I purchased a '85 2m4 car that already had a '94 Series I 3800 N/A motor swap. It felt a bit loose in the rear when driving around corners, but I thought it just needed alignment, as I replaced the rear RH tie-rod strut and end, so I knew it needed an alignment, as I just set it by sight.
I did also realize that both rear tires were not spaced equally in the rear wheel wells. The rear RH one seemed to be off-set. I thought an alignmernt would correct this issue.
When I brought it to Sears for suspension check and alignment, they were able to do the alignment, but said I should get fully adjustable ball joints in the front. That was it.

When I drove it home, the rear end was much looser, moving from side to side with both acceleration and deceleration.

The LH rear wheel measures 14-1/2" from the front of the rear LH wheel well to the center of the rear LH wheel. Compared to my other Fieros, this seems about normal.
The RH rear wheel measures 15-3/8' from the front of the rear RH wheel well to the center of the rear RH wheel. The RH rear wheel seems to be set back about 7/8".

I brought it back to Sears and they saw what I was talking about, but could not determine what the cause was. They said it did not appear to have any frame or cradle damamge, or cradle bushing issues.

Any ideas what to look for, that would cause the RH wheel to be set back like that?

Thanks for the help on this one!

Are the cradle bushings good?
Many people replace the stock rubber bushings with urethane or (even better, IMHO) aluminum. If the bushings are shot, the cradle can move around.
What about the right rear control arm bushings or their mounts?

It's also possible that the cradle got "tweaked", and/or the lower arm is bent backward. Also might(?) be a bent strut.
If you take a tape measure and measure from either left corner of the cradle to the right side control arm mounting points, you should have the same measurements as going from the the right corners to the left side control arm mounts.
Also measure from each rear lower ball joint to the corners (or better yet, opposite corners) of the cradle.
The cradle should be symmetrical, side-to-side, as far as suspension mounting points go. If it's not, your alignment will change as the suspension goes through its range of motion.

Edit - I'm betting that the control arm or cradle is bent. If something got sideswiped or curbed, the right wheel would have gotten pushed backwards by the motion of the car.
If you've got another Fiero around, compare measurements.

[This message has been edited by Raydar (edited 04-15-2012).]

Thank you for the help! I will check those measurements.

[This message has been edited by hdryder (edited 04-15-2012).]

Is there anything you can suggest I look for, that would show it might be a bad design of the 3800 engine swap, that would be causing this problem?

That would help me try to make the repair.

If it was worse after the alignment, I'd check for loose camber bolts and other fasteners in the suspension. I've experienced a shop leaving my camber bolts loose after an alignment. I was not pleased.

That doesn't speak to your other problem, but something like this is almost certainly not going to be limited to one component or one problem.

Do you have a right hand and left hand rear control arm or two left hand control arms?

quote Originally posted by hdryder: Is there anything you can suggest I look for, that would show it might be a bad design of the 3800 engine swap, that would be causing this problem? That would help me try to make the repair.

Not unless the suspension pickup points were changed, or the wrong control arm installed on the right side. (I didn't even think of that, obviously.)

Anything having to do with the install, that would have deformed the cradle, should have been obvious to the installer.
3800 installs are no longer "rocket science."

Great Ideas! I will check them out.

Thanks for the help!

quote Originally posted by olejoedad: Do you have a right hand and left hand rear control arm or two left hand control arms?

If I am not mistaken the control arms are marked L and R.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

You are correct, Dennis.

Update?

I wish I had some update info about the '85 rear drive-line situation, but I have been spending every chance a get on putting the top-end together on the '87 GT 5-speed, after tearing it down to replace the head gaskets. I hope to take a look at the '85 this weekend.

Can you tell me where the RH, LH markings are on the rear control arms? I have an '87 GT parts car up on blocks that I am stripping, and
can take the control arms off that if that is needed.

Thanks for the help!

I may be way off, but had the same symptoms and it turned out to be the tie-rod was worn out.

I have replaced the rear RH outer tie rod end, and inspected the inner tie rod end, which appeared not to be loose or worn at all.
I had Sears alignment look at the car two times, and they did not find any worn parts before they aligned it.

I will double check all tie rods just to make sure they are all good.

Thank you for any suggestions.

Could you have 2 left control arms?

I am hoping that is the case, as I have a set of good controls still mounted on an '87 GT parts car I am currently stripping of all good useable parts, before discarding the rusted space frame. I think that would be one of the best problem finds for me.

NM...missunderstood

[This message has been edited by JumpStart (edited 04-20-2012).]

My daughter wrecked her car a couple of weeks ago. It was obvious that the lower drivers side control arm and toe link were bent up pretty bad. I got the parts from a fellow forum member and also bought a new drivers side axle as the boot got torn up on hers when the control arm bent. When I was putting it together I noticed the same thing (drivers side tire was not centered in wheel well the same as passenger side). Turned out to be a bent wheel spindle right where the strut attaches. Was not very obvious sitting in front of it but if you stood back from it you could definetly see it with the naked eye. I took measurements of the passenger side to verify what I thought was wrong and purchased another spindle from that same forum member (thank god he had parted out a wrecked car lol) once I installed it everything just fell back together perfect. Another indicator to me was that the toe link seemed to be way off when I was trying to put it together before the new spindle.

quote Originally posted by donnie072003: Turned out to be a bent wheel spindle right where the strut attaches.

Good idea! Thanks Donnie!

I will check it out. Glad to hear you got your daughter's car working well again!

The easiest way to tell if the control arms are indeed a pair (instead of two of the same side) is to look at the front edge, there should be two small holes and the top edge between the holes has a V shaped indentation. The back edge of the arm does not have the holes or the indentation.

Simple illustration,,,,,,

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o o
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[This message has been edited by olejoedad (edited 04-21-2012).]

Don't you hate it when it deletes spaces...

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[This message has been edited by Dodgerunner (edited 04-22-2012).]

Thanks DR - stuff like that makes me

Finally got a chance to look at this problem again. I can now tell the RH Rear Control Arm is bent.

Might want to get your money back from Sears. If they aligned it with nearly an inch difference the wheel base then they didn’t pay very close attention to what they were doing. I did alignments for a few years and that should stand out like a sore thumb. With that said, are you sure it’s the rears and not the fronts (it would still show up in an alignment if it were the fronts)?