I just put this Moser 9" in the car. I picked it up used from a member here on the board and took the car for a ride yesterday for the first time. I am getting a NASTY vibration whenever i stop accellerating. I am thinking maybe it could be pinion angle since I am running a stock torque arm, but figured i would post here and see if anybody knows anything else that may cause it. when I am accelerating It seems to feel fine, but once the foot comes off the pedal it feels like something broke!

 

No ideas, eh?

 

I am using the same rear. Now I am going off of memory, but might want to do a search here. If I remember right, some had a problem with pinion run-out due to the solid crush-sleve. They changed to a standard crush sleve and it went away. Others said they rotated their drive shafts 180 deg and it went away. Don't bother calling Moser, it wont help. I hope this gives you somewere to start.

Wingnut

 

thanks wingnut. I will try spinning the driveshaft and see if it nets anything. as for the crush sleeve, I hope that is not it. i really dont want to be trying to set up rears or even paying for it...lol.

 

I bet wingnut is right I had that problem once and it was very similar to what your describing. Do you have a steel shaft or alum. You've probly heard of that issue but you never know.

If you're using the stock tq arm you shouldn't have to worry about the pinion angle, but I suppose that depends on the cast pumpkin. If it is not cast with the same angle as the ten bolt then that could very well be part of your problem. Check the pinon angle by printing out a decent size protractor, poke a hole in the center and hang a washer from the hole with a nut or washer. Elevate the car with weight on rear tires and check the angle difference between the two. should be like to 2-3 deg. with teh pumpkin closer to horiz than the shaft.

If these don't help I don't what to tell you.

 

PaleHorse, a 9" does not have a cast pumpkin. The pinion angle gets changed with a 9" since the pinion is in a Different Location than with a GM rear (Not sure how much Difference.)

I spun the DS, no change. It is a Denny's Nitrous Ready. I actually ran the car up to 60mph on Jack stands and clibemd under there to feel the DS....It felt 'off' a little. I am fairly sure my problem lies in the Cast pinion.

The car is for sale right now due to Financial Probs. If it does not sell 'as is' very soon, I am taking it back to stock and will deal with the rear later on when I get another car to put it in.