Stephen

Quote: Originally Posted by Vetruck If you were anywhere close understanding this info I have posted then you would already know how to answer your own post. You would also realise that no one can answer this question except you. you will have to read and learn. Then simply type in "coil springs" in the google bar. Nothing custom about it. Coils springs are ready made in all rates- nothing custom made needed. People might think I am an *** for responding like this, but really folks, I spent hours typing this info for free and then I get a silly question like this from a guy with a masive heavy stereo system in his car...go figure. Do kids even think nowdays? (Kids in general, but not always the case. I used to think there was no such thing as a dumb question, but after reading a thread like this and then asking that?....Just lazy stupidity.) Somebody apparently forgot.....Once upon a time, they too knew nothing, nor how to navigate to web to find stuff.

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RU1NER

I did search and found sites that sold eibach, moog, etc nothing with a high enough spring rate. Iv'e also since decided to get weight jacks. And just because I have a stereo doesn't mean i don't want my car to handle at all.

Vetruck

The most important part of basic geometry, its where your head "BASICally" hurts.

keep in mind that when the spans, levers, arms, whatever, etc etc that are connected to the chassis and are articulation in fashion to the ground in the graph above- the chassis is pitching yawing and rolling also- which means the center pivot point of all spans are moving while the span is articulating.

The ULTIMATE GOAL of any suspension is to keep the tire contact patch as large and equal on all four corners. Albeit, this will not happen with dynamic weighting of the tires from the chassis under braking, acceleration, and cornering motion, but the two tires perpendicular to that motion must try to remain equally weighted to equalize contact patch. Suspension atriculation geometry is watch also keeps the contact patches as large as possible keeping the best footprint on the ground, AND lastly, the shock valving is what helps keep those contact patches constant and not bouncing up and down like a basket ball would touch and leave the ground.

How do we know what the contact patches are (in terms of lets say sq inches)? We really don't unless we drive onto that piece of glass in the old Goodyear tire commercial (see pic). We have to use acquisition data to come to conclusions of how the tire contact patch is via use of tire pyrometers that record tire tread temps accross the tire.

here's the kicker- jow do we know then that we aren't just running on the inside half of the tire on the stright and the outside half of the tire in the corners? Thus making even pyro readings accross the width of the tire- we don't...unless we do separate testing. You can test temps on skidpads where the tire is run in duration in a lateral set. You can record suspension travel with shock travel indicators to see where the chassis roll is in degrees, and then with the camber set for even pyro readings in a corner you then drive just back and forth a long road straight several runs without hard braking, acceleration or cornering- just speed up and slow down mildly and do soft u turns several times- then jump out and quickly take pyro readings seeing the straight line flat footprint at static ride height. you may find out real quick that once you have the car taylored to the corners, it does not set properly on straight line traction. This is where balance of weight bias, camber gains, spring rates, and chassid rigidty come into play. You start readjustng what is lifting and what is pitching, yawing and rolling dyanmically to keep the chassis (suspension contact or pivot points)in range of maintaining good contact patch. Its all about the tire footprint.

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madmax

Well as advised I copied and pasted the text "coil springs" into my google bar and the first two 'valid' responses were

www.coilsprings.com/
www.springworks.com/

And the list goes on from there.

madmax

In a static situation this is pretty easy to determine, its in a dynamic it gets really cloudy and the tire temp information comes into play as to where the tire is getting loaded.

RU1NER

If you want to keep debating this, I did see the second link not the first but decided i would go with the ground control weight jacks I guess i should have edited my question from 6 days ago that I figured he ignored.

Vetruck

Now that this informative thread is being cluttered up with bullsh!t questions that could be asked in there own new thread, gee lets see eibach comes up all over that search. Guess what you are probably buying from Ground Control with their weight jacks....ill bet Eibach.
Next you'll ask spring rate here...why not, clutter the **** out of this thread for your own personal questions- the Stephen will tell you "hey, do what I do and buy 600lb fronts and 150lb rears." What Stephen will also tell you is he is decent in photoshop but not an expert, however, Stephen is expert enough to lower his own car with photoshop because the Ground Control weight jackers and the 600/150 lb springs he has are collecting dust UNINSTALLED right next to the 4th gen double diamond SFC's in the hall closet that will not fit his car.

Yet, he will come into here mocking me.

blyth18md

Dean's my daddy. Lets not get his temper up. We all know where that gets us. If you're serious you probably have a few stock car parts catalogs laying on the end table already. If not google yourself some free parts catalogs.

RU1NER

I asked for a suggestion on where to get them I didn't say I can't find any springs. And about the jacks it says they work with Suspension spring specialist. And I never asked anything about eibach's. I'm really not trying to argue I asked for a suggestion you're to awesome to give one, end of story.

Stephen

Of course I will! You are so mockable! You singled me out in your post, in a useless attempt at achieving WHAT? To point out what is in my sig, so I am already 100% honest with every here?


#1......600/150s are my starting point & we'll see where I go from there. I already have 3 sets of springs to tune with on the rear.
#2......I've never said my sig pic was anything other than Photoshop, so it isn't like I am trying to pass it off as real
#3......I bought the KBDD SFCs off a member here on TGO, who claimed they were off his 3rd gen. After getting them, I realized they are 4th gen KBDD SFCs. And no....They are not in my hall closet. One of my house water heaters n.

And your point about my weight jack springs & SFCs was....WHAT?

RED_DRAGON_85

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RacerX13

Thanks for writing all of this Dean-it's really helpful.

I'm not understanding/visualizing this-

By the "ear" are you referring to the A-arm mounting bracket on the crossmember? Or the centerline of the A-arm pivot bolts? A pic would help.


Hope all is well.

Regards, Kris

Stephen

You so funny.....

I've been wrong before, have posted that I was when I am, and will be wrong again. That is just human nature.

You will be wrong sometimes, Dean will be wrong sometimes, everybody in the world will be.......Just the way life is!

RED_DRAGON_85

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//<86TA>\\

this thread needs a clean up of all the BS posts, it has a lot of good info, and its a shame its being filled with childish bickering

Vetruck

Hi Kris, I guess the answer is yes to both since the pivot bolt is on the crossmember/Kmember. Where the bolt goes through is called the ear. I am refering to that center bolt height in relation to the center of the ball on the balljoint.

ironically, I just answered this today on another post refering back to the graph on post #50 in this thread.
Here is a copy of that post .....
Re: front suspension/k member I will steal this graph I put on that thread earlier and I rewrote it specifically as an A-arm with the values you quoted me from that post.

-red= A-arm
-blue= balljoint
-gray= spindle
-yellow= strut
-black dot with orange circle= chassis mount point/pivot point of A-arm.

The first of three show the A-arm parallel to the ground. This represents the longest lateral measurement of the A-arm span in articulation. Represented by the thick black arrow at bottom. now compare the next two lateral measurements (black arrows at bottom of each graph)

The center example shows the thick red starting point of the a-arm. 1 1/2" lower on the balljoint side than the chassis pivot. In max articulation, the A-arm will travel 3" MAXIMUM, but a normal travel of 1 1/2" - 2" range. We really ultimately want the spring rate to allow the car to set 1 1/2" compressed to level in a hard set corner (without hitting road imperfections) and allowing for about 3* of body roll. This is your camber curve or camber gain. It alows for camber to increase negatively as the body rolls and produces positive camber. In other words, lets say you start with -0.5 stagnant. Then in a corner with 3* body roll you would have +2.5 camber- however, witrh the A-arm camber curve you gain -4* camber in that 1 1/2" travel so at full set you are now at a combined total of -1.5* camber in lateral grip.

Example 3 shows bad camber loss all the way though articulation.
Example 2 shows gain then loss in extreme travel-however, usually in extreme travel no more body roll is present, only the tire is lifting quickly over a bump in the middle of the corner. the last extreme 1 1/2" travel does not in my book require camber gains if the chassis is set up with the proper travel limit through spring rate choice (spring rate choice depends individually on each car and weights)
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Vetruck

This week I will get into distortion of contact patch(slip angles, and sidewall integrity) and how they pertain to pyro readings both front tires and rear tires

RED_DRAGON_85

dean, i have a question that i dont think you have answered yet.
why is it desireable to have a low roll center? or is it at all?
with a panhard bar rear suspension, the roll center is the intersection of the panhard bar and the differential.
however it seems that the idea would be to get the roll center close as possible to the CG height to reduce the roll moment and body roll...
the only thing i can figure is that you want the rear roll center to be close to the height of the front roll center to keep the rear outer tire loaded in turns
but i keep getting caught in a circle of what-if's and end up back where i started.

sorry if its a basic thing, but i cant seem to wrap my head around it.
also, does this mean that if the roll center were somehow located above the CG, the car would lean into turns?
again, seems impossible, and would only work in a vehicle with a very very low CG like a go-cart, but still...
i keep thinking that maybe the suspension would lean in to the turn but the centrifugal forces would still cause the car body to roll outwards essentially lifting the inside wheels completely off the ground
gah! im so confused.

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Norm Peterson

It takes less change in spring rate or bar size to achieve any given change in handling balance. In the extreme case where both roll centers are at the same height as the car's sprung mass CG it would be impossible to tweak that handling with (say) a sta-bar at either end, of any thickness. If there is no roll to start with, a solid "sway bar" that's 3" in diameter would accomplish nothing other than add a huge amount of weight to that end of the car.

In an independent suspension, a high roll center implies a large jacking force that tries to lift the CG (which then causes even larger jacking forces, since the RC also tends to rise). Not really a good thing, especially with grippy tires. Google "swing axles", "early Corvair" and "early VW Beetle". Or take my word for it that you don't want that happening with any independent suspension when you're driving it hard.


Close. The height of the PHB at the car centerline is closer still and good enough for most purposes. To be really fussy, the LCA geometry gets involved and can move the RC either up or down a fraction of an inch from there.


No. See above. You'd be stuck with whatever handling balance comes from the car's front to rear weight distribution and any tire size/wheel width/inflation pressure stagger. You'd be giving up what's possibly the best tuning method in your handling-tweak toolkit.


Load is going to transfer off the inside tires onto the outside ones no matter how much or how little the car rolls. Or even what direction it rolls in. It has to, because the inertia force (car mass times lateral acceleration from cornering) times the CG height are the only things that determines how much roll moment about the ground is happening. Roll rotation is only the visible chassis/suspension reaction to the lateral force, not the cause of that force.

What you're getting into is transient handling balance, before the roll has had time enough to fully develop. At the very beginning of cornering, there is no roll so all of whatever lateral load transfer is going on is going through the roll centers. This thread isn't developed far enough for that part of the discussion yet.


This has been done, experimentally, and I may be able to chase down a picture in the Millikens' book. There are some large disadvantages to doing this - I've seen pictures, and IIRC the tire cambers get really ugly. Keep in mind that lateral load transfer is almost completely independent of how much roll is present (I think the roll angle would have to physically move the CG a significant amount up/down/laterally for it matter at all).


One final thought - the geometric roll centers are NOT the points that the body actually rolls about. Try really hard to separate the forces that cause roll from the roll rotation itself.


Norm

RED_DRAGON_85

after some further research, the guys on the FSAE boards tend to all agree that the GEOMETRIC roll center should be at or within a few inches of the ground regardless of CG.
they also seem to have some feelings that the roll center, weather geometric or force based, is only a small part of tuning and should not be made a big deal of.


what i am referring to is the example of a front wheel drive car with a low front RC and the rear roll rate put way too high, causing the rear inner wheel to lift as much as 3" off the ground in some cases.
while this is required in a front drive car in order to get the *** end to rotate so you dont end up with massive understeer, the effect is opposite in a rear drive car, causing (what would seem) a lot of oversteer... is this correct?
my thinking (erroneous as it may be) is that a RWD handling oriented car will almost always have larger tires in back, so the cars roll axis should slope downward slightly to keep the rear in play, hopefully giving more grip.

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brutalform

OK lets knock it off, and stay on topic with this thread, or it will get locked. Questions will be asked in a sticky thread. Its ALMOST impossible to not have any questions being asked, but if they are we have to keep it cool with out any bashing or name calling. First there are two, then four, then before you know it, everyone is at every ones throats. A wealth of info here...lets keep it going.

Norm Peterson

Agreed. Tuning via roll center height tweaking has its place, but ignores changes that you might want to make in the longitudinal effects and ride frequencies. My understanding is the the RC heights are more important during the first couple hundred milliseconds and diminish is elastic effects take over as the roll develops.


You can think of "avoiding massive understeer" as being precisely the same effect as "causing a lot of oversteer", except that they start at different points on the scale from scary-oversteer-if-you-even-blink to understeer that's so heavy that you can hardly get the car to turn at all. In each case, the change is specifically an oversteer effect. IOW, in both cases you're moving toward the scary-oversteer-if-you-even-blink end of the scale without in either case necessarily getting all the way to scary-ville. What I'm getting at is that it's less a matter of where the handling balance actually ends up than it is that both cases are describing the same effect that precisely the same change causes, just in different words.


Not necessarily. That also depends on available power and vehicle weight distribution, and likely the front camber characteristics as well. Not to mention class rulesets in some cases.


The slight slope downward rear to front helps get the rear involved by causing its slip angle early-on to be relatively greater than the front slip angle. You then balance for steady-state cornering by making the front suspension have a significantly higher roll stiffness than the rear suspension does, which helps give you a progression that shifts the handling balance in the understeer direction (note that my mention of understeer here is only intended to indicate the direction that things are changing in, not that the heavy, plowing understeer that most folks think of when that word gets used is what you have to end up with).


Norm

RED_DRAGON_85

i think i understand most of what you are saying.
basically, for autox, set the car up so that with no sway bars, in steady state cornering, it will oversteer, then add bars to bring the balance closer to neutral?

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Vetruck

Many theories of thought, none of them wrong, each has its marraige of componants and settings..

I personally feel RC height to CG is very important. I evolve everything around a new roll center and where its migrating. Spring rrates will have a great effect on how much a nose dives, or a rear dives or jacks pertaining to leverage on 3rd links, Tqarms , front antidive properties, etc and the over all marrraige reaction of this in squating a car and inducing camber gain without body roll. There is so much that can be done, its all about driver feel and preference. I like soft spring technology now with advanced shocks and strut damping characteristics compared to what we had even just 20 years ago.

I was raised with heavy rate springs locking up the suspension and mucscling a car with power- then I started learning myself about suspensions and how they can actually work to your aid while actually artculating through travel and not locked up.

One thing I learned, The heavier the spring the more loss of mechanical grip

gotta go, sorry

mike_c

Excellent thread! I thought I had a relatively well sorted suspension...seems I have some work to do.

Norm Peterson

It would probably work out behaving that way.

The front bar on any front engine/RWD/stick axle car is so much stiffer than any rear bar for the same car that if you had a car that was decently balanced with them it would more than likely oversteer rather strongly if you removed them. Says the same thing just looking at it from the final arrangement and going backwards through the development to see where it would have been.

BTW, the above paragraph absolutely ignores the huge rear antiroll bars used by some in drag racing. Cliff's Notes for those things here is that roll is reduced but the handling balance up toward the cornering limit might get rather exciting (and not in a good way).


Dean - I agree that you really do have to start with roll center location. You have to start somewhere, and if nothing else, the sort of spring rates and bar sizes that are going to be reasonable choices depends in part on where the RC's are. Elastic element stiffnesses vs RC height is a big part of discussions that involve relocating rear roll centers (typically lowering them), whether that be due to completely swapping an existing rear suspension arrangement out for something different or simply lowering a PHB or adjusting an aftermarket Watts link.


Norm

radical82

I've been reading through this thread with considerable interest, some very useful information!!!

Though not having the technical expertise of some on this thread, I do have a bit of experience with suspensions and trying to make them work correctly. Roll center on these 3rd Gens seems to be a concern because of the lack of upper A-arm.... but with a bit of research I think I have discovered how to track and graph it properly.

My concern is this, going by the chart in post #50 it would seem that on the third gen's, the easy way to correct and establish a lower RC would be to lengthen the lower arm and put a bit more of a bend on the ball joint end of it to get the inner and outer pivot points equal.... or am I oversimplyfying this whole thing???

I read in one of Vetruck's posts where we used to compensate by stiffening springs!!! How true! and did we ever pay the penalty!!!!

Would you gentlemen consider 5" of overall travel on the front suspension to be adequate on a limited street use type 3rd gen??? Ride isn't that big of a concern, but handling is....I want to try the front coilovers and rack and pinion steering because of the huge weight reduction. Oh yeah, I don't mind a bit of fabrication to get the geometry correct, so how close can I get to "ideal geometry" with a bit of tweaking?????

Thanks for taking time for a newbie on the board!!!

__________________
Of course it's for sale!!! Everything is for sale!!!!

Camaro and other projects pictures can be seen at:

http://s534.photobucket.com/albums/e...1982%20Camaro/

Norm Peterson

Strut suspensions are relatively new to V8/front engine/stick axle cars.

It may help to imagine a fictitious upper arm that is connected to the strut at its top mount and is always oriented at 90° to the strut axis. This virtual arm will NOT be connected to the chassis anywhere, just imagine letting it float around and through anything that might really be there. Its length therefore does not matter, but if you choose something like 9" or 10" your sketch will at least look something like a SLA suspension. You'd probably use this little trick if you were going to set up a spreadsheet to do all the nasty detailed math for you.


RC height comes from the inclination of the lower arm (between the pivot centers, not necessarily along the arm's physical shape) and the fictitious arm that's at 90° to the strut axis. Where those two lines intersect is the front view instant center for that suspension, and lines drawn from the two front view IC's through their respective tire contact patches will define the roll center. Dean's attachment to post #8 shows this.

So altering the LCA slope, inclining the strut differently, or moving the LCA downward at both ends will all move the RC. Keep in mind that changes in strut inclination will directly affect the static camber setting. A longer LCA would affect the rate at which camber changes with suspension motion even if you don't change anything else.

I think that post #50 is more about illustrating that the moveable ends of suspension arms/links move in arcs rather than straight lines.


Norm

radical82

Thanks Norm! I guess the strut suspension intrigues me because of it's simplicity--though I must admit I'm having to relearn a lot of suspension geometry along the way!!!! I've studied Herb Adam's chassis books, his definition for determining RC's is fairly straightforward....saying to draw the 90 degree line you suggest, then an intersecting line denoting the lower arm attach points..... That part I can work out, then the re-education process begins on getting the caster, camber, bump steer, and anti-dive to all work in to the equation in an acceptable manner.... When I get a bit closer on my graphing, I'll post it up, but for now it's draw awhile, then go sit on the floor and move suspension pieces around, then sit and scratch my head!!!!!

Camber gain seems to come into play considerably on the strut front, In trying to compensate for this with the length of the lower arm, maybe I'm just confusing myself???? Not sure if my racing time is a help or a hinderance at this point, but I'm going to struggle through it and hopefully get a lot of insight from you and the others on the 3rd gen forum....

I do keep thinking there is a very easy solution that I'm overlooking--maybe time to just back away for awhile and work on the other end of the car?????

Vetruck

Graphs seem to work best to get points across so I will try and make another to show relation to front and rear roll centers and how they can sit 'static' (or stagnant) and then more importantly how they migrate 'dynamically' when the car is actually into roll and rotating around that axis.
Spring rate and roll center heights front AND rear play the major part in how chassis weight rolls. Roll couple (or as mentioned above the height of the cg from the roll center at each end is VERY important not to be too MUCH or too LITTLE. What I feel is major is keeping them dropping dyanmically at close to the same rate otherwise the roll axis dips and yaws upseting the flat plane of which the suspension mounts to, and thus the tire footprint.

When that plane moves, geometrically the contact patches get puled together and pushed apart on all four wheels in relation to eachother. Just like the graphs on level geometry of the suspension links (graph on #50)
in arch, The chassis suspension points also have arch if the roll axis yaws severly AND there is drastic motion teeter-tottering over it- Kinda of alot like high siding a motorcycle.

The first pic show a V8 car with roll centers adn a roll axis yaw like I had. A V8 car could not get away with it due to heavier CG and more frontward weight bias of the chassis (cg=green sq) my cg was slighly lower and more rearward towards 50/50. Most V8's are near 58/42 or above, I was 53/47 with the little 60*V6 and other mods. Note the YAW of the roll axis in purple dynamiclly. Blue dot is front RC, red dot is rear RC.

pic2 shows corrected RC's "AND" corrected geomerty with drop spindles keeping the migration more constant to static starting points. It also dynamically remains more constant to the cg in roll couple.

NOTE: both pics illustrate migration in a left hand corner, and please just assume lateral cg is centered with equal passenger weight for ease of sake.

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Vetruck

This is what I do in circle track with compression bank. I leverage the inside bank compression weight with a right side roll axis. Our cg is also 54% left weight and 51/49 front to rear and roll couple is low. We get articulation through bank compression squat of the chassis.

just an interesting tidbit to show how they can differ based on needs.

The orange dot in the second picture with connecting lines represents the longer chassis weight leverage in the LR. This has to lift under compression bank forces in order for the chassis to roll over onto the RF tire. This leverage helps keep weight onto the unloading inside rear tire.

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radical82

Thanks, Vetruck---I actually understand some of that.... So, when the time comes, RC's and CG plotted, components mocked up and the car sitting on the scales I can verify, tune, and tweak adjustments by simulating a side (weight) load on the car and the cross weights as registered on the scale will show the chassis loading????

Guess what I'm asking is, I'm not really much on all the math, plotting, and graphing involved---but when I get a car on the scales and can start playing with component placement and adjustment it all starts making a bit more sense to me.... Then again, I'm more then likely going to fall far short of "the ultimate" suspension, but what I do want is a very good handling front and rear suspension that will perform in a neutral manner.... I don't want to have to throttle steer and dirt track the car through every turn... I've found shocks and their valving to be both a tuning item for the suspension, and also seen them used to cover up some serious flaws in the design???? I would imagine a bit of comprimise is going to be necessary to get the car to perform right on "real world" roads with all their crowns, off-cambers, and the rest of the boo-boo's on a road....

I understand the RC's wheel weights, front to rear weight and transfer, CG's, and IC's---but admittedly most of the rest gets over my head...guess I'd better go back to studying......

Vetruck

This is exactly why I put high value on roll center heights, roll axis angle, and the height to the CG, NOT the height of roll center from the ground. I am glad you mentioned this Norm, It is a point I thought was being understood when I talked about keeping the roll centers in check because of straight line ride quality- I like your description when you say "longitudinal ride frequency".

Now to further the explanation why "I" personally put great emphasis and RC to cg height-

Lateral frequency and longitudinal frequency have to stay in ratio. Its why we have swaybars for aided increase in lateral roll without aided stiffness in longitudinal ride quality and grip. Stiff springs even deminish acceleration and braking grip.

If someone has roll centers too low from the cg they need way too high coil spring rates to resist roll, yet will suffer in straight line comfort. Ny simply adding larger and larger swaybars locks out independant suspension side to side.

keeping the roll axis inverted at a steep angle canters the rear into the air and will first overload an outside front contact patch and secondly unload an inside rear contact patch- You basically are going into a corner on a tripod- why have 4 tires then? 3 tires will not handle better than 4. As I stated before and will give a better example, it is best for all 4 tires to take as even weight of the car as possible at all times so each individual tire is making as much ability to grip the vehicle weight and move it wherever the driver is desiring.

if a car weighs 3600 lbs, its is best to have 900 lbs on each tire than 1200 lbs on 3 tires and 0 lbs on 1 tire---this is an exaggerated point...SOMETIMES- ever see a picture of a car lifting one wheel in a corner? Think that's cool looking? might be, but it is hurting his lateral grip.

Is ALL about the "roll axis' to "cg" FIRST in my book. From there? any variations will greatly depend on the suspenaion type and the provisions for adjustments, or lack of provisions seen in most factory street cars. That's why you buy an/or weld in anything adjustable you can get when buying parts.

Racecars, for the most part, are always built with everything adjustable. The only type of "racecars" I have ever seen lacking certain adjustments are generally space frame prototypes that have such a low cg to begin with that front upper control arm mount angle is a mute point with dive or antidive properties. The will engineer the control arm ears pivot tabs fix mounted to the aluminum spaceframes riveted massively. That generally is just trough years of evolution prototype racing chassis design by guys like Riley who are just unbelievably experienced and knowledgeable through the years of chassis building. They have their own desired chassis platform already tweaked through various evolutions.

Dean

ps- I am betting most of you have never heard the name Riley, but you will know his work when you see it. He builds these kind of platforms-

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RED_DRAGON_85

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Vetruck

Nope, I never said that. There may be some engineer somewhere that is a whiz in mathematics that might be able to do that, but not me. I simply do things by feel and by data acquisition (travel indicators, pyro readings, and just basically feeling or watching and listening to the car). From there, I see or feel where the chassis is cantering and I already kind of know aprox where the roll centers are and where they are aprox migrating to. I can assume how the chassis weight is transfering(through later force), leveraging(through roll axis yaw feel or visual, and pyro), and loading (through pyro, and/or psi build, and travel indicators)

Looking back to the entire point of starting this Ultimate 3rd gen thread- I merely stated I am giving the best geometry values that are unargueably things you can set to this optimum for your favor regardless of what you are then adding to the car componant wise. There are certain things that you set to the correct value, like scrub radius, A-arm stagnant angle for best camber gain- things like that. There is no "best camber setting" for all- camber is individual so I do not list stuff like that here. What I detailed here is a basic format and geometry to build on. You will have to take this "3rd gen 101 basics" format and and add your own componants. You could have eveything suspension wise the same as me (ride height, control arm angles, shock valving, spring rates, all rod end suspension, etc etc....yet, your car could weigh 3000 lbs with a 56/44 bias and a 56.3% left side weight and mine be 3100 lbs, 54/46 bias and a 52.8% left side weight...AND THEY WILL ROLL LATERALLY DIFFERENTLY even with the same stagnant roll axis.

Take for example the NASCAR supertruck I am envolved with. Every truck out there out of 41 trucks have to comply with rules. We all try and "basic 101" set up the chassis to the limit of the rules like for instance weight limit. They have to be 2700 lbs MINIMUM with driver over the scales in tech just prior to entering the race track. You can bet big bucks ALL teams are within 25 lbs of that. We are limited to track width up front of 70" and track sidtrh in the rear of 69". All of the 'good' teams take full advantage of leverage and get the LF outward that 1" more keeping the right side tires in parallel track. We run as much antidive on the upper right control arm. The left side is up for opinions- some teams run 'dive', some shim the contol arm up the 1" max we are limited too, others leave no shim and keep the arm inverted more for RC change based on spring rate choices. With all that said, The trucks all look for the most part 95% the identical same, and for the most part are. However, they all act so much differently on the track even though they all are restricted to the same weight bias and left side weight.

Now just think if they lifted any weight restrictions and think how that factor too would vary the factors---GREATLY.

When we are talking Ultimate 3rd gen here- we are discussiong using the best given built in qualities of the fixed GM 3rd gen f-body platform. We are not factoring what wieghts and options you have, what stereo boom box someone might have added in the rear, etc. Set these ultimate settings and go from there in fine tuning and fine tuning.

Its hard to give one person individual advice in a blanket chassis thread with so many vehicle options and weigh variances. Thiis thread is intended to give you knowledge of whats going on so you know what to look for or feel when you drive your car, then an understanding of how the chassis is leaning and how to diagnose where to go from there based on the axis it is moving on.

The #1 thing is keeping that A-arm angle in tack for two reasons, 1) not to drop the front RC intot he dirt in ratio to the rear RC ...OR also to the cg (center of gravity), and 2) keeping the lacking and camber curve at its best possible gain while reducing cg height. Even at that articulation, we still lack slightly in camber gain. The lower the car, the shorter the length of the strut to strut mount, the larger the increase in camber gain when A-arm geometry starts at the ultimate angle.

Vetruck

I realize what you are thinking but even trying to state it in a joke you quote is wrong.

Corner speed= LATERAL RESISTANCE of tire grip

3 tires "rolling" rather than 4 = less resistance= LONGITUDINAL RESISTANCE

and you are again cluttering up this post regardless off the crap Bruteform says people can ask questions here. This thread is so full of crap- I am finished adding anything more to this thread. To me, this is like a couple of high school punks writing in their text books.

I was actually in the direction of talking about lateral and longitudinal resistance too- I actually purposely do that with the NASCAR supertruck for straightaway speed. Evryones loss because of the two bigmouths, and the BS left on this page two by bruteform (Oh the banning memories are coming back with the mention of that name from the past. Is it a wonder why that BS towards me stayed and mine was erased towards them?)

radical82

Again, thanks for your input!!!! It certainly got me back to planning on my own car.... I realize there is no one absolute geometry or mathematics that will apply to all cars in any given handling situation...I guess that's why we all build them a bit different!!!! However, thatnks to the help on this thread I've determined some of my plan is good, some is not so good and it gave me a direction to go!!!!

As for Riley--- I think he built a car I crewed on "a few years back", an IMSA Mustang II owned by Charlie Kemp out of Jackson, Ms... I left them and came back to the frozen tundra to race sprint cars in '76....Often wish I would have stayed with Charlie, but then we all have 20/20 hindsight!!!

Anyway, thanks a lot for your input... One other project to get out of the way, then it's on to the Camaro's suspension and another car needing some chassis work for the winter... Thanks for making me think!!!!!

RED_DRAGON_85

you know dean, i am sorry but its called a sense of humor.
it was a joke and thats it. had nothing to do with actual (or make believe) physics, dynamics, ect... thats why they call it a joke


btw, just went and cleaned out my "bs" just for you!
happy?

Norm Peterson

Worse yet, once some tire lifts clear, whatever further lateral acceleration that might develop is transfered at the other end, without letting the airborne wheel back down. The "down" corner at the end with only one wheel down has nothing to transfer load to, so it just throws it to the other end.


Is or was half of "& Scott"?


Norm

Norm Peterson

Even the guys who can do that, still need to have test drivers get out there and actually drive the damn thing.

As far as I know, the engineering solution always gets tweaked. It may start out being closer than just throwing things together, and it will provide some idea how much you need to change "X" by in order to get "Y" change in the vehicle behavior, but it is not at all likely to be a final solution.

Test driving and a little "gut feel" is always going to count for something.


Norm