My rear end is lopsided

[Pontiacgoodolddays]

Well, I’ve got an interesting situation. One side of my Firebird in the rear, (the passenger side) sits up 1.5” higher than the driver’s side in the rear. I just recently finished some upgrades wondering if they would correct the situation, but alas, it’s still lopsided. The rear leaf springs are new, they’re summit 2 inch drop rear leaf springs part number SUM-7081GM-2. The shocks are new, they’re Bilstein 24-001564. The bushings are all new, and when replacing them I noticed nothing out of the ordinary. The vehicle shows no unibody damage repair, the shackles sit at the same angle on both sides. I’ve looked at everything I can possibly think of, but it’s got me stumped. Before all the rear suspension work the rear end was 1.5” off, and after all the suspension work it’s still exactly 1.5” off. Am I the only one with this problem? Any ideas? Thanks in advance! - Tom

[FormTA]

It's just these cars.  Many of them have what is referred to as the "Detroit lean".  Both of my cars have it. One with original suspension and the other has all new PTFB suspension.

[Jack]

1.5" is on the high side, if it was half that I don't think most would notice it. Also I'm assuming that whomever installed the leaf springs knew what they were doing? i.e., lowering the car before tightening all bolts, etc.

[NOT A TA]

Detroit lean as we referred to it back in the 70's was usually only about 1/2" and occurred on a lot of F bodies. 1-1/2" is a lot, something else going on.

Have the sub frame bushings been replaced? Front springs? Problems with either of those can tilt the car

[Pontiacgoodolddays]

Thanks guys, subframe and and front suspension haven't been touched yet. Those will have to wait until this fall. I suppose it's not something I should lose sleep over! I think it's my OCD kicking in. Which should actually be CDO since that would be in alphabetical order. - Tom

[nas t eh]

What other measurements have you taken?

Distance between front spring perch and rear spring perch on both sides, how much arch in each spring,. If the front suspension has not been done yet, has one of the front springs collapsed or have a broken coil?

[81Blackbird]

Is the front driver side lower than the right?

[Wallington]

1.5" difference isn't OCD.

[FormTA]

Could be broken coil springs. One of the original springs on my car had an entire coil broken off and I didn't even no it until I removed it. A bad front coil spring will throw off the rear height also.

[Gene-73]

I had a similar rear lean when I purchased my 73, passenger side was 3/4" higher than the driver side. Installed brand new leaf springs, mostly to get the car to sit lower, and followed the instructions that came with them (had never done this job before). Instructions said to torque the front eye bolt in the mounting bracket before installing into the body, it even gave an angle measurement to set it at. Did that and afterwards the passenger side was still 3/4" higher than the driver side.

On advice of this forum I loosened the front eye bolt and rear shackle bolts, then retightened everything while fully loaded on the ground. Lean went away and both sides are now exactly the same.

[Pontiacgoodolddays]

Some great advice here! Thanks to everyone that piped in to the conversation. I'll just take it one step at a time, front coil inspection, loosen and retighten on the pavement, and so on. I'll report back on my findings, or lack thereof! - Tom

[firebirdparts]

It would be interesting to figure out if the car is twisted.  if it is, then it has to be lopsided somewhere and you'd prefer to think half the distortion on each end.  If the car is not twisted, then it should be leaning the same way in the front too.

I've never straightened one, but it wouldn't be impossible, and you could even fudge a little with the front end by tilting the subframe.  Probably not for the faint of heart, though.

Generally I think every bushing everywhere needs to be tightened with the suspension loaded.  That's a must.