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View Full Version : 76 T/A - PTFB Comp Upper Control Arms w/ Tall BJs, Installed, now shimming questions



Henesian
07-12-2011, 01:24 PM
Hey, so I just installed my PTFB Comp Upper Control Arms with tall Balljoints(incase anyone was wondering, AFCO Low Friction race balljoint, AFC-20032-2LF).
The car feels completely freed up, and I can point the nose anywhere I want and the car will turn.

After I installed them, I put .250" of shimming all around, and went for a canyon road shakedown, since it's clear and hot outside, and the car handled fantastically. Also looks rather statically cambered, makes my 255/60/15s look small upfront.

I came home, and I changed it, so now I have
0.1875"(1/8 plus a 1/16, took out 2nd 1/8 and put in 1/16) in the front of the arms
0.500" (4 1/8's) in the rear of the arms.

Is there a clear way to translate shim thickness to number of degrees they add, or is it just complete guesswork?
What are your guys' experiences and thoughts on front end shimming?

JD'sTT55
07-12-2011, 01:53 PM
Normally the shim thickness or number of shims is meaningless. The only way to really find true suspension angles is to attach a measuring device to wheel or hub, center it on the wheel and measure camber in degrees and measure and turn wheel through steering axis to calculate caster. The shims only compensate for manufacturing differences between components and actual ride height. I believe someone posted what it takes to do it yourself on here somewhere otherwise you may need to find a reputable alignment shop that has alignment heads large enough for your wheels set it for you.

Henesian
07-12-2011, 02:11 PM
That completely saddens me.

opnwide
07-12-2011, 02:34 PM
There's a way to figure out differences by adding/subtracting shims, but its not simple. The problem is that the the caster also changes. Even if you added 1/8 to front and rear shims, the caster would change a little because of the angles of the arms, and also your aftermarket arms are set up differently from stock arms so if you found somebody that did the trigonometry on the factory setup then it wouldn't nec apply to your setup. Trial and error.
I would get a level and attach some blocks to it and guesstimate your camber. A good starting point is to have the top of rim about 1/4" away from a straight up level.

Henesian
07-12-2011, 04:25 PM
Alright. Im going to go outside and measure it. brb.

Damn. With only 1/16" shim on the drivers side, i'm out at 1.5", and with 3/8 on the passenger side, I'm barely at 1". What the hell. This bothers me.

BuzzKillian
07-12-2011, 06:58 PM
If you are going to check camber like this. You really need to be sure you are on level ground. Regardless of how it looks... the world is not flat:)

Henesian
07-12-2011, 07:43 PM
Yes, you are correct. I screwed up. Turns out the ground outside my house, is not level on one side, but level on the other. SOOO!!!! I pulled the car into the center of the garage, which is level(checked with a big super long level, not the car one.)
PS( The engine bay is also level, if that means anything)

With 1 1/16" in the front of both arms, and 3 1/8" shims in the rears of both arms,
it came out to around 5/8-3/4"(on both sides of car) instead of my heinously wrong numbers.
Which is still a crapload of camber. If you calculate it(dad's a laser physicist and instantly figured out how to calculate it), it came out to around -2.5 to -2.75 degrees. Which is insane. Knowing him, there's a 99.9% chance he's right.

Now this makes me think that we put them in wrong. We put them in so the offset arm( has the company label) is in the front, and the straight arm(no label) is in the rear. We think that's correct.
Then, the only two things I can think of is that
1) the stock lowers increase the camber, by the arms being as long as they are.
2) the cross shaft of the control arm is on the wrong side, because there is a larger indent on the other side of the cross shaft, than the one that is against the subframe mount.

Skip Fix
07-16-2011, 07:22 PM
48128The factory shop manuals had a whole page chart for what the shim change should be to change specs .