Most of all: Maximize front camber, especially if you have relatively soft springs. Why? Because the bump-camber curve doesn't come close to keeping up with the loss of outside front camber in roll, so you need a lot of static camber to stay negative in a hard turn.

Next, balance the car (as much as you can) with rear camber. My experience with 2.5* in the front is that about 1.5* in the rear was still probably too much. I kept adding rear roll stiffness to get the car to rotate and ended up with a car that pushed until it snap-spun. I will probably drop the rear to 1* or 1.25*.

Edit: I've now had the car for a year on 650/425 springs, Koni Sports, RM bars, and -2.50* of front camber and only about -0.75* of rear camber. I am liking it a lot. It will rotate on lift without snap-spinning and will do anything I ask other than zero-radius 180s. This could well be the best that could be hoped for on mass-produced, OTS shocks. It's loose enough to be fast without be terrifying at speed.

Front toe: you can help your turn-in by running some front toe-out. Causes some grief at other times (and greatly increases tire wear), but if turn-in is your key problem, try it.

Rear toe: slightly toed-in helps stability (especially if you trail-brake a lot), while slightly toed-out helps with mid-corner understeer. I just run zero. If you often face fast courses, I'd run a touch of toe-in; if you usually face very tight "Honda courses," then run some toe out, but keep in mind that this will make the car twitchy at speed and increases tire wear.

Caster: the nice thing about caster is that it provides additional camber when you need it (when turning) without adding any when you don't want it (when going straight ahead). The main down-side of adding caster is that it adds a jacking effect to the inside wheel. Some people will take the benefits and deal with the costs; others won't. The stronger argument against adding caster is that caster can onlly be changed if you install adjustable ball-joints (which have so many down-sides that I do not suggest this) or you install adjustable upper-arm pivots and twist them slightly and set them differently (which isn't as bad as funky ball-joints, but still not a great option). All in all, if you want more (or less) caster on a 2G, I'd be thinking about making a new upper A-arm.

With that said, I strongly urge anyone with a 96+ to flip the inboard bushing on the driver's-side compression arm. This will equalize the caster at about 4.5*, instead of having only 3* on the driver's side.

- Jtoby

This thread is not for questions, it's for numbers and first hand settings.

Please: Anyone with experience should post agreement or disagreement. I will adapt the first post in light in the feedback, such that we end up with a unified piece of advice. Please hold off on highly technical issues that might confuse novices. We can have those discussions in other threads.

Thanks.

- Jtoby

jtmcinder said:

Most of all: Maximize front camber, especially if you have relatively soft springs. ...Next, balance the car (as much as you can) with rear camber. ...
Front toe... Rear toe....:
Caster: the nice thing about caster is that it provides additional camber when you need it (when turning) ..... .With that said, I strongly urge anyone with a 96+ to flip the inboard bushing on the driver's-side compression arm. This will equalize the caster at about 4.5*, instead of having only 3* on the driver's side.

- Jtoby

Click to expand...

Caster can also be tweeked by using "subframe bolt slop" loosen the subframe bolts...tweek it forward (caster increase), rearward (caster decrease) or skew to help equalize cross-caster. Additionally, the UCA bushing inner-metals can be shortened, allowing shims to be placed at the bushing ends. The latter must be shimmed equal at front or rear of both bushings of the UCA. i.e. shims at the front of the bushings will increase caster...shims at the back of the bushings will decrease caster.

jtmcinder said:

Next, balance the car (as much as you can) with rear camber. My experience with 2.5* in the front is that about 1.5* in the rear was still probably too much. I kept adding rear roll stiffness to get the car to rotate and ended up with a car that pushed until it snap-spun. I will probably drop the rear to 1* or 1.25*.

Click to expand...

I believed the same until I installed Penske shocks, when all of that changed a bit. With my other single adjustable shocks before, rear tire temps would be quite low and it would take a lot to get them up. Also, only half of the thread was actually used (an inside one), while outside edge had no wear. Since utilizing these great shocks, overall grip went up and that made quite some change in the rear. With -2.0 degrees of the camber, car was using almost the full thread and temperatures where quite high and close to the front ones.

Having less then -1.5 degrees would be pretty bad and that would be the lowest amount I would recommend.


Fedja

Fedja -

I do not disagree and here is my understanding. Let's please discuss this for a while and then I will use this to alter the starting post.

When overall grip is low, either because the shocks are sub-optimal or because total roll resistance is too low, the rears suffer less than the fronts. Therefore, to get the car to turn, we do things to reduce rear grip, such as run rear spring rates that are too high, have custom rear anti-sway bars that are very thick made, or run rather low amounts of rear camber.

As we increase total grip, by getting good shocks or adding lots of total roll resistance, the front makes much bigger gains than the rear. Therefore, when we do start running cars with good grip, we need to undo some of the things that we have previous done to reduce rear grip. For example, you had to put some rear camber back in, while Dennis is running lowish rear springrates.

In summary, what I said is probably best thought of as limited to those running OTS shocks, low to moderate springrates, RM sway-bars, and 245s. Those with much better overall grip will not want to sacrifice rear grip in the way that I have suggested.

- Jtoby

jtmcinder said:

When overall grip is low, either because the shocks are sub-optimal or because total roll resistance is too low, the rears suffer less than the fronts. Therefore, to get the car to turn, we do things to reduce rear grip, such as run rear spring rates that are too high, have custom rear anti-sway bars that are very thick made, or run rather low amounts of rear camber.

Click to expand...

I don’t think I agree that rears suffer less then fronts in a situation you described above. Sure the limits of the car are much lower, but if driven correctly (no overdriving the front end, and overall being smooth), I believe that you will lose your rear end before the front one. Of course this gets much more complicated when we include different states (transition vs. steady state), but either way, I believe that you would loose your rear end sooner then front. Of course, it is so easy to overdrive the front, and that is when you gona loose that end. But, that would be still due to the bad driving, and not car balance.

jtmcinder said:

As we increase total grip, by getting good shocks or adding lots of total roll resistance, the front makes much bigger gains than the rear. Therefore, when we do start running cars with good grip, we need to undo some of the things that we have previous done to reduce rear grip. For example, you had to put some rear camber back in, while Dennis is running lowish rear springrates.

Click to expand...

Well, as I said up there, the most important thing is a car balance. In my case up there, I didn’t have whole tire thread used in the rear and that was the reason why I wanted to take some of the camber out. Once I got new shocks, almost the whole rear tire was used and there was no need for the camber change any more.

What I am trying to say is that camber should be adjusted so you don’t loose your outer edges due to lack of it, never even have them touched due to too much of it. Camber should not be used for the grip reduction in any way, since it is very complicated (close to impossible) to figure out the sweet spot. So, I would suggest to use the best possible camber for the particular driver and the tire choice and wear. And that would be the one that gives you the most grip and the tire life!

Fedja

I believe that you will lose your rear end before the front one.

Click to expand...

I agree completely. I can't remember the last time I ever experienced terminal understeer in a DSM... maybe 1998, when the car was still stock, and I was still prone to overdriving it.

So I agree that terminal understeer is driver-induced.

Camber should not be used for the grip reduction in any way

Click to expand...

Also agreed. Strongly.

The proper camber angle is all about keeping the tire happy. Too much or too little camber overstresses one part of the tire and underutilizes the other. Why carry the tire around if you aren't going to use it?

This is more true on wider tires than narrower ones.

I set camber by temperatures and by wear/buildup patterns.

Interestingly, I've never been able to correlate camber angle to either maximum grip or balance - but there is a HUGE effect on tire life (we're talking about race use, not street driving) With the camber angles optimized, tires last much longer.

DG

DG-FNR said:

I agree completely. I can't remember the last time I ever experienced terminal understeer in a DSM... maybe 1998, when the car was still stock, and I was still prone to overdriving it.

So I agree that terminal understeer is driver-induced.

Click to expand...

I'm still digesting the points made by Fedja in the hopes of creating a more widely-agreed-upon initial post, but I can respond to this idea right now.

For a long time, my car had 500/400 springs, RM swaybars, 2* of front camber and 1.5* of rear camber. This is not a freakish set-up; I would even go so far as to say that this isn't attypical of a daily-driven 2G that runs in ESP, even though running stock differentials makes it very hard to win in ESP. (The car was actually set up for STX, but 2Gs have since been [effectively] kicked out of that class.)

The car had terminal understeer. Gary Milligan drove the car and agreed. I don't like making appeals to authority, but in this case I will.

- Jtoby

Gary's usual ride weighs over 2000lbs less and has monster downforce. Gary's ability is well documented, but not everybody immediately adapts to whatever they jump into. It's entirely possible that Gary, used to a car whose limits are three to four times higher, was slightly misjudging how much speed he could carry through the corner and wound up inducing understeer.

It's also possible that he was provided an expectation that he unconsiously seeked to confirm. "Here Gary, try my car out. I think it has terminal understeer and I want confirmation" is different from "Here Gary, try my car and tell me what you think it is doing".

And if you want to play "appeal to authority" the two most successfull DSM drivers (in DSMs) ever have told you that terminal understeer is driver induced. What better appeal to authority could you want?

But.... if we take you at face value, and we assume that Gary had indeed adapted to the car and the car really was suffering terminal understeer, my first guess would be "dead tires" and my second guess would be "surface conditions, especially water, dust, or marbles".

DG

DG-FNR said:

But.... if we take you at face value, and we assume that Gary had indeed adapted to the car and the car really was suffering terminal understeer, my first guess would be "dead tires" and my second guess would be "surface conditions, especially water, dust, or marbles".

Click to expand...

Gary drove the car all day and is not known to be swayed by the opinions of others (especially when it's the opinion of a student), so I think it's safe to say that he was describing the car accurately.

I asked what I should do about it and he made no mention of my tires. I don't deny that they were not a fresh set of V710s and I agree with the implicit argument that total grip (like total speed) changes the balance, but I think he would have mentioned this.

Rather, I think that the problem with that set-up is very close to what you have suggested many times of late: the front tires were not happy and were not working well. 2* of camber is not enough when you have 500/400 springs and RM swaybars. And Konis with GC upper mounts don't help much, either. The grip being offered by the fronts was not enough to rotate 1800# of car. Meanwhile, the grip being offered by the rears was more than enough to rotate 1200#, so the car pushed at the limit.

One subtle point about this: the issues surrounding upper mounts, coaxial hats, springs at funky angles, and all that really only concern the front end. When you move from an OTS to a better set-up you will gain much more front grip than rear grip. (This is still my basic point in my exchange with Fedja.) So a car like mine is suffering at the front end, so it has terminal understeer. A car like yours or Fedja's or ACM's has made big jumps in front grip and behaves very differently.

- Jtoby