So my rear end was all jacked from the previous owner's "mods".

97 SS, HARD shift kit, 3000 stall, 3.73 gears. Supposedly built tranny.

Rearend needed new bearing and gears. Got that done.

Gears have started making noise again. Increase with speed. Taking my foot off the gas and decelerating makes the noise go away.

When I get above 70, a vibration starts. Its what I would call a rotational vibration, as it gets worse and then better with a rythm. When its doing that, and I let off the gas just barely enough to be slowing down by just a bit, or just try to maintain speed barely, I feel and hear grinding from the rear.


sooooooo

Am I right in assuming the pinion needs to be tightenned, and that maybe my driveshaft is out of balance?

 

Maybe, get under there and see if it's loose. It shouldn't have any shake in it, obviously. And don't overlook tires as a possible source of vibration if you don't find anything else. If you suspect the driveshaft, you can reclock it and see if that helps or do the hose clamp trick on it and see if that helps the balance.

You may want to take off the cover and see how the gears look and check the backlash, maybe remove the driveshaft and see how it is to turn.

 

Well I was underneath the car today doing some other stuff, and checked the tranny mount. It has a poly transmission mount, with stock engine mounts. iirc, doesn't that work poorly together? I thought either both needed to be poly, and just the engine mounts........

 

A poly tranny mount with stock engine mounts will not cause any problems...... Mine has been that way for 13 years.

 

Okay, thanks.

 

So I have the car on jackstands in my driveway, and if I press up hard on the front end of the driveshaft at the tranny output, it will move up and down by maybe 2 mm.

Can that be my problem?

Secondly, when I run the driveshaft up to speed, do I want the wheels on or off the car?

Thanks!

edit: the panhard rod is bent towards the rear right near the bushing that is on the body side. Wow

 

so I called the dealership and they quoted me 350 to replace the output bushing. is that a lot?