Jetro

I'am curious what camber, caster and toe settings guys are using on the track. I've seen a few numbers in other posts but I am not sure if those are for the FD.

SleepR1

These are usually performance secrets not meant to be shared

sbaker25

Pettit racing has some guidelines if you want a starting place. There is no one answer. Ideally, the answer would be specific to a car setup on a specific track - even on a specific day for the pros.

The Pettit suggested settings are at:

www.pettitracing.com in the FAQ section under the link "What about handling?".

FYI, caster is not modifiable on this car (without major modification) but that shouldn't be an issue.

redrotorR1

Actually, caster is adjustable on the FD. Typically, the more camber and toe out that you dial in, the less available caster you have. I run -1.8 camber and - 1/8" toe (F), which only allows +5.5 degrees of caster on my FD.

But yes, depending on your racing preference, your alignment settings will vary slightly. Your toe will be more aggressive for auto-x and taper off for road racing. More camber = more grip; for me, it's purely a function of how fast I'm willing to go through tires. I think max allowable stock camber is -2.2 degrees on the FD. FWIW, I think Pettit's recommendations are a bit conservative.

My settings for auto-x:

TOE: -1/8" (F), 1/32" (R)
CAMBER: -1.8 degrees (all-around)
CASTER: +5.5 (the more, the better)

... too broke to road race.

sbaker25

Even if that were true (please see below) that is NOT what I would call adjustable caster.

Second, I think a little more explanation would be good here. Toe changes should not affect the inclination of the kingpin and should therefore not affect caster. Toe is changed with a rotation about the kingpin axis.

Negative camber should not reduce caster unless you have the opposite of anit-dive geometry in your control arms, posi-dive for lack of a better term. With anti-dive, the caster should increase with more negative camber. I don't know what the anti-dive characterstics of the FD suspension are, I've never measured this stuff on one.

Caster is not the more the better, although it's better to have too much than too little, IMO.

More camber does not equal more grip. More contact patch equals more grip and there is an ideal amount of camber to attain maximum contact patch when it's most needed. The idea amount is dependent on a multitude of factors.

Of course, the stop watch is the only thing that matters at the end of the day, so whatever works for you should be used, but I wanted to say to anyone else reading your alignment settings that toe out in the rear is not something I would recommend to anyone unless they know what they are doing, especially in a RWD car.

Anyway, these are my understandings. Please correct me if I'm wrong - particularly in the area of toe and camber affecting caster.

redrotorR1

I have toe in on the rears ... notice the negative sign on the front setting, and the lack of one on the rear setting. (A little note for anyone who goes into NTB or whatever for an alignment ... sometimes spelling things out for technicians confuses them.)

True, the end result of camber is creating a larger contact patch. I was actually trying to be terse in my comments. With the stock tire on an FD (225/50), you will eventually run into the region where too much camber is a bad thing (I doubt that you could with the stock camber plates though). Tire sizes and sidewall strength will affect your ability to increase negative camber. There are downsides; too much camber and you reduce the tire's efficiency. But tires will limit your ability to adjust camber well before you overshoot the limit of adjustability.

My caster proclamations are based off my experiences. I've gone through various different alignment settings and, in general, I've found that the available caster has reduced as I've become more aggressive with the toe and the camber. Perhaps it is a function of the spherical bushings that are used on the FD. The steel bushings will not allow the links to move as far as rubber bushings would; thereby, limiting the amount of play once stress has already been applied in one direction (obviously from the tow out setting). This is just hypothesizing though ... it's feasible I could be completely wrong. However, more caster is a good thing - especially with tail-happy cars like the RX-7. Positive caster promotes a greater "trailing" effect; that is, the rear wheels being forced to follow the line of the steering axis. Also, greater caster induces more negative camber on the outside tire and positive camber on the inside tire in hard cornering; which is effectively increasing your turn-in. But yes, it is possible to overdo it ... and once again, I will re-iterate that I highly doubt that you could with the stock settings.

Toe out in the rear is probably one of the worst things you could do in an FD. The car already likes to snap oversteer in a neutral alignment setting. You'd be in donut hell with toe out on the rears. Toe is a sacrifice that the driver must personally decide on. Increasing toe out is a personal preference ... sacrifice straightline stability for quicker turn-in response. A slight toe in on the rears will actually slow the generation of slip angles (bad for you drifter wannabes), and makes the car a little more predictable in cornering. But ultimately, your tires will be the difference.

I hope I have been thorough enough here. And feel free to correct me on any fallacies that I might be guilty of.

DamonB

Obviously you are reading a lot of books which is good, but your firsthand knowledge (at least on an FD) appears to be lacking. Castor is in fact adjustable because the lower control arm bolts are on eccentrics which allows the lower position of the kingpin to be moved about an arc. Those same bolts also allow the lower wishbone pivot to be moved in/out for camber settings; this relationship is why your castor and camber settings are related. Toe and castor however, are not related.

One of these days I am going to make some toe plates and see what kind of bump steer this thing has at different chassis heights and degrees of roll.

Redrotor, if you need toe out on the rear to make the car turn you are pushing like a ****. Fix the front first.

DamonB

I will show you mine if you show me yours You go first

redrotorR1

I dunno if we wanna see yours, Damon.

sbaker25

First, Redrotor, I read ' -' to mean toe in and '+' (or nothing) to mean toe out. I'm glad you have toe in on the rear .

Damon, I'm afraid to say, that the FD is one of the few cars that I have a lot of first hand experience with. I still don't call adjusting one of the lower control arm eccentric bolts castor adjustment. I honestly have only experience with castor adjustments on an older TransAm. In this case, you use shims to locate the upper arm rearward. I describe what the FD has as non-adjustable castor. I do not mean that to suggest that the castor is fixed and will not change with other alignment changes, I mean that it is not modifiable in isolation. I understand that, even the adjustment I described on the TransAm is not truly isolated, but I think you get my meaning.

Also, at no time did I say that camber adjustment would not affect castor, I said that it would not likely reduce castor unless the opposite of anti-dive exists in the geometry.

I should also say, particularly to RedRotor, if your experience shows a reduction in castor when reducing camber, that trumps my statements any day . That means that there really is the opposite of anti-dive in the geometry or I just don't know what the hell I'm talking about .

I suppose that it might make sense that you could adjust the front of the lower arm out to get your reduced camber and then toe the front in because, as Damon pointed out, there are separate eccentric adjustments.

I really don't have any practical experience here, so chime in Damon if that makes sense. If it does, it would seem to be a good thing, RedRotor because it would imply a castor gain in bump.