My saga keeps getting better and better....

Had issues with a local shop and a ring/pinion swap in my '88 IROC. They swapped the gears, but a whining came with them. So, I pulled it apart, re-set everything (backlash at 0.006", gear mesh perfectly centered), cleaned all the bearings, and replaced the crush sleeve that they failed to put in.

Everything is back together, and from what I can tell the rear is perfect. No noise that I can hear, at least not from the rear.

Now I'm hearing a distinctly loud metal-on-metal whirring/grinding noise coming from the tailshaft housing on the transmission. While driving, only occurs while coasting. When on the throttle, everything is perfectly fine.

At first I thought it was the gears, but I jacked the car up, put the trans in neutral, and had a friend rotate the tires slowly as I rolled around underneath. No noise from the rear. The whirring noise (even apparent at slow tire rotation) is coming from the tailshaft.

Is there anybody out there who has encountered such a problem? What did I do to cause this? The only thing I can imagine I did during this axle work was tightening the lugnuts on the tires while the car was in park and still elevated on jackstands, which I imagine put a bit of strain on the transmission. I didn't think it would hurt it that badly....

Transmission is a bone-stock 700-R4, with a B&M 2400 converter. I haven't pulled the tailshaft housing yet, as I'd like to know what to look for when I do.

Any input is much appreciated, you guys have helped me out greatly in the past.

 

Only two things I would know to look for would be the bushing that the trans yoke rides on that is in the tailshaft or a universal that grinded some of the needle bearings. If the bushing in the tailshaft is bad I would imagine you would see some marks on the yoke when you pull the driveshaft out.

 

Thanks for the input. I haven't had time to dig into the car yet, seeing as how I just finished finals for the semester. I'll let you guys know what I see when I do.

Anybody else have any ideas as to what is causing this? I want to know just how far I should pull my car apart and what I should be looking for.