Colin Moseley

Hi
Can anybody give advise on setting please.
Late last year i aquired a 1989 camaro z28 iroc z converible.
I have a list of bits to do , buying four new tyres before i fit the front ones i need to check the caster and camber angles, i know that the camber is incorrect , but in the chiltons manuel it does not give any settings. If anybody does have any settings can you give me the toe in as well please.
Cheers:hail:

Trickster

Will this be sufficent for your needs.

iroc-si

I disagree with that. It is my understanding that the iroc had different settings. where camber was 1degree, and castor was 5deg one side, 5.5 the other. Remember to get it the right was round for the side of the road your on.

Si. :lala:

Trickster

All of these measurements are out of the 1989 GM service manual and there was no mention of different measurements between the various models of cars. On later years there may have been, However that is not documented in this manual. Here is some more info on it. What you are probably referring to is the rear tires.

Trickster

Some more

Trickster

and some more

iroc-si

try having a look at :

http://pageperso.aol.fr/sdgreyefdbv/...MENT+SPECS.htm

Si.

ps. Trickster: do you have any info on adjusting the castor angle. I know its done by moving the top of the strut mounting plate, but is there a method that preferred as to car on the ground, in the air... etc?

RMK

I'm putting a copy of this over to the suspension board. I believe Andy Fanshaw had 1 (or both) of his cars altered for driving on the wrong side of the road. Maybe he could chime in with some information. I know there are a couple of people who have talked about it in the past.

Trickster

Here you go Iroc-SI,

This is the rest of the section on the wheel alignment.

Trickster

and more

Trickster

and some more

Trickster

and still more. If anyone would like it, I have it in pdf format and can e-mail it to you.

iroc-si

Cheers Trickster! Thats great info. :yourock:

I've tried the rubber mallet to adjust the castor angle but it wouldn't budge. I think 20 years of underseal underneath it has got it fairly solidly attached. I'll try it again, and see if I can get this car going in a straight line....

Cheers again,

Si. :lala:

Vader

Caster is the "black art" of alignment angles, and while it doesn't affect wear when the car is traveling straight down the road, it can certainly affect tyre cornering wear, handling, and feedback.

On a car with front struts, like ours, caster that is too low (more negative) will tend to eliminate any negative outboard wheel camber on turns. This can cause unnecessary outer wear on both front and rear tyres because of the unequal weight transfer on hard cornering. Even if you are not pushing the car hard in corners, the tread wear may appear at least on the front end. It also can make the car feel loose in cornering, since the rear tyres are taking more of the side loading from excessive weight transfer from the front end. More negative caster does help (a little) on bump steer, but the gains there are wiped out by the lack of overall control in hard cornering on normal surfaces. I would suggest setting the caster as high as you can within the specified range, or just short of the point of losing high speed stability.

Camber should be 0° or less, even if you don't push the car hard through the corners. Again, on a front strut vehicle like ours, the lower swing arm arcs tend to turn the camber more positive on the outer wheels under cornering loads (just the opposite of dual swingarm suspensions with a shorter upper arm), so setting a little more negative can have a beneficial effect. It will also tend to put more weight inboard and provide a better roll centre of the entire body.

An important factor in all of this is ride height. Just like harder cornering, sagging springs will greatly affect the camber angle on strut equipped cars, so is important to consider when determining the camber you want. It may be advisable to weight the car as it would normally be during driving before adjusting any steering angles. If that means loading the fuel tank full and placing a 200 pound weight in the left front seat and a 100 or so in the right front, then try to convince your frame shop to do that. Sagging springs, or even new lowering springs can cause the swingarms to be positioned at a point in their arcs where all travel from compression is inward only, creating positive camber right away and causing great difficulty in achieving a satisfactory camber setting. If the lower end of the wheel turns inward as soon as the suspension is compressed, camber will not maintain at the set angle as desired for even a small part of the suspension travel.

That alone is a great reason to throw away the lowering springs and change to dropping spindles if you want to lower the vehicle (the ONLY correct way to do it on a strut suspension).

It is also extremely important to have true tiyes when aligning the steering. Worn tyres can cause unpredictable loading of the suspension and make correct adjustments almost impossible.

Vader

Wow! Did I get that all spelled properly?

Here's a suggestion (already "reversed" for Left-Side driving):

Street Use
Caster - R +4° / L +4.5° - Camber - R -.5° / L -.5° Toe 3/32"

Hard Street Use
Caster - R +5° / L +5.5° - Camber - R -1.0° / L -1.0° Toe 3/32"

Drag Racing
Caster - R +4° / L +4° - Camber - R -0° / L -0° Toe 1/32"

Road racing
Caster - R +6° / L +6° - Camber - R -1.75° / L -1.75° Toe 1/8" OUT Short Course - 1/16" IN Long Course