engongam

Hello all,

I have a project going on and I am having some trouble about my shocks ans springs...

Here is my thread https://www.thirdgen.org/forums/engi...305-502-a.html

and here is a video of my car (6 point roll bar installed after the video)
http://videos.streetfire.net/video/T...Jet_691494.htm

Now let's get back to business,
My main problem is when I slam on the brakes rear wheels lock and cause a wheel hop (very very very annoying and dangerous, I can not even brake a little rough...) My guess is the shocks are gone bad... Currently I am running with tokiko illumina single 5 way adjustable shocks. I do not know what bump and rebound damping concepts mean... Can you tell me more about those issuies so that I can decide whether to buy a double or single adjustable shocks...

I looked over these shocks:
1)
http://www.cachassisworks.com/iwwidb...ti_item_submit

2) http://www.summitracing.com/search/y.../?autoview=SKU

and 3)
http://www.summitracing.com/search/y.../?autoview=SKU

I am using the car on time trials, please any suggestion is important, I do not knot what to do...

Shortly I need some shocks that are capable of holding the car on road while cornering hard...

Spirngs are the second thing to think about right now, I need to conclude this shock issue first

Thanks for your time, Please do not read and go, I am open to suggestions...

BMR Sales

Your best bet is going to be the koni's. They are expensive but well worth the money.

Guest

Hi (your name?),

I finally had a chance to look over that build post and some of the pictures on it to try and gather info on what you have.

It appears you are on stock springs. I can not get the video's to play so I can not see the car in action live, but I can see in pictures that the car is rolling over hard on the outside front wheel from the massive engine weight.

Question 1- What torque arm sewtup are you running? I can see it is aftermarket but can not tell the mount location or the length. I think it may be Spohn's unit with x-member mount? I do not think it is a shorter Global West unit is it, or maybe BMR. Length is important as opposed to stock, shorter the TQarm, the more prone to wheelhop under braking.

question 2- When the wheel hop occurs, is it occuring straight line braking, or is it only in lateral braking durring corner entrance?

My guess right now is that the car is just rolling over and lighting the inside rear tire causing brake skiping or hopping on the inside rear tire. You are going to have to upp the front spring rate dramatically, BUT we are going to have to work on still getting the car to turn-in WITHOUT causing it to loosen too much when corner exit is a nightmare. An iron bigblock on a roadcourse is going to be a chalange to tame into a cornering machine. Front roll weight and nose dive are you major hurdles.

Trust me- as for shocks? Spend the money right now on Varistuts that are double adjustable, YOU WILL NEED THEM! you are going to need the advanced valving as well as separate rebound and compression adjustments.
You are going to need adjustments in the rear as well, you are also going to need panhard adjustment on both sides I think* (I say BOTH chassis and axle sides based on what I see the aprox ride height is in the pictures you have posted). If the car is lowered alot, you really do not need the chassis side adjuster as much, just the axle side. Get the one from Jegs, its a great unit.

I am taking this on as a personal challange to help you get this thing track friendly. lets keep this going here BUT for quick response if I am not paying attention then Email me also if you need to at sakeed123@aol.com (This is only for him, others please contact me through this message board, I do not wnat to be bothered with lots of emails daily from everyone- thank you kindly)

Dean

I am just starting with basic questions and info. Lets keep this simple- it will build into the technical stuff as we go, so lts try and keep the communication easy to understand. (its so much easiler if I were at the track with you for testing multiple days over a month).

Flip 2

iTrader: (1)

Rebound:
If the rebound on your rear shocks is set low, when you brake, all the weight will transfer to the front QUICKLY.
Try increasing the rebound on your rear shocks.

ALSO: Do you have lower control arm relocation brackets?
If you have lowered your car, you ABSOLUTELY need them for any kind of performance from your suspension.

Good sway bars help too.

Vetruck will be a BIG help/ enjoy!

Guest

Not to step on toes but, its the reason I want to go slow with this. I will explain why your thoughts can and probably are wrong in suggesting.

1-Rear shock rebound suggention- If he dials it up more to eliminate more front weight transfer he is skipping the rear tires MORE by unloading them.

2-Rear LCA angle. Dropping the rear LCA angle which may help reduce wheel hop under acceleration DOES THE OPPOSITE effect under braking- again, he mgith not want that yet-or- already has too much of it. I will address these sttings later after we get the car to a good baseline spring rates that will balance him in steady state of a corner. I have to get alot of info from him to see what we have to work with. Lets start with my first questions above still. I may just do thisoffline in private emails if it getss too clucttered wih posts on here.

Flip 2

iTrader: (1)

I'm not trying to second guess, much less fine tune.
I do think;
1) regardless of his current complaint, he should have the Lower Control Arm Relocation Brackets
2) he should have some handle on rebound, and what it does
3) regardless of his current of his current complaint, he wants some beefy swaybars for what he is doing

Engonogam- a third gen should be quite a sight over there... good luck!

Guest

Ok,1st, this thread will get cluttered wit way too much text to sort through and jumping into explaining things that should come later- we are out of order on sequence. I said already I would get to this stuff later. If he wants my help I will do it privately. This would have been a good learning tool for many to see what actually goes into troubleshooting a chassis. I can't be typing novels like this every other post explaining why noy to do this or that AND then type my own novel as too what to actually do next and then get the next questions answered...too much clutter coming, I can see it.

Flip2-
1: WHy should he have LCARB's right now and where should they be set? WHat are the reprocussions of them going into a corner, and coming off a corner..please explain. Also tell me what angle his control arms are right now and that you KNOW in fact he needs this right now this very instant.

2:Yes, he will have some knowledge on rebound....in due time. Rebound will help in chassis control. Chassis motion is all determined by spring rates and weights, rebound controls thoise weights... please tell me right now what those weights are? You do not know yet..... again, I will get to rebound and its uses in due time when I get to that point. I am far from it. Rebound has everything to do with spring rate and compression damper rate. it is a factor on trun-in, as well as corner exit. but we need to first work on steady state as its non hinderance to promote loss of traction though wheel skipping being set too high for his current roll angle.

3:WHY.... Why Why Why?
the bigger the sway bar the better the car corners?
Are you kidding me? Lets just lock up the whole suspension so we loose independant wheel function and mechanical grip just so the car doesn't sway. Anybody want to go drifting and just burn up tires?

If you give advice, be prepared to take criticizm. I give factual advise and I give factual critisizm to those I feel giving wrong advice. I also take critisizm and am always ready for proper debate.

I asked politely not to trash up this post, now we both have. Bet there where many interested to see this happen here without all the clutter. I have tried this a few times over the years on here ands always there is some sort of ego's that get into the way of facts. I see this day in and day at at the track pits also. All the crew wants to be the cheif and its most costly when a renegade crew member thinks he knows enough to be dangerous and make secret changes without telling anyone- Then I check it after the run and they get fired- like I wasn't going to see it. i reset it to where it should be and send them out in front of the renegade crew member first then I fire them. I do not mind asking, I ENCOURAGE IT- its how we learn. Just do not naively just start throwing out suggestions we other peoples money is on the line.

Thank you, Dean

Guest

Firther more on #3: the swaybars-

Swaybars are simply a fine tuning devise for spring rate changes. A bigger bar is just a tool for a broader range to adjust its tension up and down along the levers with race changes such as fuel load decrease and tire wear. Its is a fine tunning devise for track temp changes.

Everyone askes...What springs should I buy?

Then, I never see anyone ask What swaybar sizes should I buy. Everybody just puts on the biggest generally but why? (this is going to take a massive novel)
Lets start with what most people do on a street car in upgrades- and this will explain logic of car suspension mentality.

Whats the easiest thing to change on the car's suspension? the sway bars. A street car is heavier in roll weight- is just about every case, as bigger than stock swaybar "set" will make a car "transition" faster because it adds lateral spring rate reducing roll. It also reduces roll angle of the car with stock spring rates by adding lateral spring rate(note that it does NOT add longitudinal spring rate- theres the golden link! pun intended). So now, a car that roll left 4 degrees and then rolled right 4 degrees lifting the inside wheel geometry and subsequenty rolling onto and compression the outside suspension geometry past boundries of tire contact grip causing mechanical grip loss is now lowered because it helps contain the high body roll weight of a stock vehicle on cushy stock spring rates for the average Joe or Jane.The car only rolls 3* left and 3 * right........
.......But still thrusts upward to the sky under throttle and nose dives under hard braking. Thats why alot of your street cars corner great at high speed sweepers, but wil not rotate going into a hard slow corner and come out with the *** end all over the place as a result of snap oversteer.

So now what- as the months or years progress and the money comes in we add more and more goodies to our cars. We now get into spring rates. We buy a generic kit that is marketed like eibach pro kit because it is a package that a retailer tested with proportioned "upped" spring rates for that performance driver. The rates are upped proportionately front and rear to maintain a somewhat blance of a already somewhat balanced stock car (note I say somewhat- all Camaro's and all Firebirds that came from the factory are not all created equal in chassis weights and options. Its just a one size fits all decent rate increase- most cars will still push. which is what the factory builds into a cars initial design so that the customer does not have a panic stop and *** end arounds his or her car loosing total control- they want you to impact straight forward if possible to take a accident hit sitting straight in your seatbelt- not a side hit... So the aftermarket does not want to get sued either. If thats the only change you make, it will still be tight, not loose in cornering. They know everybody puts the bigeest sway bar they can find(in our case its the fatory 36mm/24mm combo) so when that is combined with this rate it will be "for the most part" a decent handling car. You can't go wrong buying a packaged spring rate set to start with, but each car as it progresses will need individual changes to be even close to optimum. What is optimum for one driver, is NOT for naothr driver (Always remember this point- it boils down to brake pedal skill, you can not drive fast unless you can drive with your brake- thats a whole different novel).

Then we go into that spring package is also usually sold as a "lower your car" set of performance springs. That changes the roll axis because the nose of a thrid gen goes down faster rate than the rear in roll cener ehights when lowering equal distance. Then spring package as said above will take this into account and up the front spring rate slightly more keeping the higher leveraged roll center front in place more in sequence or or in other word closer to level and not drastically cantering towards the front. (Note this is not body rake, this is the roll axis rake the boddy pivots on sideways when it rolls. It a hard imaginary thing to grasp for most people. best explained in people with hand gestures or models to simulate) The roll couple anlges forward more and lateral roll now wants to cant over the nose laterally in body roll lifing the inside rear tire. higher spring rate front to rear resists this.

Back to swaybars (I have not forgot about them) The car now with heavier springs, heavier swaybars, and lowered now only roll 2 * left and 2 * right in transition.
Yoiu have limited body roll. The car handle great right? So what is wrong? hmmmmm?
...Go though a bumpy corner, roads are not perfect, hecck racetracks aren't much better. You now are sittinghard intoa smooth corner at 45mph when the left front tire goes over a slight 1" bump in the pavement. you are already sitting on edge at 2* (because your swaybars have locked you up to only that) and the car rises on the left to go over it. On the bump and just after it the car rises to 3* so the back tire lifts when the front is on it, and sussequently the font tire lifts as the back tire goes over it and the car slides out sideways in a spin (or less it looses traction momentarily and you dirt out the corner a bit loosing time.) ......Better to have done the body roll with higher spring rates and softer bars than with softer spring rates and higher bars because each tire will act "more" independant with lighter swaybars. That same senerio where a car would roll 2* with stiffer springs and smaller swaybars would allow that one tire to momentarily compress a little more without the combined rate of the other side of the car linked through a heavy swaybar pulling the inside off the ground. You need to think of the swaybar pulling the inside off, where as the spring will push it back- this gets technical and arguements can arrise, but for the most part I am right saying what I said. Best way I can put it is a swaybar combines both left and right front suspensions even when the left is the only one that hits the bump, whereas the springs all work that corner independantly of the other side when no sway bar is present.

So why not use any sway bar at all, just use springs only? Swaybars help keep the body flat during transitions and keep the chassis from rolling over onto one corner of the car dramatically. You do not really have front to rear sway bars due to wheel base. This is hard to explain in words but basically the car needs them going into a corner on the front under braking AND cornering becuase it would just be too much force and recoil on one individual spring. The swaybar smooths the force in and smooths it back out on recoil as the chassis motion goes from all forward-to- forward & left -to- all left. And then it is released in reverse off the corner. Reason why rear swaybars are smaller or often non existant is because the directon of travel as well as grip and motion going in is much greater under braking than it is under motion and grip coming off because of vehcle dynamic, weight bias and power to the wheels.

Personally, I like cars setup with high rate front springs and medium swaybar, and lower rate rear springs with heavy swaybar. It suits my driving style. I have a heck of alot more going into the chassis setup when I do this like roll understeer, progressive rear springs (which most people hate) combined with proper shock valving (very critical) and a very flat roll couple. the car has to be close to 50/50 weight with the big bar on the rear. The heavier nosed the car is in bias the smaller the rear bar needs to be for the most part. I have not experimented with a heavy nosed car like Engongam's so this will be interesting to see if what I theory will work if he want's to participate. It has to do with roll couple- That is why I asked him to get rear roll center adjustment provisions (Jegs panhard adjuster) I wanted him to cheaply (low cost) give me some experimental imput as to how the car is reacting before we proceed further. I want to see if I can dynamically transfer some of his heavy front weight onto the rear tires but still get the inside front weigthed enough to turn-in into the corners. I have to keep him with heavy rate springs up front though to keep the car from nose diving, but get his front roll center up and his rear down without tightening him too much hurting turn-in. We are going to need good shock valving to play like this and get it to work.

Flip2- I hope you are getting a small view of the much larger picture to come. Suspensions are not an easy bolt this on and bolt that on thing to do- its a marraige of componants and proper adjustment provisions. I need to see what he has fist before we juust start telling him generic things you see here everyday on TGO programed responses.

Were my spring rates over the counter? no They were altered three different times getting the spring rates I wanted to work with and the feel I wanted in steady state roll. It take months if not years to get a car "perfect" my Camaro was what i thought 'perfect" for the caliber of parts I put into it and the chassis roll weight I had to deal with. I loved that car, even though HP wise it was my slowest car by far- but most fun to drive.Its only put down 135rwhp- yes a 2.8 V6, but it was a great canvas for cornering and braking. I never had to really slow down going into a corner so I consequently never had to speed back up as much as others......things that make you go hmmmm

Dean

engongam

Sorry about the late info, I did not have internet accsess as I am moving to a new house... Right now I'm OK

As for the first question,

I am using the stock length Spohn's Adjustable Torque Arm with TKO's crossmember...

2)
Wheel hop occurs when I cause slightly more power on the pedal than regular pushing power...
It is not about being in the corner or on a straight line, It always occurs if I do powerful stops...

As for characteristics of the car, It moves its nose very fast but after the nose come in, rear losses its grip and starts to oversteer... (I installes the 6 point cage but I welded 2 points on the rear struts, It increased the rear stability a lot...)

I'm Berk by the way

Thanks for the deep info again...

engongam

Let me give some info about the car,

It has 36mm front sway bar 24mm rear sway bar (as you said which came from factory...) and Moog Front Springs with 706# @ load height and Moog Rear Spring but I do not know its rate...

I have Spohn chrome moly welded sub frames, I have spohn LCA (non adjustable), I have Spohn Panhard bar (non adjustable), I have tokiko Illumina Shocks with 5 way adjustable (it only adjusts the stiffness) and all the bushings I have are Poly...

Roostmeyer

iTrader: (3)

Berk,

I would suggest running the Koni's, somebody correct me if I'm wrong, but I've never heard of anyone running varistruts besides drag racers. You could always ask for shock dyno plots and if they don't have them avoid that brand at all costs... Compression adjustment is nice, but at some point its just more rope to hang yourself with if your just starting to tune the car. The tokico shock dyno plots I've seen all show a ton of high speed damping, the koni's should be a lot less harsh and give you more low speed rebound damping. The compression damping will be in the ballpark and should be good enough to get you started and then some. You can always get the shocks revalved and setup for double adjustable later for enough money.

We need a little more information, what brake pads are you running with the wilwood setup? What are the brake rotor diameters? Do you have an adjustable proportioning valve or are you running the stock valve? Are you planning on tracking the car with the Kumho SPT's? As temporary fix I'd suggest dialing out some rear brake bias with a proportioning valve as a crutch to "fix" the brake hop issue. Finally whats your budget for redoing the shocks and springs? I'd keep the current sway bars as you need all the roll stiffness you can get right now with stock springs.

Moving on to other issues I see is f-bodys are already front heavy, the BBC and t56 has only added to this. I would highly suggest running the same tires/wheels all the way around the car, this will allow you to rotate the tires and get more life out of them. Running larger rear tires is only going to make the car want to push more. An 18" wheel should let you go just as big in the front as in the rear at the expense of turning radius.

Also do some calcs on the bending stresses on your studs from running a 120mm vs 120.6mm bolt pattern, you may want to increase the backspacing on your wheels and run a 1/2" spacer if your stuck with 120mm wheels on that side of the world.

Guest

Vaistruts are hand made and individually dyno'ed with each build. They arre digressive valve, can be custom valved and fully rebuildable. they are CNC machined bodies out of aluminum with hardened 5/8" Rods.

Koni yellows as good as they are for an over-the-counter strut do not hold a candle to Varistruts.

Here is a quote off Varistruts site for further details:

Fluid Control

A shocks purpose is to limit the rate at which the suspension moves, whether
induced by road irregularities or by chassis movement. By carefully controlling
the rate of fluid flow into the different areas of the shock we can better
manage the suspension’s ability to keep the tire in contact with the road.
VariShocks operate with zero bleed, meaning that absolutely all fluid flow
is purposely directed and metered. By contrast, many manufacturers skimp
on sealing the shock’s internals to lower manufacturing costs. The allowed
internal leakage makes valving adjustments less effective and lacking in
precision. The VariShock total-seal design gives you improved control over the
entire range of damping and enhances adjustment effectiveness at the slower
range of piston speeds (0-4 in/sec) that control large chassis movements and
vehicle handling.

4

A combination of fatigue-resistant deflective-disk and adjustable poppet valves focus damping forces at a
range useful to the widest variety of vehicle types and performance applications. Damping-force ranges differ
depending upon the adjustment features and mounting configuration of the shock. Custom valve sets are
also available to alter the adjustment range of compression or rebound independently. VariShocks provide
digressive damping to permit finer adjustment at the higher range of piston speeds (6-12 in/sec) that control
rapid suspension movement and ride harshness. To give better control of vehicle-handling without rapidly

increasing ride harshness, rebound (extension) valving is purposely stiffer with a broader adjustment range.

engongam

12.2 inch Slotted Zinc Plated Rotors at front, 12 inch slotted and drilled rotors with racing compound pads... I have an adjustable prop. valve, I removed the rubber thing from old valve, but even it does not work, the old valve is still there... (I kept it bacause it distributes and collects the brake lines).

I just came from the track and I dialed out the rear brakes bias but it did not completely erased the problem, It reduced though... I need to do a harder brake to cause a wheel hop...

Guest

Just to post an update on this, Berk and i have been converseing privately exchanging information and imput. As expected after a little track testing he has confirmed to me the problems solely first base on spring rates. Without the proper spring rates and roll centers, there is nothing more we can do.

We are all on a budget in life (I know I am) so we are right now trying to fiugure what is the best route for Berk to take as for what is needed on the fornt of his car chassis height and geometry wise so I know more what he is willing to do and what i have to wort with.

The nose of this car as all can imagine is very heavy- but is fully doable with the correct geomerty and parts for adjustment.

I have asked him to hold off on shock purchases in foavor of needing other critical things first since the tokico Illuminas are at the very least a decent shock- not upper end, but not lower end either. they will do for now. In other words, he has much weaker links to focus his money on right now like

1)Spring rates I have recommended to him starting at 1100lb fronts, 225lb rears. he wants pretty much an all out track car that does not value creature comfort for everyday driving- PERFECT! I love it. He wants to use that BBC to its fullest potential.

2) getting the chassis rake and ride heights to a geometrical favorable ride eheight for suspension articulation on the front. This will be actually his fiorst decission and will affect what 1100lb spring height he purchase. Whether he can and wants to buy Racecraft drop spindles to keep the articulation angles of the front Aarms from inverting and loosing camber in arch, or if money is more tight and we just go to extended ball joints, or none at all and keep the chassis ride height even higher. These decissions will affect what fornt roll center heights we have to work with and what leverage we have on the springs Via CG height in proportion to the RC height. I may change spring rate down to 1000 lbs if he can get the racecraft spindles. i can get the car and overall CG lower with the front RC hugher and still have a good camber curve with the Racecraft spindles.

3) Installing, reinstalling, and probably again reinstalling springs until they are trimmed tot he desired ride height and the car is sacling 50/50 cross weights- hopefully he can get access to scales and is willing to do MAJOR trial and error till this is optimum! IT TAKES ALOT OF WORK.

4) once the front is set to good A-arm angle for arch gain of up to 2" of travel most, 1" travel least in geomerty centerline, that will determine front ride height and then set the rear proportionately. Rear weight jacks would be nice, but I do NOT like GC weigh jack kits with those tiny springs. The reason is you loose too much free coils. The rates change too drastically in travel- A 225lb 10" tall spring compressed one inch is not the same rate as a 225lb 6" tall spring comprssed at one inch when you compress both to 2 inches and re valvuue their rates. The shorter one generally has fewer free coils and will increase its rate at a faster rate when depressed than the taller more freecoil spring. This is not always true, but for the most part it is prevelant in spring design. I would rather see him go to rear coilovers with the plate design I aided Spohn in creating- plus the fact that Berk has already tied his cage into the rear upper shock mounts. Coilover rears would give us ride height and spring rate veritillty for alteration in rates yet keeping baseline chassis height. ....

.....Anyways, whatever his budget is, the rear ride ehight will be set based on the front height and then I will have to evaluated the roll centers front and rear and the overall roll couple and attitude of the car in roll.

Then, the rear contol arm (LCAs) angle will have to be evaluated, and if not desirable, provisions may have to be added to correct the angle to nuetral roll steer- and hopefully no wheelhop will be present- I do not anticpate any, but if present, I will evaluate shock compression settings overall on the car as well as all handling charateristics of the car and determine if I need to lower the angle a bit and bandaid fix other things to get the massive power down at lower speeds without inducung roll oversteer.

That formats a baseline I am shooting for before we even get into actuall shock valving, swaybar changes, brake bias alterations (Speaking of which, i gave him a baseline how and where I want his bias set for baseline), etc..

This is a serious project. I am aware and fully value the money I am asking him to spend and the time involved. i am taking this stance to help him in a completely professional manor with my reputation on the line. Everyone else of course is always free to give imput, but please do not make guesses at things when it comes to other peoples money. Changing and choosing springs rates is always for the most part a "guess" but I with my knowledge and racing history & resume reduce that guess to an "educated guess" based on my extencive experience not only with these cars, but with vast chassis geomerty understanding.


Dean

blyth18md

Do you at least know the vehicles current(actual) total weight? Or are we just taking a guess given the modifications performed thus far to deduce the initial spring rate starting points?

Not that they are far fetched by any means, I just curious as to how came up with the numbers so far, beyond just 'experience'.

Thanks, still trying to decide on rear springs for my car.

Guest

opps, hit the wrong button before finished typing- look for next post lower on page.

Roostmeyer

iTrader: (3)

Berk,

Sounds like you may have too much rear brake bias with the same pads all the way around, from what I've seen on FRRAX.com is that most people are running race pads up front and street or very mild dual purpose street/race pads in the rear. When you lower the car you may lose some antisquat and you should be able to dial a little more brake bias back into the car. Of course without good tires up front you aren't going to need as much brake bias up front as the people running racing tires.

I would highly suggest bigger tires and a better compound in your budget in addition to new springs and dampers. Kumho and hoosier both make tires that will work with stock 16x8's that may get you some much needed grip. If the budget supports it people have gotten 18x11's from CCW or 18x10.5 z06 wheels to fit all the way around the car with some work, but you won't be able to go that wide if you use extended ball joints and a bump steer tie rod kit. I agree with Dean that the inclined roll axis of a lowered f-body needs to be addressed for racing that involves turning more than one direction. Personally I'm not a fan of high RC's at all so I'd suggest dropping the rear RC to match the front with something like the PHB relocation kit from Unbalanced Engineering.

Dean, an 5"x10" 225 spring is "big" (and heavy) in my book, I run 2.5x6" springs on the daily driven miata, but its stiff enough that coil bind is not an issue. I'm not sure what spohn product your speaking of, but maybe something similar to this?: http://www.wolferacecraft.com/detail.aspx?ID=820

I don't have access to spring testing equipment, but I don't see the length of the spring having a significant effect (-/+ 10%) w/in normal working range (not the first 1" of travel and not the last 1" of travel before bind) or are you talking about the front springs? I've always wondered what affect the open end of the spring is having on the spring rate and spring motion ratio with the open end being on the inboard side of the a-arm. Are you suggesting running adjusters in the back but not the front? I think you need to have some adjustability at one end of the car; it might as well be the end that doesn't need an alignment after any ride height change. I personally prefer the all star adjusters over the ground controls in the back, but decided with my access to a large aluminum scrap bin that making shims were cheaper and still nearly as easy to install as cranking on adjusters.

How much driving experience do you have? I hate to question your ability but theres no reason to tune around a ham fisted driver that just needs some better instruction. I would check your swaybars for binding in the bushings and/or preload. Either is easy to overlook when putting a car back together and can really wreck havoc with the handling of a car. With all being right with the setup I would say too much rear rebound damping or too high of rear RC causing the car to be loose on entry, but I'll admit that that sort of diagnosis is alittle out of my league.

Guest

Baased on the differences in weight bias and cg of the V6 to the SBC V8 cars and the different spring rates and roll centers I have driven on, I can very closely assume the feel of Berks BBC car without drving it and compare that to the feel and changes I have made to mine and changes I have made to V8 cars and their characteristics from those changes.

now with that said, I have then conversed with Berk a few times getting driving data and vehicle data through private emails as to what type of car he likes and his driving line or style. Then He has told me how the car is reacting to that drivng style and what it does on a slow in hard out senerio in putting down that power as it sits right now. He hade some shock adjustments and gave me back further input as well as some braking tips and brake bias aterations and its affect under loaded AND unloaded braking.

Now basing my experience of weights and spring rates on what I do have and what I have driven on and seen in SBC V8's in comparison- I also factor in that not only is the BBC larger in weight than the SBC, it is larger in size. What does this mean? taller roll weight and even greater bais diffenrence front to rear since off the trans the BBC reaches farther forward in the engine bay than the SBC- and my old V6 even less... its all proprtions.

Now with proprtions comes vehicle charateristics and weights and consequent roll cenrters taylored to those factors AND THEIR DYNAMIC CHANGES (very important point). The heavier the nose of a car the more a cantered roll couple will make a car roll over onto the outside front tire.....so we have to control the weight and how it rolls and dives. This takes knowledge on the cars "feel characteristics" through experience with them. "I have that exprience" in many many cars and a truck or two . I had a few friends of mine Mitch and Sterling) that I have done extensive work on their SBC Camaros. Mitch had the Prokit and Sterling I did a few different spring rates on his 327ci Camaro putting down about 500hp. I ended up with a car about 25 3/4" off the ground with stock suspension geomerty (no alterations to front roll center (RC)other than the normal drop of it through lowering geometry) and 950 lb front and 175lb rear with 36/24 bars (Thats the bars I had to work with Mitch should have gone down to a 21 or 19). Both of our cars very closely matched in spring frequency slightly on the higher side than his but mine was greater in fequency or uncomfort level due to the Koni compression valving as opposed to his Tokico blues- but both cars were comfortably stiff suspensioned ( I only said uncomfort above for explianation of direction in comfort was). My car had 800+ front springs and progressive rears 160-225 and I ran a 34mm front bar and a massive solid 25mm rear bar. I also had extended ball joints raisng the front RC and the rear RC lowered by adjustment provisions added. I ran a front fender height of 24 3/4"
and I had a very lightweight nosed V6 car. My car turned circles on Sterlings when hard pressed into a hard braking slower corner. He had a delayed response to rotation until it rolled over and set. His front was good rear was not, His shock valving suffered. He needed more front compression, higher rear spring rate, smaller rear bar and a "slightly" lower rear RC Intall stiffer springs and start lower by prob 1/2"-1".

I have much more knowledge than listed, but thse two cars alone (so a much larger novel is avoided) for comparison in geometry specs/angle/data and weights and roll charateristics is a good model of comparison beween the two cars of a starting point for a BBC. PLUS the added experience of learning what I would do different if I started over on my car over years of changing things to get it right and the money I had to back that and do things correctly- what I learned in life is I have the knowledge, but now unfortunately do not always have the pocketbook to do things best. I have learned tricks in chassis dynamics. So yes, I have alot of untapped experience. I can make anything handle to its best- money is the limiting factor. How much money does Berk have for testing amd parts? that is up to Berks privacy- he has one heck of a car right now with pretty big $$$$$$ into it already so I think he may be game for more. I just know I can get him there as fast and as inexpensive as anyone dealing with a car nobody has every doine before with a BBC. Even the NSA and CMC guys and gals that race these do not have my knowledge because they set their cars under rules nd restrictions. My street car was much more a "racecar" than any of theirs by far other than I had no cage for chassis stiffness- but I had many other things they did not making up for lacking chassis points.My resume as a NASCAR crewchief also can tell you that is a racer knew everything about thier own car the car would not need a driving specialist and a suspension specialist otherwise my job would not exist- point being? sorry to sound harsh, but most racers in CMC and NSA so not know what they are doing. They all mostly talk about themselves and copy eachother and or the few that are in the know. I am a driver, I am a mechanic, I am a fabricator, I am an inventor,I am a suspension geomerty expert and I practice this everyday even with my daily driver street cars. I think this all shows with advice you all have seen me give on these boards. Why am I typing all this? Because I was asked how do I come up with an "educated guess" which I will say is a very good question so I am honestly trying to give a good answer out of respect to all. To give imput when you are not driving the car or even there to see it in person is a VERY DIFFICULT thing- I have successfully done this being a crewchief and have learned communication to a driver and have learned looking at pictures and data and making appropriate changes. You have to kniow the car in question- I know 3rd gens as good as anybody. berk is giving me data and pictures as well as feedback verbally to match what I see. I feel we can communicate and get this done.

Berk does not have his corner weights- I asked if he did. If so, we could figure his frequency range based on the motion ratio of .42 and I bet we would get a direct comparison in calculation to the V6 and the SBC if I had those corner weights also I know mine aprox because my aprox overall weight and my factory specs and additions.
Frequency though is merely a comfort tool- ride in a Cadillic and then try and race it (A bad shocked Caddy with float to much and make you seasick also if too low frequency). You NEED to keep freuency within reason of comfort range so as for the human body to be able to put up with it, but frequency has to be higher for better handling point blank. Alot of those calculators simply give a guideline of what the human body can endure, each individual choices his own level of comfort. Berk is certainly not looking to drive his elderly grandmother to the store in this car nor is he looking to tour accross Europe for a month in it.

So... with those examples and educated guesses, Knowing that a heavier nosed car will tend to make a 3rd gen push on corner entry into a snap oversteer and then massivve power is was loose off, and thne given the info he has given me on how his car turns in and what its doing as well as seeing the pictures of the chassis attitude in action and understanding of roll centers and roll couple with weight bias and dynamic loading changes, and based on my extensive experimentation (trials and errors & successes)- I can accurately guess to what baseline rates I want him to buy based on what he wants to spend on componants.

If he wants a basic budget build, 1100 lb fronts, 225 rears. If he wants a more expensive but better handling build? then its 1000 lb fronts and 225 rears. I am going to need shock valving to get this dialed, but for now we need more inportant parts since his Tokicos will pass for now for some future comfirmation testing.

To try and teach everyone what how and why I am going after those rates and what I am trying to get the chassis to do is very complex and who involve most of you to go to a college course for 4 years learning this crap. Its very complex. Basically in few words. I am trying to take weight of the nose laterally and transfer it diagonally onto the outside rear wheel without loose off ORRRR (I emphysise ORRRRR) loose rotation ability by loosing grip on the inside front tire going into a corner. This is done not only with steady state balance of the chassis weighs, but also dynaically manipulating entrance and exit without compromising any of the three and maintaining good tire temps and comtact patches- all with a heavy nose probably 62/38 bias car range.

Guest

Roostmeyer, I just read your post. In quick response, I was merely giving a comparison example of spring rates and frequencies. thise exaple of free heights and free coils were not 3rd gen specific, was just trying to explain a point on spring design. When you deal with already higher frequencies in performance chasis', any increase thereafter in frequency gain through articulation is critical. The frequency AND rate can both build quicker with less free coils.

Back to my last post- in continuance where I left off-

1100 lb rates are needed to keep the car from standing on its nose under hard braking and rolling over on the outside front tire- this will dramatically help slow the car by increasing rear tire grip- but at a cost of corner entrance rotation. The higher the front rate, the tighter the car gets. The higher the spring rate the greater the loss of mechanical grip.

However, lets look at the overall picture.
Fact 1) Berk is loosing rear tire grip and is skipping or hopping the rear tires under any kind of substantial brake pressure.
2) He slows early and settles priot to entranceand is rotating easily into the corner- but slow, under hard brake he plows then bolts inward with the front steer, good rotation, just overweighting the front tires until they finally bite when slowed enough.
3) rotates through mildly fine, and has to lay the power down hard not to fall off the competition- Berk says sometimes the car is tight, sometimes it is loose coming off. In other words, he is exiting much slowier than the competition and spinning his wheels trying to catch them, he has his hands ful just fishtailing off under hard throttle- he can not use his power_NOTE: this is not saying he is loose off! One can fishtail in straight line acceleration with no lateral loading influence.

With a higher front spring rate, we need in proportion of course a higher rear spring rate for lateral balance. the inside rear weight will no longer be thrown diagonally onto the opposing front as much keeping more rear weight on the back outside tire laterally going in.

If he has later trouble coming off we can work on that with shock valving and stiffer posi springs in the rearend to tighten him up, as well as power management. The key is to get is corner speed higher as not to have to exit too slow and create wheelspin. I can also tune this in using the front swaybar and spring rubber combinations if the exit is too loose- he will need to later make these changes if needed to give me fine tuning. Don't think we will need them though.

This BBC in a 3rd gen is a real challange. There will always be comprimise. Heavy motors are an enemy of handling. However, this will be a fun car to drive and intimidate the competitors with all the power.

Dean

Guest

A copy of my last email to Berk. We are detailing the desired geometry of a third gen A-arm and the ride heights availiable in options.

...[Good Morning,
Great detailed picture of the underneath of your car. You have a very nice car to work with! Beautiful car.

Lets start with the steering linkage....it looks great. I am puzzled what the alignment techs are worried about? I have heard something about Europe has gone to some new alignment system throughout the region and they just do not have data on the older vehicles? Maybe that is just it, no one there has a manual spec machine anymore which would be sad. We can do it together using a magnetic angle gauge and some straight edges and tape measures. Not real precise like a computer alignment, but it will be plenty good enough to work for track use and light street use for tires lasting 10,000 miles or less. We will tackle this later after any setup changes we do.

Your A-arm angle does look good starting 'range' We could go more flat if needed slightly to get the car lower (lower car= lower cg [center of gravity]= good thing). I know that picture shows the current suspension BUT with the old rims- are they the same tire size as current? I am wondering about the new tires and wheels sitting everything maybe an 1" lower to the ground already more- with concerns of the oil pan and dual exhaust.

*I will need to wait for the measurements I ask for prior. I know you will need to wait until the weekend to do so. Once I know our current ground clearance I can go from there. I want that A-arm angle just a tad more parallel to the ground by 1/2" (meaning if you just take the car the way it looks in the picture and lowered the chassis 1/2" that arm angle is perfect. I want it just a little more laterally straight at stagnant than it shows in the pic.So if we do that with spring length (by trimming the springs- I will help you with the calculations of how much to trim off the spring with a cutoff wheel)we can do more with balljoint or spindle if we have the room. I will give examples of what will happen- it will decide on the measurements you give me of fender lip and ground clearance of pan and exhaust (basically the lowest point underneath the car).

----example 1) Lets say you are at 27 5/8 fender lip and 6" ground clearance right now- results= I would have you leave the arms at the angle they are with new 1000 lb springs and also have you install Racecraft 2" lower spindles. I favor the lower cg over A-arm angle (angle is good enough)
..Finished height would be 25 5/8" fender lip and 4" ground clearance with the higher spring rate to avoid grounding out and the identically same A-arm angle.
*This is my best choice* if we have the room to lower that much keeping the car at least 25 1/2" minimum. 26 would be better. (speaking of which- how tall are the tires you run? 25.7" ?)

-----example 2) 26 7/8 fender lip? then I want to go only 1" lower exactly because I can only get a 1/2" lower with a extended ball joint and then only want the A-arm angle flattening out by another 1/2" with a spring rate trim = 1" lower at 25 7/8 fender height even if ground clearance is NOT and issue and we have 6" after finished. HOWEVER, if that example 2 gives us only 3 1/2" ground clearance then we are too low ground clearance, but good on strut clearance and wheel well contact (tire not hitting in wheel well) so last option..

-----example 3) just trim the spring so the car sits only 1/2" lower to get the arm more flattened out in angle and go to 1100 lb springs because our roll center is lower than the other two examples+we will need a higher spring rate due to more leverage exerted onto them laterally.

What are our minimum measurements we are watching out for? I will give them to you so you know what you are looking for when you do your measurements and you have an understanding what I am watching for.

* want a very minimum fender lip height of 25 1/2" NO LOWER! Preferably 26" on the nose with the heavy big block. I ran mine at a very low 24 3/4" and I never grounded out, BUT, I was very light with heavy springs and only had max travel of 1 1/2" in articulation on heavy bumps! 1" normal travel. It was very low movement. your car will be moving still in the 2"+ range with the heavier engine frontend even though you have stiffer springs. I started my A-arm angle more flat but only slightly inverted. I had no gain, but no loss either. I want to build gain into yours. Racecraft did not sale these great spindles when I built my car- I would have bought them if I had the choice for mine. Just note that we need to keep you slightly higher though because you will still have more suspension travel than I did with that big block engine even with higher spring rates. Your vehicle dynamics are different than mine with about 60/40 range where mine was much closer to 50/50 weight bias.

*I would like to have at least 4" minimum ground clearance left over after the car is set to 26" range- if not, then we raise the car up and fix the A-arm angles accordingly to my scenarios.

*Wheel measurements and Tire brand & size (including height...ie 25.7" ?)

Take care for now,
Ask any question you want, I love to teach this stuff

Dean
PS- I attached you picture of the steering link with comments. Everything under there looks great even the mount heights and symmetry of the drag link,pitman, and idler arm. The Idler and pitman are both straight forward facing and the wheels look parallel to them- All looks great. Good adjustment range left on both sides of the tierods. Only thing I can think if the steering is off on rotation to lock both left compared to right is that the pitman was clocked wrong when it was placed onto the steering box -OR (food for thought) are you turning one way more than the other because maybe the spindle stops on Spohn's A arms are not accurate? its a possibilty. Best way to find out is put the car on turn plates. If you have access to turn plates then put both front wheels on them straight at 0* then turn left 10* with the right tire the inside left tire should read aprox 13* and visa versa. Now you can also see if one side goes past that to lock at lets say 20* and the other side goes the other way to full lock at lets say 24* then we know the steering stops are off and the linkage and steering geometry is fine.
I wish you lived close, alot of this stuff I could just check quicker than it takes me to type all this . ]

Roostmeyer

iTrader: (3)

Dean,

How much of the lowering did you do with the monoballs on your old car? For your 1 1/2" of bump travel was this to the bumpstop, LCA to k-member, or did you bottom the tire in fender well? I seem to remember you were running 245/50r16's. I know how important RC location/LCA angle is for camber loss in roll with a strut setup as well as weight transfer, but I've been building my car with the mindset that the extra 30+mm's of rubber under the car with an 18x10.5 or 18x11 and a little more static camber is going to more than make up for unfavorable geometry and a higher ride height in an autocross run. The only way to fit rubber that big on a thirdgen is to fit it under/around the outer tie rod with an 18” rim. For my car that won't be seeing a parking lot that often I don't see the loss of turning radius as being an issue.

How much do you think you could have dropped the lower balljoint before bumpsteer becomes an issue with stock tie rods? If it ever slows down at work I'm going to draw up some points in Solidworks and see how how much caster affects bumpsteer as well as the LBJ. I've got some old SW sketches from FSAE that would've worked great if the LCA's on these cars were parallel to the chassis centerline. I wish there was an easy way to correct bumpsteer at the centerlink instead, I'd love to eat my cake and have it to.


True vehicle dynamics courses are few and far between at least in the schools around me, but I wouldn't go so far as saying you need a four year degree in it to understand it. I think any math physics or engineering major can read Millican's RCVD, put enough thought into it, and with minimal experience apply it in real life. Its the experience part that kicks my butt from time to time. I will admit that some of the stuff you guys do for turning left does make my head hurt from time to time. For those reading these threads I'd start with Carroll Smiths books and work from there. I am not asking you to justify your spring rates, they look like they're in the ballpark and doing so would make this thread even longer...

As for racers NASA AI, CMC and SCCA ITE, ESP etc., I take 100+ racers advice as to what works at the racetrack very seriously. Yes their setups and experiences are tainted by racing by a rule set but their "testing" is against the same drivers every weekend with cars driven at 100%. They may not have the best setup knowledge but there are a few that are "in the know" that end up setting the bar for all the lemmings to follow. Even if its just through pure trial and error their setups are usually the way they are for a damn good reason, its up to the observer to pull the good nuggets of information from a rule driven compromised setup. I can't really defend them any more w/o getting into a flame war so I leave it there...

I think you may missing a big point here. The suspension setup is there to A) make the tire happy, and to a lesser extent B) make the driver happy. For a uncompromised race car, the tires he chooses to run are going dictate the desired roll and pitch stiffness sprung mass frequency etc. Have you discussed tires and alignment with Berk yet? With the added weight and power of a BBC I'd like your opinion on my thoughts of running a 305-315/30r18 racing tires on an 18x11 and living with unfavorable geometry and a higher ride height.

Guest

Roost,
The monoballs I had lowered me 1/2" just like the tierods I had also. I actually had another 1/8" shim under the Baer tierod adjusters making a total of 5/8" drop on them and 1/2" drop on the ball joint.

The caster I ran kicked the spindle upward so the extra 1/8" keep them in sequence in articulation with massive caster. I ran 5/5.5* l/r caster.

My arm angle was flat to begin with but my car was sooo stiff it had little suspension travel in straight line drivingbut would compress in corners an average 1" in roll. I use to use little cut zip ties on the strut rod to check height when I ran it in skidpad testing senerios to check body movement through shock travel just as the race shock come with o-rings in place for this very purpose. Its why I made the comment if I could have done things over, I would in a heartbeat go to the new Racecraft spindles to keep best possible camber curves like I am suggesting to Berk. No spindl;es were availiable when I did my setup, so I opted for lower cg with a tad loss in suspension geometry gt away withit becasue I never ran racing rubber on this ca and had street alignment specs- However, as stated many times before I was able to pull an amazing 1.07g's in this car so my camber did not suffer due to minimal body roll and suspension travel being a lightweight nosed V6 car. Its why I coulkd do things like this the v8 cars could not They would have to run so stiff they would loose mechanical grip.

As for your comments on 100+ racers experience doing things mostly the same and it works? I fully agree. I thought I kindof said the same thing so there is no arguement here. What I said was what we are doing hereiherk has no prior testing and research where as CMC and NASA have all the research in the world under their class restriction. If all so a sudden CMC rules were changed to a setup with a BBC like Berk has, you would see 95% of the feild laps behind scratching their heads as to where to start until the better guys setups leaked out over time. That goes with ANY racing. Unlimited is most fun. No rules, just pocketbook restriction and one mans creativity and trying to make that all work to its best- thats where I have fun.

My NASCAR thing I went right to the top in 18 races I got 2- 1sts and 5-3rds on my resume with the guy winning the championship having a 48 race history and a father that ran the series before him as well as many other pedigree team there like Johnson Jr whos team and sponsor is all owned by Kenny Shraeder. I was wet behind the ears 18 races ago in circle track racing- it was brand new to me. I took the kid to a 3rd in Championship out of 41 truck my first year while learning- but we had the money for testing and equipment which made the BIG difference and I learned my job quickly since I have such a vast knowledge of chassis dynamics. The new guy I am helping was so far out of wack I am trying to learn his equipment and bring this back of the packer up into the top 10 if I can- can I win with this guy? We do not have the money even for tires...so, am I having fun with this challange of little money and older equipment- heil yes! I like being the underdog and taking everyone down. The team I am still registered as crewcheif on has major politics going on with the new racecar shop as a sponsor wanting to run things since their name is on the car. They started doing that on race 4 this year. I have stepped back and am just keeping my mouth shut as they hang themselves- so I started helping out a backrunner and started actually enjoying myself again having fun. I dam near got this guy to pass my own driver in the last race which I would have been in big trouble for- yikes. We finished right behind Mason while I was working both pits. I did not expect that good of a climb from this new guy running race old tires last race. Oh the politics and egos of racing The larger the game, the more of it- lots of money on the line.

Finally, to you comment (respectfully of course) thinking I might be "missing the point" on suspension being ultimately for tire contact patch and driver feel and "have I asked him what tire he is running?" Look at my post near the bottom where I told him I will be needing tire specs (Brand, height, and size). How can I be missing the point when I am in the peliminary stages of just getting his chassis height and camber curve in order regardless yet of what spring rates we will use. I have not told him what rates to buy yet, I told him what I am possibly looking at based on what his #'s come to once he gives me those. I have my own speculations and I need him to verify the #'s for me so we can proceed.

This entire post stated out as to "What shocks should I buy" because Berk had asked in another post about his car and I mentioned Varishocks after seeing his BBC and the intensions he plans for it saying he will need a very good double adjustable for what he's doing- OR he will have to keep diassembling his car a sending out fixed valve shocks for revalving(what a pain in the **** that would be, not to mention his alignment would be off each time he unbolted those front fstruts from the spindles and then reattached them with the slop they have in the bolt pattern. I do not always type everything I am thinking because the novels I write are too large as it is. I try to get to what matters, then low and behold I have to explain to everyone else everything to where this stuff gets confusing to read through all the text in this now massive thread. Talking to Berk from this new thread, I told him to wait on those right now becasue he has much bogger priblems we need to fix first. So... with that said..

...I think you need to slow down and are missing th epoint on just how inportant baseline chassis setting are before we even get into spring rates, shock valves, wheels tires, rear diff, polar wieght and placement of movable weight distribution for bias and cg,etc....Roostmeyer,back way up and jus think of things right now as a chassis and body with a BBC put into it, a trans, and solid axle we still need to attach properly base on how we can start setting up our Mcpherson strut front end with the limitations of factory A-arm ears on the chassis-- thats where we are. We are going to basics first, not bandaid fixing them later becasue we overlooked them like most people do. We are utilizing the MOST of what the factory chassis specs can give us with geomerty regardless right now of what motor is in it, or what tires he will use. or what shocks, or what steering wheel...speaking of which..Hey Berk, you better get a horn baby! You'll be using it getting those slow **** AMG's out of your way.

Guest

I camr back in here seeing if you responded yet and just reread this again. I did not really catch his the firs time so let me quote you here and ask why you contridic yourself even? You started by saying you think "I" am missing the point, then follow that up by sayingthe "suspension setup is there to make the tire happy".....ok....but then...
you want to put the car on wide tires with unfavorable geometry? Can you answer yourself if that tire would be happy?

Before you further answer this or anything else, remain yourself first and foremost that "suspension geometry" involves a combination of both static and dynamic placements combined. You need to stop thinking of contact patch in just max corner grip and think also on straight line braking, corner entrance and corner exit, as well as accelerartion. A racecar is 95% or more at these points of a track and only at max grip in steady state maybe 5% of the time at most. Stop focusing on just max grip laterally. Unless you are in a high speed sweeper or in circle track, count the actual time you start to turn the steering wheel to when you steady it at max grip, then count how long you are at max grip, then count how long you are releasing the wheel coming off a corner. When you are at max grip on a road course, for the most part you had better not blink or you will miss couning that portion. I did a post on here a few months back on "yaw ratio" in corner and how it breaks down vehicle dynamics and driver comfort. At Toyota Speedway we are at max grip laterally of about 2 seconds on 20 second laps. Most of that time we are under braking and turnin, or under acceration off apex exit. If our contact patch was unfavorable for 18 seconds and only perfect for 2 we would be in trouble and would only be running about 22 second laps becasue we ar not hitting that favorable 2 seconds at optimum entrance speed or exit speed due to loss of acceleration time and loss in braking time.

I think I made my point. The tire contact patch has to always be the best even in straightline. You guys that want to compromise static contact patch and start with too much neg camber on the straightaways are going to finish back of the pack every time. giving up 95% of the time trraction loss (or 90% in circle track racing)

There is only one lowest geomerty setting that is optimum. Add 2" drop spindles and place the a-arm in articulation range for about 3* roll and it will be level to the chassis for most camber curve gain on a 3rd gen. What spring rate will constitute 3* roll? depends on the vehicle roll weight and the grip coeficiant. I have already seen the wheels and tires Berk has. I am trying to fine tune my spring rate decissions based on his BBC weight and my knowledge of grip of various tires and 3rd gen combinations. Is there a bit of a guess involved? heil yes- I said that from the start- its and educated guess. Think anyone can do better? bullsh*t. Even the big boys of NASCAR with all their syphisticated equipment and millions for testing could not get the new COT NASCARs correct out of the gate and where struggleing and placing all over the feild the first year till they goot actual track aquisition data on the new cars, regardless of the weights and data for the old NASCARS that they had charts on for some 40+ years in some cases. You think the pros don't guess? guess again. But its an educated guess.

Roostmeyer

iTrader: (3)

Sorry those two should've been in seperate paragraphs. What I meant to bring up in the first part of the paragraph is that the tire affects everything else in the setup so why is it the last bullet in your email? Without knowing the tire you can't even take a swag at the target peak lateral and longitudinal accellerations. You don't know how much roll stiffness or pitch stiffness you want/need, then you can't choose a ride height that will keep you off the bumpstops. If you don't know your ride height, how do you know you need to mess with LBJ's to move your roll centers? I know your experience with the chassis can answer ALOT of these questions for you and get you in the ballpark, but the setup is going to need to be different if he's got the budget to put good rubber like a Kumho XS, or perhaps the best rubber for a single lap time trial, the Hoosier A6. This isn't even getting into what type of wheel rates the tires can deal with before they're overloaded.

You may only be at max lateral grip for a brief instant in each turn but I sure hope your driver is going to be at max grip on the edges of the traction circle for a lot longer than that. More rubber is going to help the car in all phases of a turn as long as its close to happy. With a strut setup the best we're going to get is a negligible amount of camber gain in roll anyway. Negative camber gain isn't always a bad thing, with the average Herb Adams inspired setup with soft springs and lots of front bar the car is going to compress the front suspension more under heavy braking than it ever will in roll, gaining back some camber and keeping the contact patch more level under braking than under static conditions. Heck it might even gain some camber when the front end lifts up as I roll in to the power on corner exit. I would definitely want to avoid trail braking entirely though but I think I can adapt as a driver to get the front end back up before turning in.

I still want to lower the front lower control arm, but I'm more concerned with being able to gain more bump travel and lower the car more if possible. Raising the front RC some would be a very nice side affect. As for RC's being out of whack I'm planning on dropping the rear RC with an unbalanced engineering kit or I'll make my own. I'll be giving up a substantial amount of roll stiffness, but with big bars I shouldn't have to get to extreme with spring rates to get the roll around or under 1°/g. If all else fails I'm ready to raise the front of the car back up closer to stock ride height. If I were starting from scratch I'd shoot for 50+% of the roll stiffness from the springs but with the poor spring motion ratios on these cars I don't think the tires and the driver would like it very much.

There are always compromises in any suspension design, unfortunately for us a strut based suspension is going to have more compromises. I agree with you on the guesses. I think the best you can hope for is getting out to the track and have a driveable car at the limit thats still far from optimized.

I've been spending some time in the rollrates spreadsheet from frrax, but I need to take some time and go through and make sure all the data in it is correct. The more I discuss this with you, the more I want to get the suspension modeled up, it should be very informative as to whats really happening in bump and roll with FAP's as well as casters affect on bumpsteer and anti-dive.

What were the front RC heights you saw with your setups? I'm guessing I'm around 3-4" with a a 26.5" fender height.

Guest

Have you bothered reading what I have posted to Berk? or are you just so self absorbed in your own car's agenda? I thoought this was Berks post and we are trying to help him.

Partner, I can not understand at lewast 1/2 of what you are saying and the half I do understand I can't figure out why you insist on posting it here. Maybe you should start your own post about your car? I think you know just enough about roll centers to be dangerous to yourself.

i suggest you start from the beginning of this thread and read all of the information, then look how redondantly silly your questions are to me when I gave all the info on every one of them BEFORE you have even asked me them.

if you think you know roll centers, Then answer this simple question to someone that does- what part of the 3rd gen alignment affects roll centers? (these foolish questions in no way help Berk and just clutter this thread like I asked people not to do.)

Roostmeyer

iTrader: (3)

I know this has gotten way off topic, you challenged my statements so I thought I should back them up.

Why I brought this whole thing up is I agree with you on some of your points, but I think keeping some compromises in the geometry, even raising his ride hight will be more than made up for by running larger tires at all four corners. I've been trying to justify my points, you've been justifying yours. Problem is its still just bench racing at the end of the day. I've learned some things, and done some deep(er) thinking on the matter. I just hope we haven't got Berk too terribly lost.

One of these days when I have a legitimate reason to make a thread I will, until then I'm just going to keep spending my time wrenching and getting my car back on the racetrack.

engongam

Hello,

I wanted to tell you the progress...

I replaced my oil pan and we are ok about the clearance. I did my shopping=) I bought QA1 double adjustable coilover kit with 225 lbs spring rate to back. Yellow koni's (qa1's and varishocks were extremely expensive...). 2" drop spindles from racecraft. Extended ball joints from QA1, Jegs Panhard bar relocator and finally 1200lbs Eibach front springs, ...

I changed all suspension bars with Spohn del sphere double adjustable bars (LCA,Panhard, Torque arm)

Now what I am asking from you is how those differences effect the car? For example, I changed the distance between rear tires and front tires (I equalized them with computer alignment) The car felt very bad, It was all over the place, front nose dive was ok but rear... omfg. I was changing lanes very rapidly and rear felt like a snake, It was comming after the nose enters, It did not feel rigid. That is what I experienced.

I want to learn what lowering the panhard bar does to car or incresing the a arm angle, or incresing the rebound-compression values of the shocks...

Help me out=)

Thanks...

Flip 2

iTrader: (1)

Phew, a fine nest! A friend of mine likes to cite Mike Hailwood, infinitely adjustable means an infinite number of ways to get it wrong.
Good luck. It may be as simple as too little compression on the rear shocks. Then again, with everything changed around.... it could be the whole package needs setting up.
BTW, watching the Watkins Glen NASCAR race last Summer, the commentators (the car professional ones) started talking about axle tramp going hand in hand with gobs of power. A light flashed in my brain remembering your posts.
Forgive me for bringing it up now, but an LS6 could do wonders for your weight distribution....... 250-300 pounds less up front.
You have to be one brave son of a gun, hustling your car around.
Again, good luck, we are rooting for you.

engongam

After installing those parts, I will write every single change and effect on the car, maybe that would be helpful for other projects.. But I have no idea where to begin the adjustments... I should fix some of the parts and change one by one so that I can see the difference.

Guest

Hi Berk, I got your text today, I just sent you the email response. I will also copy and paste that email response here.
------------------
Hi Berk,
I got you text today so I checked this email like you are asking. My emails sometimes go to spam folder for some reason. I have a new computer for the last 4 months.
I just tried to call you and your father answered- very nice man. He was thanking me very greatful for helping you learn. He said you were in school right now for a few more hours so I told him I would just try and email you to get more questions answered about what you changed and what you felt.

1st of all- I need more specific details about what your setup is. He is what I know from what you told already...
Front- 1200 lb springs, Koni Yellow struts, extended ball joints (I need to talk to you more about this- you need this OR drop spindles, not both- I need to know how much you have them shimmed from stock ball joint height and where is your fender lip height from ground in inches), I think you have aftermarket strut mounts (Hotparts, Spohn, or J & M)?, Spohn A-arms. Sway bar size? (I do not remember this, please tell me again)

Rear- 225 lb coilovers, QA1 shocks double adjustable (where do you have them set? both compression and rebound at minimum to start? or mid level starting point? What are there adjustment range in # of clicks or revolutions? My QA1's I own are rebound adjustable with spinner dials on the lower shaft, I count the holes moved. I run mine on my truck on 10 of 1-12 in the rear for example), what rear sway bar size do you have?, Spohn Delspere LCA's and panhard. Spohn TQarm, Do you have LCARB's installed, if so then are your LCA's parallel to the ground at stagnant ride height and half a load of fuel aprox? (The rear of the LCA's should be as high as you can get them compared to the front without wheel hop on acceleration) WHy? TO help induce roll understeer so as not to have the rear axle steer outward entering a corner and the car go loose and spin out easy- this might be your current problem!)

Dropping the panhard rod mount height will tighten the rear end of the car in steady state, raising the panhard bar will loosen the car balance at steady state. Lowering it makes the steering wheel feel heavier to turn. Think of the panhard bar height as a breaker bar trying to loosen a bolt. The longer the bar, the easier to turn the bolt. The lower the panhard bar
is its like the body leverage is a longer breaker bar acting upon the springs sideways.Lowering the panhard in essence makes the spring rate softer, and vica versa when raising the panhard bar in essence makes the rear spring rate higher. Lower rate equals grip, higher rate equals more weight resting on the rear tire which equals more loss of grip.

A=arm angle? You just want this to set with the bal joint slightly lower than the a-arm mounts soi as to allow for camber gain in articulation. Too low will misalign lateral geometry. Too high will reduce camber gain and result in camber loss once parallel is breached.

Shock rebound and comression values.-
Think of the braking force as front compression and rear rebound.
Think of the acceleration force as front rebound and rear compression
Think of left corner as left rebound and right compression
Think of right corner as left compression and right rebound.

The rebound controls body roll fore, aft and lateral
The compression weights the tires. More weight equals more heat and sooner tire grip loss. (Just like higher spring rates) You basicaly want to workk with a car to figure a roll rate of about 3* body roll whil controlling nose dive and anti squat. TOo much control looses traction, to little control induces too much chassis movement and loss of transition speed.

Dean

TEDSgrad

iTrader: (4)

So I take it that the ride height was a little higher, which helped with the QA1 rear coil over height.
With my height I bottomed out the QA1 Ds703's.
Looking at Varishock vas 11111-515 or 615's for replacement and this thread title popped in my search - yeah, people do search!

SlickTrackGod

Hi Brian. To update this old thread- Berk is from Istanbul Turkey, I am in So Calif (USA). 8 months ago in late 2014, berk came to So Calif to further his education at UCLA. We have become best of friends and actually are partners in a budget race car (I put him on my NASCAR truck team).

As for this car? It has become a BEAST to say the least. Both of our hopes in to have me fly back to Turkey with him in the near future and I will personally help him shake down the car- then we hope to rail the car up to Germany and run it on the ring (Nurburgring). His family is coming out to USA in 1 week from today so we all can get better acquainted. I have been invited to fly back with them and say in their home for several weeks as their guest. (It may be several months pending a great job offer Berk has from a US company now following his finishing school.

Here is the car as it sits today in Turkey. It has a full cage installed and lots of electrical dash work for track telemetry by a European race shop.

The last photo is Berk and I co driving our Dodge neon Enduro car just 3 weeks ago @ Toyota Speedway sitting on pole out of 28 cars. This is a car we threw together to have fun with and destroy. May it be a lesson to all that great friendships can come out of the internet. I never thought he and I would ever meet in person 6 years ago when I started to help him build his car half a world away. He is officially the 1st Turkish red neck in History

TEDSgrad

iTrader: (4)

Wow, a motor... with a car attached!
What is that image on the license? Looks like a man in a boat, maybe it's just the flash.

Did Berk mod the drop spindles or keep as is?

I've always wanted to visit Constantinople, oops, wrong century (haha).
Westwood - now that's 'westernized'

engongam

No I did not do any mods on the spindles. So far they've managed to survive... Lots of things happening both in my life and on the car simultaneously. The car is constantly changing with the added new parts. It almost become impossible to keep this thread updated because I am not able to keep up with progress that goes on the car. I am here in US, my car is in Turkey. And it might be the only thing that I miss...! (except family and friends)

I'll sum the progress when we fly back to Turkey=) when i touch hands on my car...

TEDSgrad

iTrader: (4)

Hi Berk,
Good to hear everything is working out wonderfully, AND you have a job offer!!
I sent my spindles back in, they took them completely apart, and gave me the "road race" version I thought I had purchased all along. Cost some more $$, but I'm glad to have them and they are beefy. Here's some informational pics, they only come unfinished which is preferable so I can visually inspect much easier.

TEDSgrad

iTrader: (4)

Couple more, just so you have a reference, for whatever it's worth.

SlickTrackGod

I am keeping Berk occupied with a dodge Neon here in the states. Us last night winning the partner Enduro @ Toyota Speedway in front of a packed house of 7000 fans. We has 32 cars in the race. berk drove laps 1-15, I drove 16-30.

He is learning about suspensions big time with hands on training here in the US

(pic3-Me and Berk getting "hands on" experience.)

SlickTrackGod

Bringing this old thread back from the dead.

Update. Berk and I have become very close friends. We talk weekly and he and his family (Mother, father, and brother) have become like family to me. When Berk came to the states I took him under my wings. His family flew out several times and we have had a few dinners together every time they were in town.

As it turns out, I have been invited to stay in their home in Istanbul and will be flying there this summer 2017. Berk moved to Minnesota for a career, but with some visa issues he is back in Turkey working for the US based company for a year and then will most likely return to SO Calif where I am to live permanently. During his time back home, his father called me and has graciously invited me to come stay with them for several weeks which I have bought my plane ticket and am excited. Berk is currently working on the car and doing some testing as we speak.

Last night (which is morning for him) we were on the phone several times doing some more tweaking on rear geometry. The wheel hop has reduced dramatically but is materializing back a little as he makes the brake bias and geometry tweeks to tighten the rear of the car - so we are working on a little higher rear spring rate and getting the panhard a little lower to compensate. I am having he stuff the driveshaft as far forward into the tko600 as he can without grounding out the yoke. This will shorten his wheelbase and with the use of coilovers we do not have to worry about spring alignment. What this did is shorten his leverage of the springs so this is why the wheelhop is coming back a little. The inverted thrust of the axle upward upon braking forces is harder to control the shorter this is- however, this helps with chassis weight bias and corner rotation so it is the direction we need to go to improve the car's abilities.


Anyways- when I get out there in a few months, hopefully we will have a variety of parts at my disposal and I am personally taking the car onto his local track to shake it down. We also have plane tickets and accommodations to fly up to Nurburgring/Nordschleife during my stay there- my bucket list dream. There is a strong possibility we can get his car on a rail car freighted up to Germany (He is checking on cost) but this will also be dependent on how the car feels at high speed when I get to Turkey and make some tweeks. We are also reserving a ring rental race car so even if we have his car there the other of us can drive a second vehicle- or in the event its our only choice we are not stuck in an average joe car.

The front of his car seems to be working very well with the 1000 lb springs and the higher roll center. The car has lost all of the massive canter it initially suffered from several years ago.

More to come

ps- I turned Berk into a reddneck while he was here. (First pic)

ps- We've even been skiing together- He never mentioned he was on his countries national ski team and ranked #6 in the world in juniors competition several year ago. This has turned into a great friendship.

SlickTrackGod

Just some texted pics from him to me this week of the race car.

TEDSgrad

iTrader: (4)

Great to hear! I like resurrection threads!

I did not have much luck with the QA1's - performance blahh, range was off, blew the seals.
If I recall properly, Berk has a staggered set-up (8" fr, 9-9.5" back) w/iron BB. How is that affecting your suspension set-up approach/philosophy? I have considered it, but just can't move off the 4 square philosophy. I do think it looks good, and is not completely bad for a street car, but Berk's is race.




I switched to RideTech's HQ 6110 with #250 and a smaller 19 mm bar from 24 mm. The MW 12 bolt added about #30, though. Very happy with the set-up.

Orr89RocZ

iTrader: (20)

Have you looked at viking shocks struts lately? They now offer road race valving options. Curious how they make work for a double adjustable at fair price point

Also a fabricated 9" housing with lightweight axles and aluminum center, they are as light if not lighter than a 10 bolt rear

TEDSgrad

iTrader: (4)

Viking/QA1 are twin-tube
RideTech HQ 6110 are superior:
Features

1.) 1/2" hardened shaft is precision ground and straightened to a tolerance of .001" inch for increased durability and performance
2.) Billet end cap with integrated debris wiper to prevent seal damage
3.) Integral internal bumpstop eliminates extension crashing
4.) Teflon piston wiper allows consistent piston/bore contact and repeatable performance
5.) Specially contoured composite gas separator cup optimizes dead length and ensures proper nitrogen/oil separation
6.) Mono-tube design allows large piston for superior oil control – increases ride quality and handling performance
7.) Oversized rod guide improves piston rod stability
8.) Mono-tube bore is cathode anodized for years of wear resistance
9.) Hard coat external anodizing ensures years of lasting beauty and performance
10.) Mono-tube design not only optimizes performance but uses fewer components than a twin tube design. This is superior fluid control in its most simple and efficient form!

As for the 9" - yeah, done right they're great but also pricey. I was generous with the #30, and I don't mind a little in back down low. I did get Big Ford Housing ends, Master Line axles, TrueTrac!


Berk and I have similar suspension components, but have different set-up concerns. I doubt he still has the 10 bolt with the BB.

Orr89RocZ

iTrader: (20)

Yeah my strange 12 bolt is a heck of alot heavier than the 10 bolts lol but i guess its weight in the right spot? Better for 50/50 balance

SlickTrackGod

Important part of a staggered setup (I have the same on my Brabus Mercedes) is having the outside edge of the tires at the same track width. THis way they track the same grip edge in a corner. When one is inside or outside of the other in path of travel then you have to overcome an inherent push or loose condition in braking and acceleration. Tread towards the inside helps with keeping the car tight on corner exit when power is applied- He needs this without the unwanted outer stagger that would tighten him down on corner entrance. The big block wants to canter roll the chassis so everything earlier would go over the outside nose and the car would plow to a point of snap oversteer whcih is already the characteristic of any 3rd gen in stock form. This just enhance that inherit defect even more. The use of the drop spindles and extended ball joints got the front RC up where it is not cantering like it use to. The Kmember has lightened the front a little which in his case is good because he has such and tall AND low motor (ground clearance wise)- Most cases I recommend against loosing lower weight in the chassis below the roll axis. Here we needed to get the nose of the chassis lighter any way possible.

I still want to get hhis rear RC down more to completely eliminate canter from the inside rear lifting up into the air. This tightens the car so I need him to move the rear wheelbase forward as much as possible and incease the rear spring rate to keep the rear suspension at a very stable ride travel. I am working with him to eliminate wheel hop but also try and keep some roll induced understeer into the car so he can steer it a little with the throttle and have some slip angle. This will also help with rear jacking and the axle squatting up into the chassis as it lifts from the notorious rear jacking these cars suffer from. I have him running as much front caster as he can to help reduce the jacking effect through the strut angle. He is almost maxed right now with rebound settings so I really think better shocks will be needed (hence the 8212's).

All in all, I will need to drive it myself to really give an answer- half the reason I am flying over there.

I also asked hoim not to trim any welded on bracket yet. Wait until I get over there and lets do some testing first- then we will shave what ever weight we can off the rear axle- including running his rear shocks upside down.



Orr- Not the place you want to add weight. You want to add sprung weight, not unsprung weight.

SlickTrackGod

Also, My old car materialized in Long Beach Calif- very close to me. The ex finally sold it after it sat for years and turn into really a piece of Sh*t. I was looking to acquire it through 3 different shills but after the spy photos of just how bad the car's condition had become from neglect and dishonest mechanics she fell prey to- I did not want it. Some illegal Mexican has it down on PCH (Pacific Coast Hwy) in mid town Long Beach. Guy probably has no clue the history of the car of the exotic parts under it. It has been sitting on the street there like it is abandoned again...lol Tow truck ripped the spoil off it before she ever sold it. Doubt she got 2K for it because she didn;t know how to market what was under it- People saw V6 and thought NOPE. The paint is rotting off it. this pic actually makes it look good...haha

I doubt I will ever buy another 3rd gen. Been there done that. I still enjoy helping others with theirs because I love the cars handling abilities. I have other projects I am building.(slowly, lol, just been busy in life with other stuff like helping my best friend all last year extensively remodel a home he bought.)

This pic is from 2 months ago- Aprox Jan 2017

prossi

definitely not weight in the right spot

TEDSgrad

iTrader: (4)

Allright, I'll reconsider the wheels. Whenever I get around to doing the h/c/i, I should be at 500 rwhp. I have time to consider.

I don't recall Berk showing what kind of TA set-up he has. And what kind of caliper - fixed or floating? My personal preference is for the floating in our cars.

I know you prefer more bar/less spring on the rear. I'm the opposite. Detroit Speed offers their JRi's w/#275.

I hope you have some data logging to share when you hit the 'Ring.' The car looks good in black with gold wheels.

SlickTrackGod

Calipers are Wilwood fixed. Floating is not good for racing- Having a caliper floating on guide pins under more extreme heat will cause uneven pressure on the fixed pad side (the backside pad in the caliper) and causes uneven pad wear and hang ups (pad dragging). Pad run out is still about the same with either and you just learn to pre-stab the pedal to make sure pads are next to the rotor before the next braking zone with any type of caliper/rotor combo.

Hos rear end is a 12 bolt. That Ramjet502 would grenade a 10bolt. he's putting out 502 HP 558tq into a Tremec TKO600.

The car's rear has issues. He finally did a test drive last night onto actual roads. The initial testing was only done a few nights ago up and down a little industrial street checking on the brake hop, Really no cornering other than what data he had from two years ago on the track before he had motor issues and it went down for a rebuild.(He had oil pan issues last time on the track with cavitation because they had to modify the oilpan. The car now has the Accusump)

His panhard angle is way out of wack. He was 4" lower on the axle side 8.6" off ground to center of bolt) then the chassis side of 12.5. Car was a little tight, but also his main problem is he has the LCA.s too low in the rear. Car wants to step out due to roll induced oversteer. He is disassembling the rear LCS.s and shortening (grinding) the weld in thread bungs) to get a little shorter length because the rod ends are grounding out- thus he can not move them up to level them with the shorter wheelbase. I told him to make sure he has at least 1/2-5/8" threads left inside- if not then increase the wheelbase a little back towards OEM.

Panhard angle is terrible. I will need to buy a chassis side relocator and bring it over in my suitcase so we can get the panhard level. The test drive last night the front fet very good he said (his quote was the front feel's "On point" and there is absolutely no inside rear canter of the chassis lifting. Braking feels very good and no wheelhop. Car was just a little too tight and had to steer with the throttle.

At this point I told him I wat him making one change at a time. Get the LCA's up parallel at static so e can induce roll understeer, not oversteer as it is now. THis will tighen the car a little more even. Then next test drive is to raise the panhard one click and drive it, then one click again and drive it, until it feels good. If he has to go back up more the one click then I am concerned with the chassis canter returning and the wheel hop may return a little. If that is the case then we up the spring rate in the rear and get the panhard to that lower position without the tightness.... If one click does in fact work but car goes a little loose on track day with hot tires then move the rear swaybar axle mounts in closer together width wise to reduce the effect of the rear bar.

Here is a quick little test of the motor outside of 1st and second gear. The first real road test of the car in a few years of sitting while he was in the U.S. - Note like I said the car is tight and then goes into roll induced oversteer. He is working on the car right now (he just got off work- 13 hr time difference) so maybe some more vids to come soon. Berk is a damn good driver for his age. I am teaching him more discipline on making a car last. he has yet to match my lap times in any car we have co-drove and it is bugging the crap outta him...lol I think I am going to be treated as a god in his family and friends circle- he is quite popular in Turkey and I have a lot of them now on Facebook who can not wait to buy me rounds of Raki (god help me).

skinny z

That has to be quite the sight on the Turkish highways!

TEDSgrad

iTrader: (4)

The QA1's he has, has a range of 16" - 13" collapsed and 19.5" extended; so he's probably keeping the ride height up there to keep from bottoming out. This contributes to the LCA's too low in rear. Maybe the 8212's will have a better range and allow the rear to be lowered some. Rear tires same height? Pics can be deceiving, but it looks like generous sidewall for an 18".
The last pic in post #39 - the sleeve adj. looks about right, though.
Here's a pic of mine with the 12 bolt in, but before the bar and RideTech swap. Just about the same sleeve thread amount. Car is on the pavement and my LCA's are much better than his, but still angled.
I just went out in the garage and looked, after the RideTech's are in, I'm using the same bolt hole and my LCA's are perfectly level.
I'm betting a shock with the right range and ride height will fix a lot of this.