camaro diff installed (alignment issues)

[I'm Holdin']

Put my camaro diff in on Friday with a buddy whose a mechanic, it took us about 2.5 hours to do with no breaks, install was pretty straight forward. it rained all day so I didn't get to really play with it. Well today i dropped it off at Firestone to get an alignment, they fixed the front but could not get the rear to factory spec. attached is the printout. they referred me to the dealership or a specialty shop and suggested a new lower control arm may be needed. Has anybody else had this issue?

[GM Customer Service]

Hi I'm Holdin',

I am sorry to hear that you are experiencing an issue and may need to visit your local GM dealership. I would be happy to locate and set up an appointment to have your vehicle diagnosed. Please private message me if I can be of any assistance.


Jennifer T.
GM Customer Care

[Chewy]

What's the issue? What weren't they able to adjust?

[Eidolon]

I'm guessing it was for rear camber or toe. I had a tech shop say something similar on my car once back when it was stock. I dunno if it was because the eccentrics didn't have enough range or because the stock soft bushings don't have enough pressure to press against the tire and get the wheel into correct alignment despite.

When they adjust those eccentrics, they're adjusting the position of the wheel itself and causing it to move. But the tire is under load and doesn't want to move. So the sidewall will stretch to accommodate the wheel movement, but it will also put pressure back on the soft stock bushings. This could cause the adjustments they make to have less of an effect than anticipated. So they try to get 0.6 degrees more negative camber and only get, say, 0.4. Rolling the car back and forth to let the suspension/tire settle to the new position MIGHT help.

Someone with more knowledge than I about suspension and alignments should be able to comment on whether or not what I state above is actually an issue or not.

[I'm Holdin']

align.jpg

sorry bout the title, my 3yr old hit the keyboard.

the rear camber and toe is way off, firestone said they could'nt get it to adjust any further. i'm taking it to do the dealership in the morning. their best alignment guy was off today, so hopefully he can fix it. they mentioned shimming which im not familiar with but they said it would be more expensive if they have to go that route.

[Chewy]

Kevin, doesn't the aftermarket camber bolt kit eliminate this issue? Pedders has them, but you'd have to order them from someone like Crazy Paul in AU. Perhaps Whiteline or someone else has them too. I'm not sure. Eibach may have some too. I think they come in their "Pro Kit".

[THE Adam V]

When they adjust those eccentrics, they're adjusting the position of the wheel itself and causing it to move. But the tire is under load and doesn't want to move. So the sidewall will stretch to accommodate the wheel movement, but it will also put pressure back on the soft stock bushings. This could cause the adjustments they make to have less of an effect than anticipated.

Someone with more knowledge than I about suspension and alignments should be able to comment on whether or not what I state above is actually an issue or not.

Your logic is spot on. But actually you are wrong. alignment racks have pads on them that move so that you don't have to worry about this exact issue. Unless your shop is using an alignment machine from like 1982 then you are pretty much safe from this issie

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[Eidolon]

Your logic is spot on. But actually you are wrong. alignment racks have pads on them that move so that you don't have to worry about this exact issue. Unless your shop is using an alignment machine from like 1982 then you are pretty much safe from this issue

Good to know. So that pretty much narrows it down to...

Kevin, doesn't the aftermarket camber bolt kit eliminate this issue? Pedders has them, but you'd have to order them from someone like Crazy Paul in AU. Perhaps Whiteline or someone else has them too. I'm not sure. Eibach may have some too. I think they come in their "Pro Kit".

This. I never tried JUST the eccentrics from Pedders. A combination of Pedders eccentrics AND stiffer rear bushings (in aftermarket control arms) was what did it for me.

[Chewy]

I think Tony put in the Eibach eccentrics in mine and it has a mix of poly and rubber in back.

[I'm Holdin']

i'm at stock ride height, should the dealer be able to fix this or do i need the eibach alignment kit?