What is this weird wobble from the rearend...

So I installed a New FRPP 3.73 unit and then I got this weird wobble sound (cant really be felt in the car, only heard) But it only does it when Im coasting. If I just barely touch the gas, it stops. And the rearend doesn't whine or make any other weird noises either.

Thinking it may be the u-joints, I replaced the driveshaft with a Dynotech shaft from dennis. Also wanted it to lessen the vibrations over 80mph. And the wobble is still there.

Then, just to eliminate all other things. I got the car aligned today because I knew it was off. And the wobble is still there. And it is for sure, coming from the back of the car. Dont know if its the rearend, or something else.

So anyone else have this problem or know what to do now?

check the 4 bolts that attatch the drive shaft to the diff. Mine come loose somtimes and makes a weird wobble/vibrating sound

just a thought

http://www.sccoa.com/forums/showthread.php?s=&threadid=28274

U might want to check ur crosspin in the rearend. It only made noise when there was no torque on the drive line.

Doug

So how do you replace this pin? And where is it? Or is it part of the case and I will have to replace the case?

And whats the best way to explain the noise yours was making?

So how do you replace this pin? And where is it? Or is it part of the case and I will have to replace the case?

And whats the best way to explain the noise yours was making?

U need to find out first if the noise is coming from the pumpkin itself. I put my car on a hoist and put it in 3rd gear and accelerated from idle speed to about 30mph. Only then did I know it was internal . The noise sounded kinda like a deep vibration or a clunking sound. If the noise is coming from ur pumpkin, pull the rear cover off and a dead give away is what ur fluid looks like. Mine had a bunch of metal shavings from the pin.
U can buy the pin and bolt from ford for about $20. The pin goes through the carrier assembly. In my case it was bad enough it egged out the carrier hole. So the pin and bolt is a tempary fix till i buy a new carrier assembly. Hope this isnt ur problem but if it is dont drive the car because ur rearend might blow out the back of the housing. Im sorry its so long winded..

Doug