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For the guys that have done their own alignments, I'm curious how you did the rear. I have access to an alignment rack at the shop I still work at part time. What I'm wondering is what the best way to add and remove shims is with the car on the alignment rack. It's easiest to pull and place shims with the car off the ground and the wheel off for access. But that would mean taking the alignment head off and then having to reset it all after adjusting shims. That would be a lot of trial and error, which I'm fine with, but if there's a better way I'd rather that. Or, if that is the best way, is there a rule of thumb on how many shims to add or remove to get a certain amount of movement? (so I'm not shooting in the dark?).
I would take all the shims out, and do not lift the car. You want it settled. Tap the arm back and forth till you get it just toed in maybe 1/8" per side.
Slide shims in one side till its just packed. Then pack the other side of the arm till it's locked in place, then recheck.
I have found, when it's on the alignment rack. It's really not all that difficult to access the trailing arm shims. Going up from underneath is not at all difficult with the wheels on. And yes you want the car settled.
I would take all the shims out, and do not lift the car. You want it settled. Tap the arm back and forth till you get it just toed in maybe 1/8" per side.
Slide shims in one side till its just packed. Then pack the other side of the arm till it's locked in place, then recheck.
I actually just came across an old thread that said the same. I hadn't thought of starting from scratch, positioning it where I want, and then shimming to maintain the placement (vs shimming to try to move the arm). That sounds way easier, thanks for the info!
Last edited by 80vette21; May 18, 2020 at 08:11 AM.
I would say that FIRST, you need to evaluate how rusty the shims and/or the trailing arm retaining bolt is, because if there is a lot of rust present, getting the shims in/out, or getting the arm to slide back and forth on the bolt, could be a challenge, with the tires in place, and the car on the alignment rack.
If there is any amount of rust present, I'd suggest removing the wheels then all of the shims, first, and thoroughly cleaning out any "junk" that will prevent you from being able to freely move the trailing arm in or out, and preventing you from being able to freely install or remove shims. I'd also suggest that you purchase a set of stainless steel shims. Then put the shims back in the car, as they originally were, just so you can drive it to the shop, and then do a final alignment, on the rack
A quick tip. Put the thinnest shims in first and lightly hammer the last shim on each side using the thickest shim. It is difficult to hammer 1/16" shims in. Jerry
I would say that FIRST, you need to evaluate how rusty the shims and/or the trailing arm retaining bolt is, because if there is a lot of rust present, getting the shims in/out, or getting the arm to slide back and forth on the bolt, could be a challenge, with the tires in place, and the car on the alignment rack.
If there is any amount of rust present, I'd suggest removing the wheels then all of the shims, first, and thoroughly cleaning out any "junk" that will prevent you from being able to freely move the trailing arm in or out, and preventing you from being able to freely install or remove shims. I'd also suggest that you purchase a set of stainless steel shims. Then put the shims back in the car, as they originally were, just so you can drive it to the shop, and then do a final alignment, on the rack
Thanks. I did offset trailing arms and conversion to a 78 rear-end 5yrs ago, so everything is fresh. I steel have a new set of shims front and rear too
For the guys that have done their own alignments, I'm curious how you did the rear. I have access to an alignment rack at the shop I still work at part time. What I'm wondering is what the best way to add and remove shims is with the car on the alignment rack. It's easiest to pull and place shims with the car off the ground and the wheel off for access. But that would mean taking the alignment head off and then having to reset it all after adjusting shims. That would be a lot of trial and error, which I'm fine with, but if there's a better way I'd rather that. Or, if that is the best way, is there a rule of thumb on how many shims to add or remove to get a certain amount of movement? (so I'm not shooting in the dark?).
I appreciate any advice
slide 17 shows what manual says.. do not force one side first..
honestly..im not sure unless worn bushings.that is changes much ? maybe check first..
You can buy a inexpensive toe gage from Eastwood Company to check toe first before you change anything , it might be on the money and X2 on set camber first then toe
For the thrust angle, I'm assuming you want to align the front end first and then the rear so you can align the rear to the front? Is that the idea with the thrust angle?
For the thrust angle, I'm assuming you want to align the front end first and then the rear so you can align the rear to the front? Is that the idea with the thrust angle?
Thrust angle is measurement of the rear steering ( vs the front axle. So in a perfect world the front and rear axles should be perfectly center of the frame and if the left and right rear wheels have the same toe-in, would create 0 thrust angle.
I usually do the rear alignment first. Camber , thrust , then total toe. During the thrust adjustments I make the rear toe of each wheel equal to get 0 thrust and then adjust each rear wheel to get total toe.
Thrust angle is measurement of the rear steering ( vs the front axle. So in a perfect world the front and rear axles should be perfectly center of the frame and if the left and right rear wheels have the same toe-in, would create 0 thrust angle.
I usually do the rear alignment first. Camber , thrust , then total toe. During the thrust adjustments I make the rear toe of each wheel equal to get 0 thrust and then adjust each rear wheel to get total toe.
Quick question. Finally doing the alignment. My rear right toe was -0.56*, basically toed out a good amount. The left isn't bad, about 0.16* toe in. The right side wants all the shims on the outboard side, and nothing on the inside, and even then I still only get it down to -0.25* toe out. This seems to be the best I can get, the inner bushing is all the way against the frame, and the top of the TA is contacting the frame. My question is, is it ok to not have any shims on one side?
I have to correct part of that... Just grabbed a mirror, there's actually about half an inch on the inboard side to put shims. Looks like the reason I can't get more adjustment is the arm is hitting the frame. Would it be OK to notch the frame pocket? I may just leave it at close enough as I still plan on getting rid of the VBP arms and going with Vansteel arms and coilovers this winter.
Here's what I mean
Last edited by 80vette21; Jul 9, 2020 at 07:40 PM.
I guess I just don't really understand how thrust angle is any different than toe.... Other than that it's toe in relation to the front wheel toe.
its so your car tracks straight . You don’t want the left wheel toed IN 1/2 inch and the right wheel toed Out a 1/4 inch for a Total of 1/4 Toed In , your car car will go down the road sideways even though it is in spec . ...it’s better to have each wheel a 1/8th IN for a total toe of 1/4 In for a straight track ( layman terms) obviously an alignment rack is more accurate for thrust as it combines front and rear to come up with Thrust angle
Rear end alignment procedure
