Are the front shims on the upper control arms used both to adjust camber and caster? I can figure out how they would adjust the camber on the wheel. Not sure how caster would adjust? Shims would have to be equal to adjust camber but mine are set up unevenly. More shims in rear.

 

Adding shims to the rear only increases positive caster. Adding shims to the rear only also increases negative camber at about half the rate of adding the same thickness shims both front and rear.

 

Hi V,
I think this diagram does a pretty good job of showing how the shims affect caster/camber as Neil describes.
Regards,
Alan

Note this is the left side a-arm and where the front of the car is.

 

Confuse on how camber and caster is set together. I know how to set camber but how do I measure caster?

 

Caster is usually measured by comparing camber angles at different steering angles. On a home alignment, it's difficult to get an accurate caster measurement. But as a general rule of thumb, the more positive caster the better. What I try to do is get the most caster possible while putting my camber where I want it.

As an example, you can set your camber using equal shims front and rear. Then, you can move shims from the front to the rear bolt to increase caster (but maintain the same camber angle). You can run a fairly large shim difference front to rear. Then, set your toe last.

 

Ok, Got it. I was thinking is that if I have different amount of front and rear shims for caster setting that would offset the camber setting. Thanks.

 

If you just remove shims from the front it will reduce camber, but if you remove and the front shim and put that same shim on the back, your camber will remain the same.

 

So if I am understanding correctly that in turn will maintain positive caster?

 

Add a shim to the rear only = increase positive caster, increase negative camber

Take a front shim and move that shim to the rear = increase positive caster, maintain existing negative camber

Add same size shim to both front and rear = maintain existing caster, increase negative camber

 

Ok. I'll print these instructions out and work on this during the week. I believe there is 1 shim in front of driver side and 2 shims on front pass side. I saw pack of shims in the help section of the local auto zone store I will get. Thanks Neil!

 

Something you guys need to consider about adding caster. Yes, 3-6 degrees of positive caster is nice in a power steering car for forward stability and self centering. But there is a problem. Adding more than stock positive caster drops the steering arm, and adds bump steer which is bad. If you put more than 300 HP under the hood and let into it, the front toes out and gets it squirrelly.

The only thing worse than bump steer is rear end bump steer... Oh.. yea.. the C3 trailing arm IRS has that too.

My suggesting is unless you can get a bump steer kit, keep the castor below 2 deg pos

 

Set front camber and toe. Left front caster the way it was set up. Did same to rear camber and toe. Car drives straight as an arrow. Maybe in spring have shop check it. But am pleased with results.

 

 

My 2cents. Driving straight as a arrow usually means both the left and right side are equal in settings, this doesn't mean you will get max tread life. There are many settings that will make the car drive straight. Until you look at tread life/ or actual alignment readings you will never really know. Now if you only drive 1000 miles a year it doesn't matter since tire age out weights tread life.

 

[QUOTE=cagotzmann;1594060952Now if you only drive 1000 miles a year it doesn't matter since tire age out weights tread life.[/QUOTE]

Bringing car in for align as soon as spring breaks. But it's good enough to get it there.

 

Hi V,
You don't happen to have a date for spring breaking do you?
Regards,
Alan

 

LINY just got 12+" of wet snow dumped on us. No time soon Alan

 

Great diagram Alan,
What caster, camber setting is everyone using? Is it best to deviate from factory recommended settings?
What is the best setting for getting the car to go straight without wandering?
What settings do you recommend for the rear?
Tire wear is not a issue as I don't ddrive the car a lot.
Thanks,
Jim
Thanks, Jim

 

I'm currently facing these simliar questions. however, if I should be starting a new thread, please advice or if a modarator can just move the thread I'd appreciate it.

I just dropped my car at a (trusted) shop. I rebuilt the enter rear end (trailing arms from zip, new 9-leaf spring, all new poly bushings. Front has new poly bushings in upper & lower control arms. New Borgeson box with steering box/frame support from RideTech. All new tie rods.

Here's where I deviate a little more from stock: the cross shafts on the upper control arms are slotted (I put them on a mill) 1/4 inch towards the rear (this is based on past threads by Norvalwilhelm and Gkull) with the intent of gaining more castor than stock settings.

I gave the shop the catalog from Vette Brakes and Parts where towards the back they have alignment specs for the offset cross shafts. The only instructions i game them were:

Why? There were a number of threads talking about how the factory specs were built for bias ply tires, not the wider radials we're using. Also , people shared feedback about the Borgeson box being 'squirrlely' on the highway. I'd like to avoid that.

I don't have test results yet, meaning I didn't drive it nor will i for a few months. It's an experiment-in-progress. I also have 400+ hp & torque. So we'll see what happens. If those who have the experience can share feedback, I'd be grateful.

 

I just aligned my car at home. I also have the Borgeson box and Ridetech frame brace. With the stock control arms (read: very little caster) it was squirrelly as hell. I am running 275-35-18 Hoosier R7s up front and aligned to full track settings. With 1.5 degrees negative camber, 1/16 toe out, and as much caster as I could get with the stock arms, it now feels great. It's still almost too 'responsive' on the steering. I may go to zero toe or slight toe in to help with this.