hmmm..

what if there are 2 cars with same specs / mods / whatever you can think of (in a perfect world with no difference and no flaws) - except one car has lower spring rate in general and the other has a higher spring rate in general.

Same bodykit, same aero, same drag, same temperature, same weather, same tires (again, imagine this in a computer world where everything can be set the same). Both cars have "excellent" suspension geometry.

Does this mean that the car with the softer spring setting will generally be quicker?

Billy, I read what you wrote in the post before and maybe i should read it again if my question sounds repetitive.

Running stiffer rates just makes me think that aerodynamics should come into play to be generally quicker.. But then if i have that much downforce and say generally 1000lb springs, wouldn't the car have the best of both worlds if i had a lower spring stiffness to maybe like 700lb (low but not so low as to make the bumpsteer generally hardcore) and the downforce from the wing? (say, in the same track - same amount of turns, elevations etc)

 

"Excellent suspension geometry" is a vague statment. If you are stating that both cars (situation 1 and 2) do not have suspension geometry problems for their travel, you also must take into consideration roll centers, roll moments (given the same ride height, the softer sprung car will roll more).

Also, what is the difference between the 'stiff' and 'soft' spring rates? You have to consider their is almost always a limit of diminishing returns. The statement "softer spring rates typically generate more grip" dosn't mean that a 50lb spring will generate more grip on your car.

A lot of it will then lie in the dampers. Softer springs roll more, but more damping can make up for some of/improve the slower turn-in/response of a softer spring.

Their's a lot more to it than blanket statments, but if I get what you are trying to ask: yes, a softer spring will typically generate more grip given all the other parameters are in check unless the 'stiffer' of the two spring rates is already on the lower end of the spectrum of diminishing returns.

0.02


How does stiffer rates affect aerodynamics to 'come in quicker'?

Also, how does a 3,400lb-ish Pontiac GTO grand am GT racecar with a huge front splitter and rear wing run with 400lb (ballpark) spring rates?

I wish I had in-car footage from this weekend's 25 Hour of Thunderhill to show the difference of our softer-sprung E36 M3 (with a lot of aero) compared to a stiffer sprung car and attitudes of both in a corner. We had more grip.

 

No. The car with the stiffer springs will heat up the tires quicker and will probably be faster right out of the box but possibly will wear those tires more in the long run.

Assuming a glass smooth surface the stiffer car will have much less roll center and cg migration - this will typically lead to more grip and more consistent handling. Tire scrub will also be less on the stiffer car because of less dynamic alignment changes so this may in fact even out some of the advantage in tire wear that the softer car will have.

 

I forgot to address this about the tires in terms of working the tire/heating them up (for a time-attack event with minimal warmup laps (or corners) if the tires are not up to temp, they will generate less grip).

But in terms of the tires being up to temp, etc... stiffer springs generally reduce grip.

Their are tons of race teams/shops/etc... that have conflicting information/beliefs/etc... I drove a Acura TSX that had literally the opposite spring rates F/R as another TSX. Both TSXs turned similar lap times, both won races. Their are a bunch of different philosophies and ofthen the details about the limitations of the car (bumpsteer, roll centers, etc...) can off-set/overshadow and affect the car where you need to band-aid it with different setups.

This question/arguemnt can go on forever, and I am not here to argue my point and bench race. But I feel that a decent amount of information was given for some to get a better understanding than most of the threads out there.

yes their are always exceptions, and often the introcacies of the platform overshadow general statments. BUT - the people with KW's or softer spring rates should take away from this thread that if they lower their car too much, the bumpsteer issues and bottoming out issues will cause much worse handling. So if they must have that 'slammed' racecar look, they need stiffer rates, or they need to raise their car up to a better travel/ride height. Or they need to change some pick-up points and other aspects to offset the problems of lowering the S2K.

0.02

 

Define grip, if I'm running stiffer springs I don't need to run as much static toe and camber. Less camber means I have more braking grip. Less toe means better Ackerman geometry and more grip from the inside front tire.


Point being - there are a lot of generalities that are thrown around on the internet - there is a reason why top level racing is so expensive and why very little of that info trickles outside of the team/garage where those discoveries are made.

edit - Oh and don't forget about tires either. Street tires require different setups than race tires. Even race tire to race tire requires different alignment and springs.

 

This... I think Billy knows...

 

Now what if you have a strut-type front suspension that has no camber gain?

In this case, a stiffer spring/less roll COULD generate more grip -depending on the amount of static camber and how the tire is wearing.

This is also why a pyrometer is also a very important tool to determine what camber/toe setup is ideal for your tire size/compound/offset/spring rates/etc....


I agree, 99% of the information is misinformation.

A lot of what I stated was to help answer the questions/point out the problems that some of the people have with their SETUPS and not necessarily their dampers/spring rates.

 

Awesome post Bill.

But what if I want to go fast on the toogay? I can just slam my car, add the stiffest springs I can find and be teh winnar!?! Right?

 

[QUOTE=Ludedude,Dec 9 2008, 03:09 PM] Awesome post Bill.

But what if I want to go fast on the toogay? I can just slam my car, add the stiffest springs I can find and be teh winnar!?! Right?

 

but but keiichi tsuchiya