85W140 / Gear whine troubleshooting
 

I recently installed an `02 rear end in my car. I was told it had 12k on it.

When I filled up the diff I used the Coastal 85w140 and posi additive from Autozone. Is this stuff bad news to use in a 10 bolt?

I am getting a bit of gear whine (compared to the old rear end), and I am wondering if this can be part of the cause.

Of course I am having other issue with the car that may also be culprut, the main one being that the new rear end installed seems to be offset about an inch the passengar side.

I'm thinking the old rearend was also offset and I didn't notice. Being that the 4th gen rearend is 3" wider, its a bit more pronounced.

I also installed a new LS1 driveshaft and new u-joints at the same time, but highly doubt any relation there.

The only other thing I can think of that may also be making the noise more noticable is that I went with Spohn LCAs with the poly bushings.

Any thoughts?

Is your car lowered? Might need an adjustable panhard rod to center the rearend

Will

Stock ride height on stock WS6 140k springs.

Could be the springs have sagged so much over the years. I know my car sits almost exactly the same as my friends does with the eibach prokit. My springs have 135K on them. Might be something worth looking into. I would do it regardless if I had the cash

Will

Since your car with sagging springs sits just like your friends car with lowering springs, do either of you have any kind of rear end noise possibly from the driveshaft being at an odd angle?

I am down to 1 of 4 things here... 1- The diff fluid I used is too thick and making the rear end noisy, 2- the Rear end is so misaligned that the driveshaft pinion angle is making the noise, 3- My tires suck *** and I just don't remember them making noise before, 4- This rear end I bought is junk.

Lets hope its something simple! :)

The noise seems most pronounced between 30-50mph... and if I play with the throttle I can hear a little more noise like almost a rattling from the rear end.

Maybe I am just nuts and the polly bushings made everything a little louder!

That jazz about the pinion angle being out of spec seems like a good thing to check. I know my 9 bolt makes a whining around 40mph, its nothing bad, but its noticeable to the person looking for something to pick on about his car, lol. Good luck man

Will

You are not getting whine b/c the diff fluid is too thick. If anythign that would help b/c it would be a thicker layer of protection between the metal to metal contact, which is where the whine would come from.

It could be that the pinion angle is messed up, but I really dont' think that would cause that big of an issue. What kind of life did that rear end have? If it was beat on at the track w/ slicks, then they is probably considerable wear on those teeth, and they will howl some. Question is this... Is it a bad whine, or just something that is annoying you? Gears whine. Its part of the game. If its something that is extremely loud, or accompanies w/ a vibration, then you may have a problem. Could it be that you are being overly cautious b/c you you did the install and don't want any problems???

I bought the rear end off of a guy with a 02 Trans Am. 12,000 miles on it. He swapped to a 12 bolt. I'm not sure how badly it was beat on, but it looked pretty clean inside.

The wine isn't bad, just annoys me. I have heard much louder rear ends than this one, and yes I am definatly being overly cautious. :)

Maybe I just need a louder exhaust! :)