M104-AMG

iTrader: (8)

I'm confused about the FD alignment specs on camber for FD's with 16-inch vs. 18-inch wheels as noted here for "long track":
https://www.rx7club.com/3rd-gen-archives-73/pettit-racing-alignment-specs-182680/
http://westpenn.rx-7.org/Files/FD_Align.html

The two sites above, both give different camber settings (front & rear) based-upon the wheel's diameter.

I can understand IF your tires' width are wider than stock, but not if you're just going from 16-inch to 18-inch wheels, and your overalll tire diameter is the same.

What's the reasoning for LESS camber (front & rear) with larger wheels ? Is it because of LESS sidewall flex in larger diameter wheels ?

I'm in pickle because my race-slicks are 275's on 18-inch wheels, but my race RAIN tires are 225's on 16-inch wheels.

Should I just "split the difference" in camber ?

Thanks,
:-) neil

Aeka GSR

iTrader: (4)

Your steering axis inclination contact point to the ground is no longer the same when going larger, which is married to camber. Changing camber should change the steering axis inclination landing point under the tire. You can see this on extreme camber situation where the tires scrub instead of pivot, you'll even see the front of the car walk when turning the wheel while the car is stationary.
The proper way to fix the problem is to change your wheel offset to put the landing point of the steering axis inclination back to the center of the contact patch of the tire.
But then again they may assume you already changed the offset to compensate, if that is the case I don't have an answer.

Edited to fix some mistakes.

M104-AMG

iTrader: (8)

Interesting.

So the 18-inch wheels I have are 18x10 with an offset of 50 from CCW wheels. I assume that this wheel has the proper offset for tire center contact patch. Is there a formula to determine the correct offset from the stock wheels ?

Hmm . . .

:-) neil

Aeka GSR

iTrader: (4)

Well personally I think it is a negligible amount. To see where the inclination lands you would have to draw a line from the upper ball joint pivot to the lower ball joint pivot point and continue that line to the ground. Not easy unless you get all the measurements and draw it on paper. But yeah, it is a small amount and I would not worry about it. I sure as hell don't

Fritz Flynn

iTrader: (263)

Neil that site is wacked

You'd tear up the leading edge on any those setups.

I'd recommend 1/16 toe and 5 caster and zero toe rear (6 caster is all the way forward I think and it's over kill and is not good for turn in).

Rear camber 1.5
Front 2

It won't change much based upon wheel size so don't sweat that. If the tire wheel combo height is different that will make a difference.

For some perspective Blackey is running on 315s or so is at around 3 camber. Typically the wider the tire the less camber needed so I think you'll find with a pyrometer/tire wear you'll end up needing more camber but it can vary of course based upon, spring, sways, chassis stiffness, tire, driver etc...

M104-AMG

iTrader: (8)

Thanks Fritz.

Also, I assume you mean NEGATIVE camber front (-2.0) & rear (-1.5), correct?

I was running -2 .2 (f) and -1.5 (r) previously, and the rear didn't want to rotate, and that with a 450 (f) and 350 (r) springs, Tri-Point front swaybar, and stock '93 rear sway bar, using the Hoosier Koni challenge slicks (275x30R18).

I just installed 600 (f) and 475 (r) springs.

Maybe I'll do -1.5 (f) and -1.0 (r) . . .

Rxmfn7

iTrader: (4)

Would a wheels offset change what you would want for alignment specs? If your wheels are a significantly lower offset than stock, lets say +25 for the fronts, would this have an effect on how you would want it aligned?

Fritz Flynn

iTrader: (263)

How was your tire wear?

I have the tri point bar set in the middle w/ a 93 rear bar. It pushes a bit auto crossing but I can put it any where I want it on the road course.

I haven't aligned my car in years and have moved the shocks all over the place so I have no idea where it's at right now but I'll post here when I reset it which should be soon.

6 caster will hurt your turn in causing too much rocking in the front w/ one side high and one low and the stiffer your front is to rear the more this will effect/cause your car to push. I'd also check your corners/cross weights. If this car is pushing drastically it is ABSOLUTELY not a camber problem when you have more front than rear.

Personally I REALLY like even springs on this car with alteast 700 front when running on good rubber. You could always try 700f 600r.

I have the Tein super Rs with 800 front and rear and run about the same rubber as you. 275 40 17 hoos.

Fritz Flynn

iTrader: (263)

Similar to tire width but you have to be careful because with traction comes lean so then you're back to adding camber.

As mentioned earlier I was shocked to hear how much camber blackey was running with is wide tire setup. If he's running that much camber it's there for a reason or he's getting the most out his tires which is all you can strive to accomplish.

finger lock

iTrader: (6)

M104-

I'd echo what Fritz has said so far. The set up on my track only FD for the last two seasons has been -2.25° camber front and rear with 5° caster, +1/16 toe front and 0 toe rear. I've run this with 285/30/18 R6 (A6) Hoosiers and 225/55/16 Goodyear street tires in the rain. I would recommend setting up your car for the dry and using the 16in rims in the rain.

To complete the setup I'm running 1100F and 1000R springs, 0.190in wall thickness speedway bar front and stock sway bar rear.

Best,

Guy