Rear axle placement

[Beamer]

Just picked up an 87 T and was under tha back today putting new variable rate springs and QC1 shocks. I noticed that the rear tire are sitting in different locations side to side. The driver side tire has way less clearance to the wheel well lip than the passenger. The car has boxed lower control arms and sway bar all intact. Any ideas if this is normal and can it be corrected?

Thanks,
Mike

 

[John Wilde]

Just picked up an 87 T and was under tha back today putting new variable rate springs and QC1 shocks. I noticed that the rear tire are sitting in different locations side to side. The driver side tire has way less clearance to the wheel well lip than the passenger. The car has boxed lower control arms and sway bar all intact. Any ideas if this is normal and can it be corrected?

Thanks,
Mike

Mike,

You could correct this with adjustable upper control arms.

 

[Beamer]

Mike,

You could correct this with adjustable upper control arms.

Thanks for the reply John,

Is this a common problem?

What is the cost of adjustable uppers?



I just got this car and am finding out a lot of stuff about it as I go, and of course, things that need to be done to make it better. I am going to look it over as I was reading about the different body bushings. I believe this car has had them replaced with poly. I saw this evening that the rear seat has a brace on it like the one that Kirban sells. Someone has done a lot to the car, but left a lot alone. It is sort of weird.



Mike

 

[John Wilde]

Thanks for the reply John,

Is this a common problem?

What is the cost of adjustable uppers?



I just got this car and am finding out a lot of stuff about it as I go, and of course, things that need to be done to make it better. I am going to look it over as I was reading about the different body bushings. I believe this car has had them replaced with poly. I saw this evening that the rear seat has a brace on it like the one that Kirban sells. Someone has done a lot to the car, but left a lot alone. It is sort of weird.



Mike

Mike,

It is pretty common.
My boy Ed just mentioned to me that he has this issue with his car.
Adjustable uppers and not that expensive and you have several options.


TRZ TRZ Motorsports - Performance Parts Manufacturing
Wolfe Wolfe Race Craft - Detail
BMR BMR Fabrication Inc.
Sphoon Spohn Performance, Inc.
Hotchkis Hotchkis Sport Suspension - 1978-1988
Currie Currie Enterprises Racing Rear End Categories
Chris Alston Chris Alston's Chassisworks, Inc.
HR Parts HRpartsNstuff "Your WWW performance parts supplier"
Metco Metco Motorsports Solutions - Adjustable Upper Control Arms

That is just naming a few.
You should be able to able to find a set between $200-$300.

Let me know if you have any other questions.

 

[Scott Atk]

John, How does that affect pinion angle and preload??

 

[jdpolzin]

Mike,

You could correct this with adjustable upper control arms.

John, this could be a body issue though! If so, the control arms wont fix that. My old GN was cricked from the factory. I ended up taking all of the body mounts loose and retightening the body back to the frame to correct it. Definately was fun! Not trying to contradict, just giving another opinion!

 

[John Wilde]

John, How does that affect pinion angle and preload??

Preload is set up with the after market sway bar.
Pinion angle is set with the uppers.
-2* is a good start for solid bushings.
-4 to 6* is good for bushings that deflect.

 

[John Wilde]

John, this could be a body issue though! If so, the control arms wont fix that. My old GN was cricked from the factory. I ended up taking all of the body mounts loose and retightening the body back to the frame to correct it. Definately was fun! Not trying to contradict, just giving another opinion!

That should be measured first! =)

 

[jdpolzin]

It really could even be a number of factors:

Control arm bushings gone bad
Body not mounted stragiht
Frame not straight from a wreck

But as John said, if the body measures straight to the frame, get a set of adjustable arms and the problm should be solved!

 

[Beamer]

If I drop a plumb line down from the wheel well molding and measure to the frame on both side and they are the same, then adjustable upper arms should do it? When under the car, it looks like body bushings have been replaced, and I am going to check if it has the additional sets not from the factory (5 and 7 I believe, I have a picture of the drawing showing where they are)

And do I need to get adjustable lowers also? I would prefer to use my boxed lowers to keep the cost down also.



Thanks,
Mike

 

[Lynn D. Brown]

Rear End centering

They are often off from the factory, or if somebody has F'ed with them. U can loosen the clamps and move the whole unit side to side.

 

[jdpolzin]

There is no need to buy adjustable lowers, utilize your boxed arms. How much less clearence are we talking on the one side compared to the other? Another thing to measure is the distance from the center of the front wheels back to the center of the rear wheels. If someone boxed the lower control arms, it is very possible the arms flexed when they welded them. This could be a factor as well. Just my 2 pennies!

 

[Beamer]

There is no need to buy adjustable lowers, utilize your boxed arms. How much less clearence are we talking on the one side compared to the other? Another thing to measure is the distance from the center of the front wheels back to the center of the rear wheels. If someone boxed the lower control arms, it is very possible the arms flexed when they welded them. This could be a factor as well. Just my 2 pennies!

OK,

Here is where I am at for the moment. The body is sitting off by 3/4" and the axle is only 1/8" off from the frame. I am not concerned about the rear now, just want to get the body aligned better for appearance as well. I saw there were bushings in the #5 spot that I observed on a drawing in this link http://www.turbobuick.com/forums/br...ng-suspension-stiffening-body-need-input.html


It appears to have new bushings from what I have seen. So, apparently it was not ensured to have been correct on the frame when tightened down.

Now for another funny thing about this car, the right rear of the car is sitting lower than the left. It had some modified MEGA-stiff springs in there. I just replaced them with a set of variable springs from Kirban and observed this problem. I looked at the springs that I took out a bit closer and saw that on spring is 9/16" taller than the other. What could cause such a problem? It looks like the upper control arms are not that old, but could be origonal. The GM sticker is in nice condition and they are unpainter with very light visible corrosion on them. The lower control bars have a sticker on them also, but are painted, and the rear sway bar looks like brand new. Someone has been under this car with a rattle can on the axle housing, but the under side of the car is very clean.

The biggest problem with this car is there is basically no history on it. There have been some nice mods to it without a doubt, but some things are up for question as to what has occured.


Thanks for all input people.

Mike

 

[jdpolzin]

Well, in my opinion, take all the body mounts loose and see if you can wiggle the body into place. There is a process when changing the mounts to follow and maybe they didnt do this. You should only need to loosen a few body mounts at a time in order to replace them. If someone had all of them loose, they very well could have tightened them with the body crooked. On the other hand, the factory wasnt all that particular on having the body straight when it was built, as many of us know.
As far as the springs go, if the car was rode pretty hard at the track, the right rear spring could have taken more abuse then the left. This could be the reason for one spring being taller than the other.Are the rubber perches in good shape? This could be another issue. If you need new ones, you can buy them from any local parts store! I replace mine everytime I buy a new car. I would start there and get the body bushing taken car of and see what happens!
If your rear end is only 1/8 off of the frame, you have no need to mess with the control arms!

 

[Beamer]

Thanks JD for the reply...

My plan of action for now is to replace the front shocks and then see how the car sits at each side front and back. I will then look to loosen the body mounts and shift the body over to where it belings - I think I need some good luck with that. I do not know if I should leave one side in the very front tight to use for aligning overall, then tighten one rear when it is centered and finalize by centering the front. I am sure it will not go easy.

There was/is no rubber inserts. I need to get them. Are there supposed be be some on top and bottom? I will need to look at the mounts closely to see if there may be something off there when under there.


I appreciate the help all !!!


Mike

 

[jdpolzin]

No problem. There should be rubber insulators on the upper perches that the rear springs sit on. Remember, this project of straightening the body is not going to be easy. You are going to have to take everything loose. Then adjust the body, then adjust the fenders and hood. It not easy at all but it is a good learning project. Get a good meter to match fender to door gaps! It actually kind of fun if you care to get into it!!