The Reverend

No, the issue of weight transfer is EXACTLY what you are addressing when you set up your shocks, springs, and sway bars.

As for the mugen spring rates - those would produce significant oversteer for a drift machine.

And as for not knowing what you're going to get when you make changes until you get them - that's pretty true. You want to always keep your original hardware in case it doesn't turn out like you wanted.

cdelena

Rev like I posted previously, if I listen to any number of experts you have it backwards. Stiffer in front will reduce oversteer.

We probably need to agree on which it is before going further with the discussion.. it is just confusing otherwise.

funcar

[QUOTE]Originally posted by krazik

Quote:

Do you have any idea what this practice is called so I see if I can find one in the SF Bay Area?

You can all (707) 584-3727 they are a (SCCA)trans-am team in the area. They should be able to help you or tell you someone closer. As stated elsewhere in this thread almost all raceshops have scales. They are at every SCCA National event, at least all the ones I have been to.

Luis

Semantics, Rev.

I did not say that the issue of weight transfer is not addressed by shocks, springs and antiroll bars. What I said is that these parts do not take part ('scuse the pun) in weight transfer. Weight transfer occurs only because you accelerate or decelerate as a result of throttle, brake or steering input or of road surface conditions.

Obviously, the way weight transfer affects the handling of the car, is indeed dependent on those parts.

The Reverend

I'm pretty sure on this one, cdelena. If you don't believe me, an easy way to prove it is to go get yourself a copy of gran tourismo or gran tourismo 2 and see for yourself. Or if you prefer, you can get a few sets of springs for your car and see. Or you can just read up on other web sites.

Higher spring rates give that end of the car more grip relative to the other end of the car. If you go high enough, this is reversed and you will get less grip because the springs are just WAY out of spec. But within normal rates, higher front rates=more oversteer.

Pepe

[QUOTE]Originally posted by The Reverend
[B]Higher spring rates give that end of the car more grip relative to the other end of the car.

Jason Saini

Cdelenda is right, Rev... I have been working with race teams for the past 10 years. Stiffer front = more understeer with all else equal. The only exception is a car that is too soft and has a crappy camber curve... and the S2000 has neither of these.

Stiffer front springs = More understeer
Softer front springs = More oversteer

Stiffer rear springs = More oversteer
Softer rear springs = More understeer

The Mugen rates of 570/370 would make the car more predictable and easier to drift - by increasing inherent understeer characteristics. You can't go by a video game here. They did a pretty good job with the physics on that game, but it's limited in the number of factors the Playstation can crunch. I have noticed that softening or stiffening tends to have the same effect. I have also noticed that stiffening tends to add grip, which is not true in real life.

Check out the physics of racing series... someone posted a link in one of the Car Talk threads. It describes some of these effects. Keep in mind, the handling of a car is a DYNAMIC event. There are forces that are affected by hundreds of variables. It is often hard to visualize *all* of these effects when thinking about suspension.

Cdelena is right though... you have it backwards, and that needed to be set straight. That being said, the Mugen seems to be on the right track as far as spring rates. I may get the chance to ride in one with the kit and I'll try to report. 570lb. springs would ride like crap, though!

The Reverend

First off, I just wanted to say that I am pleasantly surprised and quite impressed at the quality of this thread. This is exactly what I hoped for when I asked for a tech board.

This is indeed a complicated issue and there are different takes on the matter. This is why two race teams often will have cars set up no where near the way the other team is set up, but the two will still be equally matched on the track. You have gotten me to question myself and I will check with a friend who has been racing and building cars since before most of us were born to get his take on the matter. But until then, some things to consider... First off, this is somewhat counter-intuitive, but higher spring rates can lead to MORE body roll. I have found this to be the case with my HKS springs which have spring rates of 5.1 kg/mm in the front and 6.5 kg/mm in the rear (roughly 285 lb/ft front and 364 lb/ft rear). I believe a previous post stated the stock rates are 200 lb/ft front and 275 lb/ft rear. Since I installed the HKS springs, the car has more body roll than before, even though the springs are stiffer than the stock springs. If you think about this, it's not that hard to believe - while a stiffer spring will keep the outside wheel's suspension from compressing as much, it will force the inside wheel's suspension to expand more than with the softer springs. True, this is a many-variable problem and other factors play into this, but you may see (and I have seen) more body roll with stiffer springs. To this effect, you can think of the stiffer springs as working against the effects of your sway bar and would therefore cause that end to be the less likely end to loose grip first.

Another way to think about this is that your springs and shocks basically work against each other. The springs try to push the wheel against the ground and they try to react to imperfections in the ground. Theoretically, a higher spring rate should push the tire against the ground harder than a soft spring and handle better, but we know that is not always the case because of imperfections in the ground. The shocks try to slow the springs and keep the bounce down. We all agree that stiffer shocks on one end will make that end lose grip first. In a simple way, wouldn't you expect that if you increase the power of an opposing force to your shocks that you will lessen the effect of the shocks and the other end will slide first?

There is of course a pattern of reasoning that goes against this... If you have stiffer springs on, say the front... then you could argue that you are transfering weight from the front to the back and the back should now be more firmly planted on the ground. I am not arguing that this is not true and I'll look into the matter more to see if I can find a more reliable way to determine which forces win out. Of course, the flip side to this is that if you transfer that weight to the back, perhaps that will make the car act tail heavy and the back end will slide out first.


[Edited by The Reverend on 01-17-2001 at 01:15 PM]

Schatten

FYI - I put together a handling chart, its from an old Yokohama brochure. I kept one of these laminated in my wallet for reference. It eventually becomes second nature after a while.

https://www.s2ki.com/faqs/handling.php

Luis

Well, I don't. At least, not just like that.

Jason made the best remark of this thread when he said that when it comes to suspension, generalizations are dangerous. (although he then proceeded to make some dangerous generalizations himself ). See, a turn has two phases: a first, deceleration phase (starts when you start to turn) and an acceleration phase (starts when you start to undo the turn). Think in linear speed terms and you'll understand.

Let's call these the 0-90 phase and 90-180 phase for clarity. Stiffer front shocks will help with oversteering during the 0-90 phase part of the turn, but it will not be as effective if at all for the 90-180 phase of the curve.

What you would really need to tame oversteer would be 2-way adjustable shocks. You would dial in more front compression if your problem was oversteer in the 0-90 phase (on entry). And if your problem was oversteer in the 90-180 phase (on exit) then you'd actually reduce front rebound.

So, let's keep it as simple as possible.
But not simpler.

(copied w/o permission from Albert E.)