Cal Club Autocross Forums

To see if your front shocks are fairly centered in your upper A Arms. Like this:



Rather then off-set like this:



And let me know what your front alignment is ... stock, or ?

As you probably know, many Vette's aren't "perfectly" true. Henry's tires stick out a 1/4 inch further out on one side. In returning Karen's Z06 to near street settings I'm finding that things aren't lining up symmetrically. With all of the front eccentrics matching left to right, the same number of washers under the upper A Arm attachments, the slotted lower Shock mounting bar matching and matching shock pressures, I end up with the left side have less Caster then the right side ... thus the difference in shock position between the Upper A Arms. The car is bubble level even left to right.

One of the ways the factory evens things out is using no, or fewer or more washers behind those Upper A Arm attachment points. I don't know what the original set-up was from the factory for this particular Vette. I COULD add more Caster to the Left Side by adding washers behind the rear Upper A Arm attachment points. But I would actually prefer to reduce the Camber/Caster on the Right hand side ... but that would then de-center the right hand shock in relationship to the A Arm. Perhaps that's not important?

Cool ... I got a nice email from David Farmer: http://www.davidfarmerstuff.com/" onclick="window.open(this.href);return false;

... after he looked at this thread.

He said that since the shock's span from top to bottom is relatively long, a degree or two difference in angle between each side is not that important. C6's are looking like they are much more symmetrical while C5's are all over the place according to him. Even a Vette alignment specialist like himself says that it's virtually impossible to get Camber and Caster (especially Caster) really perfectly equal on each side, and to not worry about the resulting shocks position between the Upper A Arm.

Schenker is going to love that I'm going for this internet advice.

I like his common sense DIY Alignment Guide: http://www.davidfarmerstuff.com/align.pdf" onclick="window.open(this.href);return false;

Barco and I came up with the same method of checking Thrust: http://www.teamblewracing.com/forum/for ... p?TID=1276" onclick="window.open(this.href);return false;

While you're under there, you might want to check the lower a-arms...it is common for them to "walk" on their bushings (MY 2001-2003, mostly), which would also lead to the damper angles being different left/right, I believe.

Mako Koiwai wrote:...Schenker is going to love that I'm going for this internet advice.

Not at all: you're getting it from someone that has actual experience with what ever it is, as opposed to those that have opinions (i.e., interweb facts) w/o actually using/doing whatever the subject is...

Mako,

On my car the a-arms had moved forward significantly on the bushings, to the point where the lower(?) arms were metal/metal on the frame. That resulted in not being able to get anywhere near the max caster, which is in the 6.5-7 degree neighborhood. I couldn't even get 4 degrees. Because of the caster deficit I also could not get enough neg camber (1.3 vs (my) desired 2.0). After replacing both the upper and lower control arms all of the alignment numbers came together.

Bad deal for C5's: The control arm bushings are not replaceable with stock bushings - you have to get new control arms. Many $$$.

Steve Towers wrote:Mako,

On my car the a-arms had moved forward significantly on the bushings, to the point where the lower(?) arms were metal/metal on the frame. That resulted in not being able to get anywhere near the max caster, which is in the 6.5-7 degree neighborhood. I couldn't even get 4 degrees. Because of the caster deficit I also could not get enough neg camber (1.3 vs (my) desired 2.0). After replacing both the upper and lower control arms all of the alignment numbers came together.

Bad deal for C5's: The control arm bushings are not replaceable with stock bushings - you have to get new control arms. Many $$$.

I didn't read all of Mako's post, about his caster adjustment issues...Steve, you're right on target. The lower arms walk backwards under repeated braking force, the kingpin angle becomes more upright and there's no way to adjust the eccentrics enough to get correct caster.

For some reason, my Z06 never had this problem, even though it was an '02 (guess I didn't use the brakes hard enough lol), but I've worked on other cars that did have this issue. Best price for the LCA's used to be from GM Parts Direct (on the webz), but that was a few years ago, so things may have changed.

You would think either Gulstrand or Pfadt would have a fix for this.

by Arthur Grant on Sun Dec 26, 2010 1:19 pm
You would think either Gulstrand or Pfadt would have a fix for this

It can be solved to a large degree by using after market delrin type bushings, but they take you out of stock. The upside is you don't have to replace the a-arms.

There are probably a dozen poly/delrin/spherical bearing kits to fix this. None are especially "street friendly" or stock legal.

You said you are setting the car back near street alignment, do you mean to run it or just use it for street driving? What tires?

You can take the arms off and use a press to push the bushing back where it should be & then your alignment values will be available back in the factory ranges.

But if you are going to run the car & use sticky tires and brake HARD it'll move again. If you just commute/get groceries you'll probably be fine & keep your alignment.

The stock bushings are molded onto the pin & pressed into the CA. Not sold separate from the CA unfortunately.

street ... it's retired from AX this coming year

Mako Koiwai wrote:street ... it's retired from AX this coming year

If it were me, I would not worry about it, the little caster you won't have doesn't amount to much for street driving. Sometimes it'll even move back by itself, but don't count on it.

Or, pull the arm & press it back to where it should be, if you have the time it's not that hard to do.