Hello all,
I'm pretty sure I'm going to be pulling my rear diff.......again. But I want to run this by you all to make sure this is what I think it is and maybe if it's something I can repair myself. I just got my whole car back together caused by a ginormous case of whileyeratititis that lasted 11 months. Now the entire car is back together and after my exhaust system was installed it was quiet enough to hear the whine for the first time. First to eliminate wasting time here's what I got:

All new spicer u-joints throughout.
Rebuilt trailing arms from V-Tech < 5000 miles ago.
Rebuilt rear diff with the Duntov Super Duty stub axles (not V-Tech)
Before installation I filled the diff with Mobil 1 75-90 LS gear oil.
After less than a 100 miles of whining, I drained the Mobil 1 and put in Lucas Oil 85/140 Plus and two bottles of posi dope.
No change at all. Same whine, same decibel level, same....everything.
Have driven the car spiritedly, but not abusively. No dumping the clutch or crazy burn outs.
The diff is behind a TKO500 and a 500hp small block 383.

So.....I have a whine that varies with rpm, but occurs under the slightest load from pushing the accelerator. It's pretty loud and can be heard over the stereo. I can make the whine start and stop by slightly pushing the accelerator and then letting my foot off. It occurs around 2000 rpm and continues to around 3000 rpm where it could still exist, but the engine noise eclipses it. Also, my car clunks when I sit in it or when I get out of it on the driver's side. I'm a little over 200 lbs. Additionally, with the car on level ground I can push down on the driver's side rear and make the rear go "clunk". I can not make the passenger side "clunk" at all by pushing the passenger side rear down. I've been over every inch of the rear driveline and no bolts are loose, no parts are cracked or broken, no fluid is leaking, no loose U-joints, nothing pops out at you. I'm praying that it's a driver's side wheel bearing, but in my experience wheel bearings make noise no matter if load is present or not. I've checked for play in both rear wheels while off the ground grabbing the tire at 12 and 6 and 3 and 9. Only the slightest movement at 12 and 6 and that is because the trailing arm moves with the tire. The bearings seem sound. What I don't know is since the whine varies with rpm is it a bearing I can replace on the diff? Something simple I can handle? Or do I need to get a pro to rebuild it like Gary or Mike?

 

Don't know what the clunk could be but the diff whine is typical of a bad set up on the rear gears. Only way to be sure is pull the diff and do a pattern check.
Mike

 

Thanks Mike,
If the diff was pulled and a pattern test was performed, can there be a re-adjustment or is the ring and pinion "broken-in" that way and will always whine no matter how good the new pattern looks?

 

I'm also with Mike, as sounds like the pinion angle's a bit out. Rear end work isn't for the amature wrench, and would take it back, tho who ever did the rebuild. If only driven this way for a 100 miles, the parts should be ok, but wouldn't drive it much more, before the set up is corrected.

 

subscribed.. my 71 has been doing the same exact thing for a long time.

 

Thanks to all have replied. Looks like I'll be pulling the rear end again.

Mike,
I tried to send you a PM, but your PM box is full.
Thanks,
-B

 

Hi B,
It's possible the gears can be reset if they haven't taken a pattern set yet. It really depends on the gear manufacturer. Cleaned out the pm box so go ahead and send it again.
Mike

 

Roger That
PM sent

 

Got a 96 LT4 that has recently developed a loud whining as loud as if not louder than the exhaust. The exhaust is already louder than most, it's a stainlees steel unit from Allens stainless steel exhaust just chambereed pipes and cats, not mufflers.could low or worn rear gear oil make this loud whine? Thanks, Chuck.