt need to go that low? I know it probably varies, but Im not sure what the most prudent place to weld it is since I've got to block at least one of the mounting holes... Im thinking of blocking off the lowest one because that will brace the mount the best and is the most extreme position it can be adjusted to, but Im open to suggestions.
Also, STG, I got that Jegs bracket... now Im not sure where on the bracket i should mount the reinforcing bar. Should i leave the bottom hole accessible? Or should I do it on the bottom since I shouldnt need to go that low? I know it probably varies, but Im not sure what the most prudent place to weld it is since I've got to block at least one of the mounting holes... Im thinking of blocking off the lowest one because that will brace the mount the best and is the most extreme position it can be adjusted to, but Im open to suggestions.
Last edited by InfernalVortex; 05-02-2014 at 02:59 PM.
05-02-2014, 07:27 PM
#70
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Re: Front Weight Jacks
I'm going to ask some easy elementary questions here....
1) If the issue at hand is preventing the rear inside corner from unloading and shifting that weight to the front outer corner when turning, couldn't one minimize this effect by simply upping the rebound adjustment on the rear Konis?
2) For the person who's just getting into suspension modifications (in other words, those of us who don't understand cg, roll centers, etc), does it make sense to ONLY lower the rear springs and leave the front springs at stock height? What I'm getting is that Dean's Camaro benefited from his extremely low front end because everything else was already maxed out and balanced beyond belief. Whereas one of our cars would probably gain a large benefit from lowering the rear end. But lowering the front end seems to be a give and take situation.
3) The Lamborghini video, is that in automatic, sport, or corsa mode? How much of that darty motion you describe would be eliminated with a set of Continental DW or Pirelli tires instead of Kumho? While it does seem like somewhat of a handful, it also looks easy to control (just point and hang on)......Then again, I'm sure driver skill has a huge factor in how the video came out. (I'm always amazed at how Tiff Needel can keep control in seemingly any car when drifting at high speeds.)
1) If the issue at hand is preventing the rear inside corner from unloading and shifting that weight to the front outer corner when turning, couldn't one minimize this effect by simply upping the rebound adjustment on the rear Konis?
2) For the person who's just getting into suspension modifications (in other words, those of us who don't understand cg, roll centers, etc), does it make sense to ONLY lower the rear springs and leave the front springs at stock height? What I'm getting is that Dean's Camaro benefited from his extremely low front end because everything else was already maxed out and balanced beyond belief. Whereas one of our cars would probably gain a large benefit from lowering the rear end. But lowering the front end seems to be a give and take situation.
3) The Lamborghini video, is that in automatic, sport, or corsa mode? How much of that darty motion you describe would be eliminated with a set of Continental DW or Pirelli tires instead of Kumho? While it does seem like somewhat of a handful, it also looks easy to control (just point and hang on)......Then again, I'm sure driver skill has a huge factor in how the video came out. (I'm always amazed at how Tiff Needel can keep control in seemingly any car when drifting at high speeds.)
05-02-2014, 09:58 PM
#71
Re: Front Weight Jacks
Also, STG, I got that Jegs bracket... now Im not sure where on the bracket i should mount the reinforcing bar. Should i leave the bottom hole accessible? Or should I do it on the bottom since I shouldnt need to go that low? I know it probably varies, but Im not sure what the most prudent place to weld it is since I've got to block at least one of the mounting holes... Im thinking of blocking off the lowest one because that will brace the mount the best and is the most extreme position it can be adjusted to, but Im open to suggestions.
You will know by feel which hole you should be in. Drop it one hole at a time and go test drive the car until you don;t like the feel- then put it back up one hole.
05-02-2014, 10:39 PM
#72
Re: Front Weight Jacks
I'm going to ask some easy elementary questions here....
1) If the issue at hand is preventing the rear inside corner from unloading and shifting that weight to the front outer corner when turning, couldn't one minimize this effect by simply upping the rebound adjustment on the rear Konis?.
1) If the issue at hand is preventing the rear inside corner from unloading and shifting that weight to the front outer corner when turning, couldn't one minimize this effect by simply upping the rebound adjustment on the rear Konis?.
2) For the person who's just getting into suspension modifications (in other words, those of us who don't understand cg, roll centers, etc), does it make sense to ONLY lower the rear springs and leave the front springs at stock height? What I'm getting is that Dean's Camaro benefited from his extremely low front end because everything else was already maxed out and balanced beyond belief. Whereas one of our cars would probably gain a large benefit from lowering the rear end. But lowering the front end seems to be a give and take situation..
3) The Lamborghini video, is that in automatic, sport, or corsa mode? How much of that darty motion you describe would be eliminated with a set of Continental DW or Pirelli tires instead of Kumho? While it does seem like somewhat of a handful, it also looks easy to control (just point and hang on)......Then again, I'm sure driver skill has a huge factor in how the video came out. (I'm always amazed at how Tiff Needel can keep control in seemingly any car when drifting at high speeds.)
The Lambo Gallardos are a very short wheelbase car so drifting in them is as easy as driving a gokart- the longer the wheelbase the more difficult a car is to drift. They also have tons of power so you can modulate them sideway no problem at speed as you see me come off every corner.
The Kumho tires are not the problem, the Gallardo's have a reputation for wandering. it is inherent in the front suspension design under hard slow speed braking with lots of chassis attitude change. The courses we set up are in Autox parkinglots and are notorious for bad pavement bumps on slow tight corners. Higher speed stuff on smooth racetracks is not as much an issue. I have driven the new 2013 Bicolor with the new factory tires on it and it does the same as the 2011 spyder you see us in the video. The Ferrari's are much smoother cars ont he same pavement they look effortless. I actually run faster laps int he ferraris even though it looks slower becasue the car is much more smooth. I do not have video of me in the Scuderia f430 but that car is a handful on a short track in race mode. I purposely leave it in sportmode even if the owner allows me to go into race mode because it is too much car at those low speeds coming off tight corners. If sport moe the Scud barks the tires and just engulfs you off the corners- and yes it will come around even in Sport mode as many instructors get lectured to put the cars back into wet mode. I am one of few they allow to run in sport mode with clients because of my high HP resume and proven ability form past racing history. Most instructors are picked up locally as autox veterans at the local levels, but most are only experienced in Miata's and such- so these cars are eye openers for most of them.
Compare how smooth a F430 is. This is sport mode. I can paddle down, to get off a corner quicker, but not up. The lastest track we did was much tighter and the cars were laging so I would toggle it off two of the corners not to lag. The F430's really can handle race mode on these tracks (except for the Scud as stated earlier) but again, the owner does not allow me to paddle in front of the clients because then they want to do it. All I am doing is giving them a little better show then what they can do- that is what they are paying for. the video takes awhile to get started becasue they clear the course first of slower cars- We do not like to stop with a client on board as a passenger gives them time to feel they are being held up and want a refund- or extra laps.
05-02-2014, 10:55 PM
#73
Re: Front Weight Jacks
Also Reid, Here is one of IL's prodrive instructors back in NewJersey where the company is from- he is in the same exact car so you can compare driving skills and throttle modulation..or should I say lack of. The guy is very timid on the throttle
05-03-2014, 08:40 AM
#74
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Re: Front Weight Jacks
3) The Lamborghini video, is that in automatic, sport, or corsa mode? How much of that darty motion you describe would be eliminated with a set of Continental DW or Pirelli tires instead of Kumho? While it does seem like somewhat of a handful, it also looks easy to control (just point and hang on)......Then again, I'm sure driver skill has a huge factor in how the video came out. (I'm always amazed at how Tiff Needel can keep control in seemingly any car when drifting at high speeds.)
Seriously, I'd have to tell people to go faster most of the time. Get on the straight, "OK now floor it!" and they'd hit the gas for a second and let off. We we got to drive, we left all the nannies on as is. Try and get on the throttle a bit early coming out of a turn, and power wouldn't come on until the steering wheel was straight. Kind of underwhelming but hey at least I can say I drove a Ferrari and a Lamborghini!Pat
05-06-2014, 10:10 PM
#75
05-21-2014, 11:35 AM
#76
Re: Front Weight Jacks
I was talking to a buddy of mine at work who reminds of Dean lol.. Suspension guru type guy.. He was saying that to control the rear roll from lowering the roll center it would be better to bump up compression on the rear shocks to control that roll, rather than to go with stiffer springs. Dean, what is your take on this?
05-21-2014, 04:28 PM
#77
Re: Front Weight Jacks
I was talking to a buddy of mine at work who reminds of Dean lol.. Suspension guru type guy.. He was saying that to control the rear roll from lowering the roll center it would be better to bump up compression on the rear shocks to control that roll, rather than to go with stiffer springs. Dean, what is your take on this?
Shock valving only plays a part in coner entry, corner exit, acceleartion or deceleration (or any of the two above combined).
Generally to reduce nose dive "rate" of the front suspension (under braking)you would increase compression valving if you decrease spring rate- and vica versa. What is not changing is the amount of overall travel- only the time it takes to get to that ultimate travel is what changes in shock valving.
so now lets look at the rear. The two things rear compression vlaving affect is rear loading, and lateral loading. Rear loading is of course acceleration, and lateral loading is the weight going onto the outside wheel under cornering. If you up the compression rate of the rear shock to compensate for lateral loading, (lets say we are turning left), then the RR tire will load more in corner entrance to steady state as the car first lifts off slightly if any straight line braking happens- THEN it will start to load more as the car settles into squat corner set. As this is happening, the car can (if valved right) will compensate for a reduced spring rate ONLY WHEN the shock is settling down in compression stroke towards corner set. Once corner set is reached, the car will not lean on the RR as much and the car will push at steady state....
...Now, as you get back onto the throttle coming off, the weight transfer of the chassis now again stands on the rears ( the RR already loaded) and the wight will rotate off the front onto the LR tire and further tighten the hell out of an already tight /push car at steady state.
Now lets look at what controls body roll+ not compression. THe rebound is what controls body roll. Spring rate controls body roll angle, and copression spring rate controls mainly the wheel movement upward "abruptly" when the wheel hits a bump. In other words, Compression is a false stabilty that only lasts for the moment, where as spring rate is a stable platform to lean on.
Compression should always be valved low. This allows for wheel movement to follow (or conture) to the road surface to maintain mechanical grip. There is always a combined motion ratio of the weight of the car that needs to be addressed through a combination of spring rate + compression valving- so thus the one is in sequence with the other as one dops the other increases (and vice a versa) Spring rate changes have to do with roll center heights.
Get a roll center height too low up front? and the need for heavy srping to control lateral load will cause reduced mechanical straight line braking rip over an imprefect road surface.
Get a roll center too high up front? and the soft springs will not hold up the chassis under extreme braking conditions and thus result in alot of brake dive and suspension travel (as well as a lot of RC migration- which chnages the angle of the overall roll axis front to rear in lateral proportion.
Shock valving is basically the driver's need going into and coming out of corners under hard braking and hard accelerations...period.
Rebound is what controls roll, not compression. It is a much better tool to use to control roll rate, and use springs to control overall roll angle.
05-21-2014, 04:50 PM
#78
Re: Front Weight Jacks
I should not talk about this stuff- so I will change things proportionately so as not to reveal actual racecar settings on a public forum- but for the most part this is closely accurate info.
I just for the first time pulled the shocks on the racecar of the new team I am working on this year (NASCAR Super Truck team). This is more minor league stuff (in other words I need to keep my day job- so it is not like we have unlimited funding like the Cup and Busch cars. We are more grass roots racing although we are the premeir 1/2 oval in the country and the big boys will seek our advice when they run the Camping World series here. With that said, we stuggle with money, sponsorship, and testing funds. Racing is very expensive at this level. Alot of teams are getting by on shoestring budgets so we do things as funding will allow. In best words- We do not use all new parts every race.
I, for the first time, have collected enough data to get the spring rates, roll axis, and X-weight where it is functioning about perfect. That was last race. Since I have pulled the shocks to send them out for dyno to see what and where the shock are I have been working with- The previous owner of this race trcuk did not have anything labeled and was valving them himself- So I had no clue what the as "suppose to be" nor did a have a scienticic answer to where they really are (ie- being worn out or not) other than the non-scientific way of simply pushing and pulling them with my hands.
Lets just say I know from previous stuff I want to be somehwere (remember I am not giving specifics) in the vacintity of 5-12 (5 compression/ 12 rebound) on the left rear alone. It is what we refer to as a "hold down" shock because the high rear rebound will hold the chassis weight from diagonally transfering onto the RF. Under hard braking, this will help the car rotate better if the driver needs to stand on the brake p0edal a little harder going in deeper. There is a lot of other factors into play (one major one is the compression of the chassis entering the banked corner. The RF take the blunt of that conbined with braking force and will build cross weight to tighten the car merely upon entering the bank first on the gradual onset. (uneven chassis footprint of all 4 tires becuase of unlevel and ever so changing ground).
What I had back there- and I knew after the last testing and race that something major was wrong going in (go into turn 1 and turn 3 banks) was tht under hard braking the car was tighting up and the nose going for the wall- then once the binders were released he could turn...and turn well through steady state. Then it again tightened and bobbled coming off 2 and 4 (main 2 because that turn is smoother, 4 goes off camber and turns the car based on physics of the track)....
...so when I pulled shocks to check them I was not amazed to see something along the lines of a 7-4 back there on LR instead of a 5-12. The coming off was a dyno'ed 2-3 which he had valved at a 5-7 (which is correct, but worn). COming off we were standing on the inside rear (LR) and the car would tighten towards the wall under throttle. Car should be much better this race....and that's how shocks are used.
I am also just working with the rear for now- can't win a race overnight. Takes time to collect data and make the next call without wasting money we do not have in the budget. The fronts are 6-9's. They will probably be valved down to 5-7's after testing/race day since we do not have a separate test night prior to race day this next race. Its all time and money- and no one has either unless you are a verteran team with years of racing charts. Its a fun game for a guy like me coming in with knowledge but no charts. You make too many changes and wad up your driver into the wall and you won;t make next race. Always make little changes so your driver has confidence as to what will be under him- never send a car out with big changes or you'll end up in the wall and going home early every time- or - you just won;t be competitive being cautious that you might as well not even try. We go out fairly blind in qualifying and have 2 laps to get the tires hot and the job done- no time for pussyfooting.
I just for the first time pulled the shocks on the racecar of the new team I am working on this year (NASCAR Super Truck team). This is more minor league stuff (in other words I need to keep my day job- so it is not like we have unlimited funding like the Cup and Busch cars. We are more grass roots racing although we are the premeir 1/2 oval in the country and the big boys will seek our advice when they run the Camping World series here. With that said, we stuggle with money, sponsorship, and testing funds. Racing is very expensive at this level. Alot of teams are getting by on shoestring budgets so we do things as funding will allow. In best words- We do not use all new parts every race.
I, for the first time, have collected enough data to get the spring rates, roll axis, and X-weight where it is functioning about perfect. That was last race. Since I have pulled the shocks to send them out for dyno to see what and where the shock are I have been working with- The previous owner of this race trcuk did not have anything labeled and was valving them himself- So I had no clue what the as "suppose to be" nor did a have a scienticic answer to where they really are (ie- being worn out or not) other than the non-scientific way of simply pushing and pulling them with my hands.
Lets just say I know from previous stuff I want to be somehwere (remember I am not giving specifics) in the vacintity of 5-12 (5 compression/ 12 rebound) on the left rear alone. It is what we refer to as a "hold down" shock because the high rear rebound will hold the chassis weight from diagonally transfering onto the RF. Under hard braking, this will help the car rotate better if the driver needs to stand on the brake p0edal a little harder going in deeper. There is a lot of other factors into play (one major one is the compression of the chassis entering the banked corner. The RF take the blunt of that conbined with braking force and will build cross weight to tighten the car merely upon entering the bank first on the gradual onset. (uneven chassis footprint of all 4 tires becuase of unlevel and ever so changing ground).
What I had back there- and I knew after the last testing and race that something major was wrong going in (go into turn 1 and turn 3 banks) was tht under hard braking the car was tighting up and the nose going for the wall- then once the binders were released he could turn...and turn well through steady state. Then it again tightened and bobbled coming off 2 and 4 (main 2 because that turn is smoother, 4 goes off camber and turns the car based on physics of the track)....
...so when I pulled shocks to check them I was not amazed to see something along the lines of a 7-4 back there on LR instead of a 5-12. The coming off was a dyno'ed 2-3 which he had valved at a 5-7 (which is correct, but worn). COming off we were standing on the inside rear (LR) and the car would tighten towards the wall under throttle. Car should be much better this race....and that's how shocks are used.
I am also just working with the rear for now- can't win a race overnight. Takes time to collect data and make the next call without wasting money we do not have in the budget. The fronts are 6-9's. They will probably be valved down to 5-7's after testing/race day since we do not have a separate test night prior to race day this next race. Its all time and money- and no one has either unless you are a verteran team with years of racing charts. Its a fun game for a guy like me coming in with knowledge but no charts. You make too many changes and wad up your driver into the wall and you won;t make next race. Always make little changes so your driver has confidence as to what will be under him- never send a car out with big changes or you'll end up in the wall and going home early every time- or - you just won;t be competitive being cautious that you might as well not even try. We go out fairly blind in qualifying and have 2 laps to get the tires hot and the job done- no time for pussyfooting.
Last edited by SlickTrackGod; 05-21-2014 at 04:59 PM.
05-27-2014, 03:21 PM
#79
Re: Front Weight Jacks
Dean,
My friend answered below, he is basically saying that a car very rarely goes into steady state in real world situations, and so upping compression instead of getting stiffer springs works better:
I have a feeling both of you are right, but perhaps one application is maybe better suited for street and one is better suited for a race track?
My friend answered below, he is basically saying that a car very rarely goes into steady state in real world situations, and so upping compression instead of getting stiffer springs works better:
The use of shock valving is not a lateral thing, it is a dynamic thing. What does this mean? Regardless of shock valving, the car will eventually get to roll over to corner set (steady state) and then balance of the car is solely dependent on the spring rate, roll centers, and sway bars at that point.
Shock valving only plays a part in corner entry, corner exit, acceleration or deceleration (or any of the two above combined).
Pretty much all motions, cars are very rarely at a SS condition, maybe if your were on a flat course with a large contact radius. Here is where theory does not apply well to real life.
Generally to reduce nose dive "rate" of the front suspension (under braking)you would increase compression valving if you decrease spring rate- and vice versa. What is not changing is the amount of overall travel- only the time it takes to get to that ultimate travel is what changes in shock valving.
Yes
so now lets look at the rear. The two things rear compression valving affect is rear loading, and lateral loading. Rear loading is of course acceleration, and lateral loading is the weight going onto the outside wheel under cornering. If you up the compression rate of the rear shock to compensate for lateral loading, (lets say we are turning left), then the RR tire will load more in corner entrance to steady state as the car first lifts off slightly if any straight line braking happens- THEN it will start to load more as the car settles into squat corner set. As this is happening, the car can (if valved right) will compensate for a reduced spring rate ONLY WHEN the shock is settling down in compression stroke towards corner set. Once corner set is reached, the car will not lean on the RR as much and the car will push at steady state....
Lateral loading term is in correct here, Lateral load is what the tire sees at contact patch…springs only work up and down and the shock only works for up and down also. But I understand what he means and as a result I can respond. All he says is true except the last line which is valid since we are not looking at the entire car and balance. AT this ultimate compression of SS, it will not push more or less then before since we have no increased stiff ness only controlled the rate, he has in fact contacticted himself. Since a car is dynamic then a stiffer compression rate of damping will increase axle stiffness which could cause it to oversteer rather then understeer in corner entry.
...Now, as you get back onto the throttle coming off, the weight transfer of the chassis now again stands on the rears ( the RR already loaded) and the weight will rotate off the front onto the LR tire and further tighten the hell out of an already tight /push car at steady state.
Coming off SS to onto the throttle is not SS so this is all garbage.
Now let’s look at what controls body roll+ not compression. The rebound is what controls body roll. Spring rate controls body roll angle, and compression spring rate controls mainly the wheel movement upward "abruptly" when the wheel hits a bump. In other words, Compression is a false stability that only lasts for the moment, whereas spring rate is a stable platform to lean on.
This is ok statement
Compression should always be valved low. This allows for wheel movement to follow (or contour) to the road surface to maintain mechanical grip. There is always a combined motion ratio of the weight of the car that needs to be addressed through a combination of spring rate + compression valving- so thus the one is in sequence with the other as one does the other increases (and vice a versa) Spring rate changes have to do with roll center heights.
This is such a ultimate singular thinking that it’s clear he never actually goes to the track. Dyanmics of a car will be controlled with better damping, so once we have this ideal setting he is talking about we can then alter this setting and tune a variety of characteristics from the car with a change in compression valuing and come rebound.
Get a roll center height too low up front? and the need for heavy spring to control lateral load will cause reduced mechanical straight line braking rip over an imperfect road surface.
True, more weight transfer better braking. But a roll center and sprint rate are not linked so I am not sure why this is the answer to a question.
Get a roll center too high up front? and the soft springs will not hold up the chassis under extreme braking conditions and thus result in alot of brake dive and suspension travel (as well as a lot of RC migration- which changes the angle of the overall roll axis front to rear in lateral proportion.
same as above.
Shock valving is basically the driver's need going into and coming out of corners under hard braking and hard accelerations...period.
Lets build a better sentence here that is less ultimate.
“ most normally The control of a car in dynamic motion of supported by a force through a aligned spring, is done with a damper. These dampers have valuing sometimes is adjustable, sometimes it is no like a leaf spring”
Rebound is what controls roll, not compression. It is a much better tool to use to control roll rate, and use springs to control overall roll angle.
False
Softer suspensions give more grip. Harder suspensions give more grip.
Mass, Spring rate and Shock rates are all equally important in all motions.
.
Shock valving only plays a part in corner entry, corner exit, acceleration or deceleration (or any of the two above combined).
Pretty much all motions, cars are very rarely at a SS condition, maybe if your were on a flat course with a large contact radius. Here is where theory does not apply well to real life.
Generally to reduce nose dive "rate" of the front suspension (under braking)you would increase compression valving if you decrease spring rate- and vice versa. What is not changing is the amount of overall travel- only the time it takes to get to that ultimate travel is what changes in shock valving.
Yes
so now lets look at the rear. The two things rear compression valving affect is rear loading, and lateral loading. Rear loading is of course acceleration, and lateral loading is the weight going onto the outside wheel under cornering. If you up the compression rate of the rear shock to compensate for lateral loading, (lets say we are turning left), then the RR tire will load more in corner entrance to steady state as the car first lifts off slightly if any straight line braking happens- THEN it will start to load more as the car settles into squat corner set. As this is happening, the car can (if valved right) will compensate for a reduced spring rate ONLY WHEN the shock is settling down in compression stroke towards corner set. Once corner set is reached, the car will not lean on the RR as much and the car will push at steady state....
Lateral loading term is in correct here, Lateral load is what the tire sees at contact patch…springs only work up and down and the shock only works for up and down also. But I understand what he means and as a result I can respond. All he says is true except the last line which is valid since we are not looking at the entire car and balance. AT this ultimate compression of SS, it will not push more or less then before since we have no increased stiff ness only controlled the rate, he has in fact contacticted himself. Since a car is dynamic then a stiffer compression rate of damping will increase axle stiffness which could cause it to oversteer rather then understeer in corner entry.
...Now, as you get back onto the throttle coming off, the weight transfer of the chassis now again stands on the rears ( the RR already loaded) and the weight will rotate off the front onto the LR tire and further tighten the hell out of an already tight /push car at steady state.
Coming off SS to onto the throttle is not SS so this is all garbage.
Now let’s look at what controls body roll+ not compression. The rebound is what controls body roll. Spring rate controls body roll angle, and compression spring rate controls mainly the wheel movement upward "abruptly" when the wheel hits a bump. In other words, Compression is a false stability that only lasts for the moment, whereas spring rate is a stable platform to lean on.
This is ok statement
Compression should always be valved low. This allows for wheel movement to follow (or contour) to the road surface to maintain mechanical grip. There is always a combined motion ratio of the weight of the car that needs to be addressed through a combination of spring rate + compression valving- so thus the one is in sequence with the other as one does the other increases (and vice a versa) Spring rate changes have to do with roll center heights.
This is such a ultimate singular thinking that it’s clear he never actually goes to the track. Dyanmics of a car will be controlled with better damping, so once we have this ideal setting he is talking about we can then alter this setting and tune a variety of characteristics from the car with a change in compression valuing and come rebound.
Get a roll center height too low up front? and the need for heavy spring to control lateral load will cause reduced mechanical straight line braking rip over an imperfect road surface.
True, more weight transfer better braking. But a roll center and sprint rate are not linked so I am not sure why this is the answer to a question.
Get a roll center too high up front? and the soft springs will not hold up the chassis under extreme braking conditions and thus result in alot of brake dive and suspension travel (as well as a lot of RC migration- which changes the angle of the overall roll axis front to rear in lateral proportion.
same as above.
Shock valving is basically the driver's need going into and coming out of corners under hard braking and hard accelerations...period.
Lets build a better sentence here that is less ultimate.
“ most normally The control of a car in dynamic motion of supported by a force through a aligned spring, is done with a damper. These dampers have valuing sometimes is adjustable, sometimes it is no like a leaf spring”
Rebound is what controls roll, not compression. It is a much better tool to use to control roll rate, and use springs to control overall roll angle.
False
Softer suspensions give more grip. Harder suspensions give more grip.
Mass, Spring rate and Shock rates are all equally important in all motions.
.
05-27-2014, 03:53 PM
#80
Re: Front Weight Jacks
Dean,
My friend answered below, he is basically saying that a car very rarely goes into steady state in real world situations, and so upping compression instead of getting stiffer springs works better:
I have a feeling both of you are right, but perhaps one application is maybe better suited for street and one is better suited for a race track?
My friend answered below, he is basically saying that a car very rarely goes into steady state in real world situations, and so upping compression instead of getting stiffer springs works better:
I have a feeling both of you are right, but perhaps one application is maybe better suited for street and one is better suited for a race track?
The car most always goes into steady state unless the transition is quick enough to never get there in a chicane.
Hellzwingz- give him one simple question for me (this answer will probably be quite amuzing based on his already responses) Why does not a car in a large freeway overpass enter steady state? I mean one where the car is pressed into it for about 10 seconds around a sweeping ramp? That is about as basic 101 I can ask him. waiting for his response.
edit- nevermind. He clearly does not understand vehicle dynmaics. I am not going to wate my time trying to bring him up to speed why his imbalanced car will only be balanced during shock transition- the imbalanced at steady state-why I am not wasting time? he clearly stated a car is never in steady state. he's clueless. He's one of the many I label as know just enough to be his own danger because he thinks he understands- but there is far more to what he really realizes.
Dean
No for everyone else reading this looking for an answer- the car DOES reach a "steady state" angle of lean in a corner. It is a roll angle of the chassis. lets say the roll angle is 3*. If you are in steady state, the car has reached this. As the car is "set" the wheels will still independantly hit imperfections on the road surface if the road is not smooth. THe fron may go to 3 1/4* as the rear goes to 2 7/8*. THe momentary breach of 3* set may cause the tire to absorb and deform more based on its footprint/vehicle weight, and PSI. If it deforms enough then lateral mechanical grip can be mometariy diminished to cuase lateral slip and then a regain of traction when over the imperfection of road. It corner set, these imperfections are what make a chasiss balnce feel like little push/loose/push loose sequences where most people refer to a chassis as "dancing" in a corner.
To sum this up, if the chassis in the above example reaches 3* roll angle then it has reached set or steaqdy state. If it roll right into a chincane only 2* then 1 second later is yanked back left 2*, then thirdly yanked rioight and out onto a straight 2* it never reached steady state in any of the three qbrupt steering movements because the transition of the chicane did not yeild enough time for the chassis to reach set- this is very rare on a race track unless it's a little jiggle or jont on a course. Most corners will reach an apex arch that the car will sustain a "steady state set of body roll in that lateral direction of gravity until the car is steered out of that corner. If you are not? then you need driving leassons on driving a car smooth...period.
Last edited by SlickTrackGod; 05-27-2014 at 04:08 PM.
06-23-2014, 06:29 PM
#81
Re: Front Weight Jacks
And it is done....
Im hoping i can make it to the AutoX on Sunday, but it's going to be SOOO flippin hot out there Im not sure....
Im sure you're used to racing in the heat Dean, given your history... but Im not sure how happy I'm gonna be about it.
The steering definitely feels a little heavier... but I wasnt able to get it to kick out like I normally do making a certain corner/intersection on my commute... so it seems to be holding better as well. So far so good.
We extended the housing out a little so as not to lose all my positions, and also it helped it clear the sway bar mount. Gonna have to keep an eye on the welds to see if it holds but its a pretty thick plate and the welds were really well done on it so it should hold given the direction the loads are on it. I'll have to keep an eye on it, though.
Im hoping i can make it to the AutoX on Sunday, but it's going to be SOOO flippin hot out there Im not sure....
Im sure you're used to racing in the heat Dean, given your history... but Im not sure how happy I'm gonna be about it.
The steering definitely feels a little heavier... but I wasnt able to get it to kick out like I normally do making a certain corner/intersection on my commute... so it seems to be holding better as well. So far so good.
We extended the housing out a little so as not to lose all my positions, and also it helped it clear the sway bar mount. Gonna have to keep an eye on the welds to see if it holds but its a pretty thick plate and the welds were really well done on it so it should hold given the direction the loads are on it. I'll have to keep an eye on it, though.
Last edited by InfernalVortex; 06-23-2014 at 06:32 PM.
09-04-2014, 02:59 PM
#84
Re: Front Weight Jacks
Ive had one setback after another... but should be racing this weekend. On the street the rear end feels way more planted, steering is a little heavier. It's much more controllable in a low gear, corner exit situation. It normally would kick out into a controllable amount of oversteer but now it doesn't.
A little less "fun", but it definitely feels faster and more sure-footed. Im expecting the difference be pretty obvious on Sunday.
A little less "fun", but it definitely feels faster and more sure-footed. Im expecting the difference be pretty obvious on Sunday.
09-05-2014, 12:47 PM
#85
Re: Front Weight Jacks
I have had similar results. Heavier steering, much planted in the rear. Great on low gear turning and predictable corner exit (it now exits fast with grip). My only gripe was in transitioning from quick left to quick right for example, there is just so much more roll that I need to put in stiffer springs or something (still haven't got around to doing so)
09-05-2014, 04:19 PM
#86
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Car: '89 Formula
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Re: Front Weight Jacks
Infernal is second from the bottom. Hellz, what hole position are you using?
09-05-2014, 11:10 PM
#87
Re: Front Weight Jacks
I do not think I have ever been to a race track on a cold day. I though "racing" and "Hotter than hell" go hand in hand...lol
Most people that run a setup on the street find out they really need to drop it one more once the tires get hot on an autox course...but, you will be putting it right back up one notch after you try and drive home like that.
Hellz, just go up in Sway bar size. The lower RC will of course leverage harder as well as the increased grip will do so also. Going a larger spring rate can cause a jacking effect ont he rearend and cause the car to unload or highside under very hard braking /corner entry.(feeling a lot like how it did prior to the RC change and the current spring rate. A rear RC change is better quickly tuned with a larger bar (or just manipulate the spread of the sway bar mounts on the axle to adjust the bar's efffectiveness.
PS- we've been on a twoi month hiatas in our race schedule- I am so glad because we have been seeing humidity like I have never seen in So cal this summer. I just finished my new grocery getter in those weekends off. One of two in the country= a W202 C-class BRABUS. I built the living crap out of the suspension and it actually is kindof scaring m because I have developed suspension subframe flex- time to make some custom braces.
pss- Yes I have Koni Yellows on it,... and Michelin Pilots
Most people that run a setup on the street find out they really need to drop it one more once the tires get hot on an autox course...but, you will be putting it right back up one notch after you try and drive home like that.
Hellz, just go up in Sway bar size. The lower RC will of course leverage harder as well as the increased grip will do so also. Going a larger spring rate can cause a jacking effect ont he rearend and cause the car to unload or highside under very hard braking /corner entry.(feeling a lot like how it did prior to the RC change and the current spring rate. A rear RC change is better quickly tuned with a larger bar (or just manipulate the spread of the sway bar mounts on the axle to adjust the bar's efffectiveness.
PS- we've been on a twoi month hiatas in our race schedule- I am so glad because we have been seeing humidity like I have never seen in So cal this summer. I just finished my new grocery getter in those weekends off. One of two in the country= a W202 C-class BRABUS. I built the living crap out of the suspension and it actually is kindof scaring m because I have developed suspension subframe flex- time to make some custom braces.
pss- Yes I have Koni Yellows on it,... and Michelin Pilots
Last edited by SlickTrackGod; 09-05-2014 at 11:53 PM.
09-06-2014, 03:33 AM
#88
Re: Front Weight Jacks
I already have a 24mm bar... I figure if that's not big enough, I'll just wait til I cut the rear springs a little more and get some lowered ball joints for the front... should drop the car a little and stiffen up the rear at the same time. If that doesnt work - weight jacks and custom spring rates.
After riding around in it I see what Dean is talking about now with the leverage the center of mass has on the roll center... But that's clearly just the price you pay for having both tires firmly on the ground instead of just one of them.
I trusted dean that I "needed" this, and I intellectually could see what he was saying. But now after driving it before and after, I understand completely what a difference it makes because you can feel it. I should be able to floor it hard coming out corners and throw it in a lot harder too. The transitions are a concern, as I dont really get chances to play with that on the street, but I'll have to see how it feels in the slaloms on Sunday.
After riding around in it I see what Dean is talking about now with the leverage the center of mass has on the roll center... But that's clearly just the price you pay for having both tires firmly on the ground instead of just one of them.
I trusted dean that I "needed" this, and I intellectually could see what he was saying. But now after driving it before and after, I understand completely what a difference it makes because you can feel it. I should be able to floor it hard coming out corners and throw it in a lot harder too. The transitions are a concern, as I dont really get chances to play with that on the street, but I'll have to see how it feels in the slaloms on Sunday.
Last edited by InfernalVortex; 09-06-2014 at 03:36 AM.
09-06-2014, 09:03 AM
#89
Re: Front Weight Jacks
I already have a 24mm bar... I figure if that's not big enough, I'll just wait til I cut the rear springs a little more and get some lowered ball joints for the front... should drop the car a little and stiffen up the rear at the same time. If that doesnt work - weight jacks and custom spring rates.
After riding around in it I see what Dean is talking about now with the leverage the center of mass has on the roll center... But that's clearly just the price you pay for having both tires firmly on the ground instead of just one of them.
I trusted dean that I "needed" this, and I intellectually could see what he was saying. But now after driving it before and after, I understand completely what a difference it makes because you can feel it. I should be able to floor it hard coming out corners and throw it in a lot harder too. The transitions are a concern, as I dont really get chances to play with that on the street, but I'll have to see how it feels in the slaloms on Sunday.
After riding around in it I see what Dean is talking about now with the leverage the center of mass has on the roll center... But that's clearly just the price you pay for having both tires firmly on the ground instead of just one of them.
I trusted dean that I "needed" this, and I intellectually could see what he was saying. But now after driving it before and after, I understand completely what a difference it makes because you can feel it. I should be able to floor it hard coming out corners and throw it in a lot harder too. The transitions are a concern, as I dont really get chances to play with that on the street, but I'll have to see how it feels in the slaloms on Sunday.
As for the car being tight on transitions? You will need to now drive the car going in much much harder and use the brake pedal to set the attitude of the chassis. You can now throw the car into the conrer to get it to rotate. Your left foot is your best friend- remember that. I preach to everyone I mentor that you can not be fast on a race track unless you are using your brake pedal. You can see me bitching to my passenger about this very thing in the Ferrari video I posted above. I stuggle in those cars to get my left leg under the steering wheel and onto the brake pedal to trailbrake going into and through corners, especially on those tight little courses where you have to use a lot of steering angle. The Lambos are worse because even my throttle leg is AWAYS in contact with the underside of the steering wheel. It is tough when you have no room for steering wheel, hand and leg while pulling the wheel down to the right while trying to finesse a throttle pedal with over 500hp. Mr Toad's wild ride.
Good luck on Sunday.
ps- when ever I would autox the Camaro, I would fuel it up 5/8 a tank EXACTLY for two reasons. 1 was to keep the consistant fuel load but keep the weight low(remeber I has a super light weight nose so I keep rear polar weight low also- you may feel more balanced with a full fuel load), And #2- if I ran that car under a half tank of fuel it would cavitate and stall or hesitate the engine under hard cornering loads. The motor would definately die on me if I did any kind of sustained g turn with 3/8 a tank
Last edited by SlickTrackGod; 09-06-2014 at 09:19 AM.
09-06-2014, 09:27 AM
#90
Re: Front Weight Jacks
Dean my rear springs are NNL IROC springs. They may well be on the soft side but they were mid range IROC springs from the factory. Now they're cut so who knows.
I have been trying to source smaller bars locally for a while now just because shipping on sway bars is a pain. But I figure with the relocated phb it will accomplish some of what I was trying to do with by getting a smaller sway bar anyway. I will keep an eye out for wheel hopping. And for a smaller rear bar if you think it would help. One of the big reasons my car is so bad about all this is the 34/24 bars I have. Ideally I think I'd run a 36/21 or something. But I figure the phb relocation is something I was going to want to do eventually anyway and it seemed to suit the combo I already have pretty well.
I have been trying to source smaller bars locally for a while now just because shipping on sway bars is a pain. But I figure with the relocated phb it will accomplish some of what I was trying to do with by getting a smaller sway bar anyway. I will keep an eye out for wheel hopping. And for a smaller rear bar if you think it would help. One of the big reasons my car is so bad about all this is the 34/24 bars I have. Ideally I think I'd run a 36/21 or something. But I figure the phb relocation is something I was going to want to do eventually anyway and it seemed to suit the combo I already have pretty well.
Last edited by InfernalVortex; 09-06-2014 at 09:31 AM.
09-06-2014, 10:15 AM
#91
Re: Front Weight Jacks
Its good you have the 24, you'll need it with the dropped rear RC. I was just surprised you were using it without the PH drop.
I ran a 34 soild front and a massive 25mm rear bar on my V6. Remeber though I did not have the front heavy V8 roll weight nor brake dive weight. Both of these change the RC points in dynamic motion. The V8 cars brake dive where as my 6 stayed put. My weight was also back a little further. I added heavy dynamat to the entire floorboard and intot he rar seat are, yet I lightend the heavyass rear exhaust sytem and dropped 40lbs off the back polar weight wise. My weight was low and more centralized between the wheels.
Now in considering this thought, the thing I fought was the heavy rear glass- that was it. The upper weight of the car would motion forward on a left turn and the rear left of the vehicle wants to obviously throw itself over to the right front
(see diagram) The purple thick is dynamic roll axis, thin is static of course. Think of the weight teeter tottering over this axis and the weight of the car (use a pencil held art different angle of rioll axis to visualize this.
Now consider the 3d effect of the weight and how the chassis flexes. Think of the load of the right front wheel pushing up on the chasiss as it loads the RF suspension mount points (mainly the upper strut tower.) now look at the 3pt STB. The diagonal link in this direction of force (green arrow pointing at it) This combined with the windshield of the car (YES the WINDSHIELD of the car is a key point in aiding chassis rigidity and is considered in crash design ) these 3pt braces hold the windshield/firewall area from flexing towards the strut top.
I could remove just the 3rd pt parts of the STB (leaving the main cross bar) and my car would become more loose-why? the chassis would flex along the blue dotted line and the resulting kink in the chassis flex would lift the rear area of the car and thus lessen pressure on the inside rear tire. Yes this removal of a 2 little diagonal STB bars would loosen the car as much as raising the rear sway bar 2mm.
I ran a 34 soild front and a massive 25mm rear bar on my V6. Remeber though I did not have the front heavy V8 roll weight nor brake dive weight. Both of these change the RC points in dynamic motion. The V8 cars brake dive where as my 6 stayed put. My weight was also back a little further. I added heavy dynamat to the entire floorboard and intot he rar seat are, yet I lightend the heavyass rear exhaust sytem and dropped 40lbs off the back polar weight wise. My weight was low and more centralized between the wheels.
Now in considering this thought, the thing I fought was the heavy rear glass- that was it. The upper weight of the car would motion forward on a left turn and the rear left of the vehicle wants to obviously throw itself over to the right front
(see diagram) The purple thick is dynamic roll axis, thin is static of course. Think of the weight teeter tottering over this axis and the weight of the car (use a pencil held art different angle of rioll axis to visualize this.
Now consider the 3d effect of the weight and how the chassis flexes. Think of the load of the right front wheel pushing up on the chasiss as it loads the RF suspension mount points (mainly the upper strut tower.) now look at the 3pt STB. The diagonal link in this direction of force (green arrow pointing at it) This combined with the windshield of the car (YES the WINDSHIELD of the car is a key point in aiding chassis rigidity and is considered in crash design ) these 3pt braces hold the windshield/firewall area from flexing towards the strut top.
I could remove just the 3rd pt parts of the STB (leaving the main cross bar) and my car would become more loose-why? the chassis would flex along the blue dotted line and the resulting kink in the chassis flex would lift the rear area of the car and thus lessen pressure on the inside rear tire. Yes this removal of a 2 little diagonal STB bars would loosen the car as much as raising the rear sway bar 2mm.
09-06-2014, 10:24 AM
#92
Re: Front Weight Jacks
Now focus on the rear blue circle area and how it motions up, over, and then down onto the RF of the chassis over the yawed RC. The more the rear RC point migrates right (via a heavier spring on the right and a lighter spring on the left {AhHA!!! this is done more predominatly by using progressive rate springs}) we move the fulcrum point of the RC to the left under dynamic lateral load and thus the percentage of weight on the LR increases via the teeter tooter effect.
If you use a linear heavy rate spring, the spring will release with a heavier rate at free height then a progressive spring will. Taking out chassis flex, not jacking, a slightly shorter TQarm to promote squat, a lot of rear rebound (which yanks the wheel upward under heavy braking to get the car to rotate initially- AHHa!- hence the use of brake pedal and tossing the car hard into a turn) and a heavy rear bar with little front weight to dive and roll ove the nose...and you are getting the picture of the jetfighter like turn-in's my car was able to accomplish.
Also, to promote squat, BUT, not to induce wheel hop comes from working with the rear progressive springs and ride height to make sure the rate was enough of a build upon squat that the LCA angle did not create wheelhop. I could exert roll understeer dynamics but not go so far as to cause inversion too much because of quick rate increase with suspension travel. Sway bars really can not assist one side to the other in wheel hop because its a slight delayed support along the chain of events.
DISCLAIMER: I never tried this with a V8 car. I do not know if you could get it to work or not. I did not have massive power either so that was never a concern. I had a car that never had to slow as much...THUS...as a result I never hadd to speed back up as much either. I had a car that maintained it's flow on a race course and was very easy to drive. Everyone else was working harder and sweating in the cockpit going from 30-60-30mph while I was going 35-55-35.
Lastly, when I was pressed hard into a corner and hit a bump, You see the pics I posted of my very light weight front brake/suspension assembly that was 4 pounds lighter each side. I was on fairly light weight "rear" Irocs on all four corners(I did not use "fronts" up front) I had Moser 26mm axles WITH drilled flanges, lightweight circletrack RP gears, Ultra light Wilwood rear brakes, trimmed down all my unnecessary metal brackets etc, chromemooly parts, Carbon fiber driveshaft, etc...evenything was light unsprung weight. I then focused on low polar weight so I could stop the rotation of the car when I threw it into and out of corners into transitions.
Lastly- being the V6 and being light, I could start with a lower static ride height and not worry about suspension travel then the V8 cars. That lower static height and less travel enabled me to have a shorter ball joint-to-strut tower distance then anyone else which did a few things. It increased my adjustment range. It decrease my camber loss (camber curve). It dynamically and rappidly increases my positive caster, AND its shorter length reduce the rear to front weight transfer leverage under braking to reduce the rear jacking effect these car are notorious for.
While the V8's were eating up tires putting down the power and then heavier braking. My lighter slower car was pissing off all the V8's out of frustration. Yes it was slow, but I was working on that too building the 3.5l motor I never got to finish when the divorce happened. Note: that close up pic of the PH relocator is a very recent shot of my old car. You will note the rust on the bolts and stuff. She had the car for sel recently and I had someone track it down and run some info on her and it. The car is for sale but she is out of state and its been sitting collecting dust and rotting for about 5 years. I do not want the thing anymore and thought a friend of mine was going to buy it for his girlfriend (Greygoose). it has been sitting outdoors in the sun and needs paint badly, as well as the Momo seats are fading badly. Its a shame what the idiot did by taking a car she could not maintain and left it to rot. Now she can't sell it either for what she "thinks" it's worth. LMAO. I built that car not to sell, I bouilt it purposely for a bullet proof daily driver grocery getter. It was my version of everyone elses minivan. Nobody wants a frikin V6 unless its a family/chick car.
If you use a linear heavy rate spring, the spring will release with a heavier rate at free height then a progressive spring will. Taking out chassis flex, not jacking, a slightly shorter TQarm to promote squat, a lot of rear rebound (which yanks the wheel upward under heavy braking to get the car to rotate initially- AHHa!- hence the use of brake pedal and tossing the car hard into a turn) and a heavy rear bar with little front weight to dive and roll ove the nose...and you are getting the picture of the jetfighter like turn-in's my car was able to accomplish.
Also, to promote squat, BUT, not to induce wheel hop comes from working with the rear progressive springs and ride height to make sure the rate was enough of a build upon squat that the LCA angle did not create wheelhop. I could exert roll understeer dynamics but not go so far as to cause inversion too much because of quick rate increase with suspension travel. Sway bars really can not assist one side to the other in wheel hop because its a slight delayed support along the chain of events.
DISCLAIMER: I never tried this with a V8 car. I do not know if you could get it to work or not. I did not have massive power either so that was never a concern. I had a car that never had to slow as much...THUS...as a result I never hadd to speed back up as much either. I had a car that maintained it's flow on a race course and was very easy to drive. Everyone else was working harder and sweating in the cockpit going from 30-60-30mph while I was going 35-55-35.
Lastly, when I was pressed hard into a corner and hit a bump, You see the pics I posted of my very light weight front brake/suspension assembly that was 4 pounds lighter each side. I was on fairly light weight "rear" Irocs on all four corners(I did not use "fronts" up front) I had Moser 26mm axles WITH drilled flanges, lightweight circletrack RP gears, Ultra light Wilwood rear brakes, trimmed down all my unnecessary metal brackets etc, chromemooly parts, Carbon fiber driveshaft, etc...evenything was light unsprung weight. I then focused on low polar weight so I could stop the rotation of the car when I threw it into and out of corners into transitions.
Lastly- being the V6 and being light, I could start with a lower static ride height and not worry about suspension travel then the V8 cars. That lower static height and less travel enabled me to have a shorter ball joint-to-strut tower distance then anyone else which did a few things. It increased my adjustment range. It decrease my camber loss (camber curve). It dynamically and rappidly increases my positive caster, AND its shorter length reduce the rear to front weight transfer leverage under braking to reduce the rear jacking effect these car are notorious for.
While the V8's were eating up tires putting down the power and then heavier braking. My lighter slower car was pissing off all the V8's out of frustration. Yes it was slow, but I was working on that too building the 3.5l motor I never got to finish when the divorce happened. Note: that close up pic of the PH relocator is a very recent shot of my old car. You will note the rust on the bolts and stuff. She had the car for sel recently and I had someone track it down and run some info on her and it. The car is for sale but she is out of state and its been sitting collecting dust and rotting for about 5 years. I do not want the thing anymore and thought a friend of mine was going to buy it for his girlfriend (Greygoose). it has been sitting outdoors in the sun and needs paint badly, as well as the Momo seats are fading badly. Its a shame what the idiot did by taking a car she could not maintain and left it to rot. Now she can't sell it either for what she "thinks" it's worth. LMAO. I built that car not to sell, I bouilt it purposely for a bullet proof daily driver grocery getter. It was my version of everyone elses minivan. Nobody wants a frikin V6 unless its a family/chick car.
Last edited by SlickTrackGod; 09-06-2014 at 11:01 AM.
09-06-2014, 05:15 PM
#93
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Car: '89 Formula
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Re: Front Weight Jacks
Dean,
Totally agree concerning the windshield and 3pt STB (fits better w/LS2!), and your tunnel brace, too. I really miss the Kenny Brown stuff. He was right on.
I have a Mark Williams 12 bolt on order (30 spline TrueTrac, set-20 bearings). I paid a little extra to make sure nothing Moser is on my car
.
Should I have them delete the pass side spring pocket since I'm running coil-overs? Imbalanced without it (especially w/Jegster)?, OR if someone should total me, resale might be better with it on? I could always have them throw the bracket in the crate.
I've got the 36/24 bar combo with #850/#200. I'm hoping that's a good starting point for the bigger rear. Putting Wilwood D-154 dual floating kit w/PB on it. I may swap later on to D-52 (not a whole lot performance dif, but a larger pad). I wanted to keep a floating caliper on the back.
Totally agree concerning the windshield and 3pt STB (fits better w/LS2!), and your tunnel brace, too. I really miss the Kenny Brown stuff. He was right on.
I have a Mark Williams 12 bolt on order (30 spline TrueTrac, set-20 bearings). I paid a little extra to make sure nothing Moser is on my car
. Should I have them delete the pass side spring pocket since I'm running coil-overs? Imbalanced without it (especially w/Jegster)?, OR if someone should total me, resale might be better with it on? I could always have them throw the bracket in the crate.
I've got the 36/24 bar combo with #850/#200. I'm hoping that's a good starting point for the bigger rear. Putting Wilwood D-154 dual floating kit w/PB on it. I may swap later on to D-52 (not a whole lot performance dif, but a larger pad). I wanted to keep a floating caliper on the back.
09-07-2014, 04:23 PM
#94
Re: Front Weight Jacks
Wow that made a HUGE difference at the autocross. The car is so much more stable and controllable. It was controllable before but it just spent oto much time trying to go sideways instead of forwards. I'd always have to let off way too much to get the rear end settled. I was really hammering on it today, and I could make the rear end dance around a little, but the car is SO much better balanced.
We usually get 8 runs, and my last 4 after the lunch break are always considerably faster.... but it poured down rain on us and the track was extremely wet from there on, so that didnt really amount to much.
I've got to learn how to drive the car better... I can tell Im leaving a lot on the table, but the car is easier to control so it'll work out.
The course was awful for a larger car... we had a couple of really, really tight 60 degree turns and an awful chicane that's just brutal on cars this size compared to some of the hatchbacks and miatas and fiat abarths and whatnot. So Im not sure the times are super relevant today, but I placed 5th out of 16 novices today.... which is my highest yet... on a course that didnt suit the car at all.
So that's my preliminary judgment on the PHBRB. Thanks Dean, it made a huge difference. I'm almost unsure if extended ball joints and stiffer springs are even a good idea at this point until i learn how to drive it a little better and get a better feel for the car. They were next on the list, but I feel like i should leave it alone a while now since I'm not fighting it anymore.
We usually get 8 runs, and my last 4 after the lunch break are always considerably faster.... but it poured down rain on us and the track was extremely wet from there on, so that didnt really amount to much.
I've got to learn how to drive the car better... I can tell Im leaving a lot on the table, but the car is easier to control so it'll work out.
The course was awful for a larger car... we had a couple of really, really tight 60 degree turns and an awful chicane that's just brutal on cars this size compared to some of the hatchbacks and miatas and fiat abarths and whatnot. So Im not sure the times are super relevant today, but I placed 5th out of 16 novices today.... which is my highest yet... on a course that didnt suit the car at all.
So that's my preliminary judgment on the PHBRB. Thanks Dean, it made a huge difference. I'm almost unsure if extended ball joints and stiffer springs are even a good idea at this point until i learn how to drive it a little better and get a better feel for the car. They were next on the list, but I feel like i should leave it alone a while now since I'm not fighting it anymore.
09-07-2014, 05:59 PM
#95
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Car: '89 Formula
Engine: LS2
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Axle/Gears: MW 3.42 12 Bolt
Re: Front Weight Jacks
Good to hear your pleased with the Jegster - the low hanging fruit (pun).
Keep going with the front, though. The car can only steer as good as the front. Ext Ball joints (raise RC) and front weight jacks (lower CG) will help you even more. The expense is not great, but a little bit of labor. That would make for a good winter project.
Congratulations on your improvements!
Keep going with the front, though. The car can only steer as good as the front. Ext Ball joints (raise RC) and front weight jacks (lower CG) will help you even more. The expense is not great, but a little bit of labor. That would make for a good winter project.
Congratulations on your improvements!
09-08-2014, 12:31 PM
#96
Re: Front Weight Jacks
Infernal: That's awesome. I know what you mean man.. The rear just feels much more stable and easier to steer into and out of a turn.
TEDS: Agree with the ext. ball joints. I have them and it improved front end stiffness and reduced some roll from the heavy front end.
Also, to answer your earlier question, I am in the bottom holes on the axle side, as well as on the body (I have UE's relocator brackets, which weld on to both sides.). Since I plan on lowering the rear about an inch to match the fronts that are lowered from the extended ball joints (wanted to get rear Voghland springs.. lower, stiffer, and lighter than stock IROCs that I have now... I have 34mm/24mm stock sway bars though..), I'll have to drill a new hole on the body side once it's lowered so that the PHB mounting point is slightly higher on the body side compared to the axle side. Here are pics of the relocation back in 2012:
TEDS: Agree with the ext. ball joints. I have them and it improved front end stiffness and reduced some roll from the heavy front end.
Also, to answer your earlier question, I am in the bottom holes on the axle side, as well as on the body (I have UE's relocator brackets, which weld on to both sides.). Since I plan on lowering the rear about an inch to match the fronts that are lowered from the extended ball joints (wanted to get rear Voghland springs.. lower, stiffer, and lighter than stock IROCs that I have now... I have 34mm/24mm stock sway bars though..), I'll have to drill a new hole on the body side once it's lowered so that the PHB mounting point is slightly higher on the body side compared to the axle side. Here are pics of the relocation back in 2012:
09-08-2014, 02:39 PM
#97
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Car: '89 Formula
Engine: LS2
Transmission: 4L65E
Axle/Gears: MW 3.42 12 Bolt
Re: Front Weight Jacks
Thanks Hellz,
I see what Infernal did to be able to use the lower bolt holes. I don't think I'll go that low, so I'll weld the support at the lowest hole. That will still give me 2 good and possibly a 3rd adjustment hole to use. Thanks
I see what Infernal did to be able to use the lower bolt holes. I don't think I'll go that low, so I'll weld the support at the lowest hole. That will still give me 2 good and possibly a 3rd adjustment hole to use. Thanks
09-08-2014, 08:10 PM
#98
Re: Front Weight Jacks
I was looking at that bracket and I just didnt like it at all as far as that was concerned. Even welded over the lowest hole it seemed like you wouldnt be able to get to the hole directly above it. You've got to be able to fit a nut or a bolt head AND a wrench on it. In fact, as far as I could tell, there was no place to put the reinforcing bar that wouldnt cover up at least two holes. That's why mine is done the way it is... I just thought it was crappy the way it was done out of the box. Hence the extra plate. Hopefully it holds up.
Last edited by InfernalVortex; 09-08-2014 at 09:16 PM.
09-09-2014, 09:13 AM
#99
Re: Front Weight Jacks
I would have liked to have had adjustability to be honest, but I'll just deal with it in the lowest hole and work from there.
Dean: Wouldn't adding a stiffer sway bar reduce stability over bumps? Would combining lowering 1", stiffer springs, and a 25mm sway bar be overkill for the street? (I have my battery relocated to the rear so there's more weight back there).
Dean: Wouldn't adding a stiffer sway bar reduce stability over bumps? Would combining lowering 1", stiffer springs, and a 25mm sway bar be overkill for the street? (I have my battery relocated to the rear so there's more weight back there).
09-09-2014, 06:01 PM
#100
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Car: 2004 Mazda RX-8
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Re: Front Weight Jacks
I would have liked to have had adjustability to be honest, but I'll just deal with it in the lowest hole and work from there.
Dean: Wouldn't adding a stiffer sway bar reduce stability over bumps? Would combining lowering 1", stiffer springs, and a 25mm sway bar be overkill for the street? (I have my battery relocated to the rear so there's more weight back there).
Dean: Wouldn't adding a stiffer sway bar reduce stability over bumps? Would combining lowering 1", stiffer springs, and a 25mm sway bar be overkill for the street? (I have my battery relocated to the rear so there's more weight back there).
http://www.stranoparts.com/partdetai...ID=0&ModelID=9
It makes it easier to adjust at the track, as opposed to lugging around 4 sway bars.