So i changed the rear suspension (adjustable lca,panhard,qa1 shocks(18 way adjustable) new springs(stock for now) and added a moser rear,along with bmr tourqe arm. Problem is the rear wants to roll back,i left the lca and panhard alone(had it on the car with the stock rear for about a month) .Is the ta causing the rear roll? Seems to be a bind in the rear of the car.

 

Moser 12-bolt or 9-inch? If 12-bolt, is it possible the torque arm bolts (2 on top/ 2 on bottom) have come loose? A known problem.

Where did you set the pinion angle?

What exactly do you mean by “roll back”? Not a term IĦm familiar with. Under what level of power delivery does this occur?

Did you install LCA relocation brackets? If so where did you set them? Are you experiencing any wheel hop on hard launch? Where did you set the shocks - compression/rebound?

 

moser 12,going to get a new pinion meter in the morning. my current says +2.. as far as roll,it feels like the rear rolls back and plants when you drive it,pulls hard for the little power ive got(somewhere around 370 whp) will be checking the entire rear in the morning, maybe something has come lose. This is just a street car,no track time.. My shocks are single adj set at 5 clicks.

 

Still not clear on the “roll”. But some thoughts on what might cause the sensation of “bind”:

Under load, the pinion wants to move (rotate) upward due to the rear wheel torque on the pavement. The torque arm stops it from moving (almost - a soft front bushing in the front torque arm mount allows some upward movement). You typically set the pinion angle at -1° to -2°, so any limited upward pinion movement results in a straight line from the pinion through the driveshaft or at least keeps the pinion shaft parallel to the trans output shaft.

There is also a change in the pinion angle if the body moves upwards or downwards (squat) relative to the ground. And, loose torque arm bolts on the rear axle assembly will allow excessive upward movement of the pinion. Way back, the Moser rear had a problem with those four individual bolts loosening up. Not sure if they solved that problem in later years. They should be checked regularly in any case.

Setting the shock compression to 5 may result in squat as the chassis drops. Then there's the front torque arm mount. Does yours use the stock mount on the trans tailshaft, or is it relocated to the chassis, replacing the sheet metal tunnel brace? If relocated, does it use a poly bushing or a spherical rod end?

Straightening the pinion/driveshaft pushes the front end dealer into the trans tailshaft housing. Squat can cause movement of the front end of the driveshaft to be forward, or backward, depending on the angle the lower control arms make with the ground. Stiffening up the shocks and using LCA relocation brackets can minimize squat, depending how low you set the axle end of the LCA. Will also eliminate wheel hop, if present.

Another thought - how closely did you set you new adjustable LCA's to the stock length? If you set them too short, the driveshaft moves forward, deeper into the trans. The stock driveshaft length provides about 1/2-inch of slider clearance in the trans. With higher HP torque levels, it's generally a good idea to provide closer to 1-inch clearance.

In all of this, “bind” can be created. The further the u-joints depart from the straight line, the more resistance there is to maintaining constant velocity. U-joints only work correctly within a limited departure from being in a straight line, and with the trans output shaft and the pinion shaft as close as possible to parallel. Misalignment causes “bind” of the U-joints.

You can also create problems if the front end of the driveshaft is moving forward, too deep into the tailshaft. It’s going to hit the support bearing. That might conceivably be interpreted as bind.

Then there's the issue of wheels hop where the wheels are briefly losing traction, regaining traction, and repeating the cycle. Could that possibly be what you feel?

Is the mods list in you signature complete? If so, 370 wHP (~425 flywheel HP) seems unusually high for a HOT cam. Did you stick with the 3.42 gear ratio in the 12-bolt? I ordered my 12-bolt with 3.73’s (car was originally M6) and was sorry I hadn’t gone with 4.10’s.