I recently put a new Moser 9" in my 87 firebird and I thought everything bolted up fine until I went to tighten things up (front and rear up on jack stands). I went to jack up the rear end and get the suspension in the compressed position so I could tighten all the bolts. This is when I found that the rear end of the car came off the jack stands before the suspension fully compresses and the car has about 5" of wheel well clearance? Dont get me wrong the suspension moves just not as much as it should.

I have all after market parts:
hotckis control arms
hotckis panhard bar
hotckis sway bar
hotckis rear springs
spohn cross member mounted torque arm
spohn sway bar instalation kit for 3" axle tubes
spohn lower control arm relocation brackets
kyb agx shocks

The car sat fine with the old GM 10 bolt rear end and this set up. Due to the new 9" it seems that the torque arm is more forward in the car on the shackel spohn uses on the tranny crossmember but that does not effect anything.

I have unbolted one thing at a time and tried jacking up the rear end to try to find if a part is binding:
torque arm
shocks
panhard bar
put control arms back to the original location

With each part unbolted one at a time I had the same result, car sitting like a truck. The only time the suspension fully compressed was when I took the springs out? I also tries two different sets of springs hotchkis and OEM, both had the same result. Also when I put the car back on the ground the car sat normal?? At this time I thought that may be I was caused by not having a sway bar hooked up yet, allowing the rear to not equaly raise on each side causing some sort of bind. But I just installed spohns kit to put my sway bar on the 9" and still the same result?

What do you guys think? Is there something wrong here? I know that my suspension always compressed with a jack on the last rear end. Any ideas, I am so confussed.

 

I forgot one thing. I also checked to make sure that the drive shaft was not to long and bottoming out on the output shaft but what I found is also confussing. When the suspension is hanging the drive shaft is deepest into the tranny. When I jack up the rear end the drive shaft pulls away from the tranny. Is this correct or is this part of my problem?

 

where is the pinion angle? is it set way off and causing things to bind?

 

pinion angle is set at -1

 

My car sat higher in the rear after putting my Moser 9" in too. Later found out the it might be from the larger axle tubes. It was suggested to remove the spring isolators and to slide rubber hose over upper coil to lower the vehicle.

 

Its not that my car now sits an inch or so high, its about 4-5".

Let me ask you guys this if you have your car up on jack stands, on the frame with the rear end hanging and you jack up the rear end does it compress to the normal ride height where it would sit on the ground?

When I jack mine up it only compresses half way or so, and it looks like a truck with 5" of wheel gap. But once I lower the rear of the car on the ground and then jack the front up to get the front jack stands out the rear will settle to normal ride height? I think that something is binding but I not sure what.

Any ideas?

 

you must not have the springs seated properly or something is causing it to bind, whether it's the driveshaft, suspension tightened before the weight of the car was on the rear, etc. Mine raised up 2" probably from the moser swap. I removed the rubber isolators and did the heater hose swap, later I cut another 1/2 coil out of the rear coils to lower the chassis even more, but it certainly wasn't 5".