Driveline making some noises

[bwh13]

On my S52 swap with Getrag 250, it seems like there is more noise than I would expect. I have a new driveshaft, CSB, etc and there is a loud hissing noise that rises and falls depending on vehicle speed.

In addition the drivetrain makes some noises after backing up, but not fullly stopping and putting into 1st gear. It almost feels like the entire drivetrain is moving around some.

I have all new mounts under the engine and trans with a poly rear diff mount.

Any suggestions what these might be caused by?

[Wh33lhop]

Hissing noise? Did you notice this around the same time you installed the diff bushing? (also note that you should install matching rear subframe bushings if you install an aftermarket diff bushing)

Have you checked fluid levels?

[D-rock]

hmm.. sounds like a bad diff. Maybe...

[bwh13]

I have the rear poly subframe bushings as well.

Fluids are all good.

The diff has the OBX LSD I installed last year. The diff does whine a little, I just put in a thinner shim on the passenger side and the whine definitely has been reduced, but not eliminated. I wonder if it needs to use a different gear oil; I have Redline 75w90 GL5+ in it.

The hissing may be coming from the diff I just can't tell.

I'll probably throw in another diff and see what happens. What's another 2 hours under the car anyway :)

[D-rock]

Sounds like the diff! The oil wont fix that if its that serious only if its clunky.

[bwh13]

Yes I've come to the conclusion it probably is the diff making all the noise.

Oh well did the R&R last night to change that shim on the case. Guess I'll tackle replacing the whole thing tomorrow. Hope the other one I have is good...maybe I should put the original 3.73 back in there :)

[bwh13]

OK end of problem; installed the Z3 3.07 Torsen LSD equipped diff. Nice and quiet now. I actually like this gear better than the 3.25. Should make highway cruising much more pleasant...