SpeedyGeek

iTrader: (2)

I have a 90 Formula and 87 Formula. Both have the Performance Suspension package. The 87 is worn out and the 90 suspension is in perfect shape. I have taken the shocks, springs, insulators, sway bar with link kits and the traction bars off of the 90. When I put the parts on the 87 will there be some kind of alignment that needs to be done? I know some cars can have front end AND rear end alignments but I heard you can't align a firebird rear end. Is that true? If so then do I just replace the parts and I'm done?

WIll36

iTrader: (12)

No you won't have to have your vehicle aligned if your only changing components in the rear suspension. On these vehicles there is no adjustment available from the factory.

slo91rs

should have it checked. the front toe is referenced from the rear thrust angle.

WIll36

iTrader: (12)

Yes thats true but these aren't IRS vehicles. There is nothing in the LCA's, torque arm, panhard bar or the shock and spring combo that would allow you to move the position of the rear axle relative to the chassis from the factory. All that is really necessary is to make sure that all the bushings are in good condition as well as the springs and shocks. Which if your replacing them hopefully your using new bushings and such. So yes you could have your alignment checked but most shops only check the front and will laugh at you if you insist on a four wheel alignment, because they can't do anything with the rear.

87tpi350,6spd

iTrader: (12)

Welllll I work in a shop and we don'tor are not able to do a 2 wheel alignment because you have to mount all four sensors to do any alighnment. and there for the front is set up off of the rear thrust angle no matter what even though you don't adjust the rear. That being said the only issue I could see you having is the wheel being off a little if it would be dog leging a little more or less with the new components. if that is the case just have it aligned.

WIll36

iTrader: (12)

Well I guess this is a case where certain members have different opinions on the best way to go about solving a problem. I've done 4 different rear axle swaps. Upgraded 2 of my vehicles to boxed LCAs and adjusted panhard bars, as well as help a friend of mine do the same mods. All we did was measure the distance from wheel rim to fender on each side to make sure with the adjustable panhard bars that the axle was centered. On my 88 it had been aligned a month before the LCA and panhard bar swap and I had it checked at the end of the summer cause the shop gave me a 3 month warantee on the alignment. I have the sheets from both and nothing shifted, and that was on one of the newer laser target alignment tables. So in my opinion which is by no means gospel unless you notice a change in the driving mannerisms of your vehicle after changing rear suspension components your throwing money out the window to have an alignment done.

87tpi350,6spd

iTrader: (12)

Well that is kinda what I was saying is the only thing that would be affected is the stearing wheel position. because it is set off of the thrust angle. The caster, camber and total toe should all stay the same I think. and the only adjustment would be the stearing wheel center. witch to do you have to adjust toe on both sides. So if you're wheel is straight and you know youre alighnment is good I don't think it would be nessasary.

WIll36

iTrader: (12)

Well from my understanding based on what I've read the rear wheels and thus the thrust angle are used as a reference point to set front end alignment, because barring an accident or other damage to the vehicle they shouldn't shift from the factor. That is as long as the bushing,shocks...don't wear excessively. So your front alignment will effectively not be changed by swapping rear suspension components. Think about it how could change LCAs and a panhard bar shift the position of your steering wheel relative to the rest of the front suspension.

SpeedyGeek

iTrader: (2)

Thanks guys. As it turns out you do not need to align anything when changing the rear suspension. So I swapped everything and it runs perfect.