help identify noises in S50E30

[static]

looks like i found most of noises

tonight i changed diff fluid from some readline that whoever serviced my diff had presumably put, to a 75w140 amsoil gear oil with aldeco lsd additive.
Took it for a spin and get much less diff kind of oil (have yet to take it on highway)

also i found another "surprise". My driver side subframe bushing nut had probably 10 lb/ft of torque on it. Tried to torque it to spec, but it seems that either the stud or the nut are stripped.

Tomorrow will call my mechanic and yell at him

[1990m3]

the nut sits on a splined bolt. If the splines are stripped that nut will never tighten up, the bolt will just keep spinning. New bolts are about $5 or so and easy to replace. Pull the backseat and pop it up through the top, drop a new one in and it's done. The factory used a caulk/sealant on the top of that bolt after the splines were seated properly, it might be tough to push that bolt up through the hole if the sealant is still in tact.

Easy fix

[static]

thanks man, will try this soon

Alex

[Jason89i]

........Driven for a while and now i am 100% sure that all these nasty sounds are coming from the rear. Taking seats out made the sounds like 3x louder.

Again, it's humming/droney kind of noise only whe the engine is connected to the wheels (i e. accelerating or coasting in gear). When i completely let out throttle on highway, it gets really loud. Alex

i vote diff. ive had my share of them going out. exactly as you described.

i did have one rebuilt (input bearing / shaft bearings for 300) but within a year it started doing the same thing. if your going to rebuild the unit, do it right and spend the money. or, roll the dice and just get another.

cheers, jason

[static]

i vote diff. ive had my share of them going out. exactly as you described.

i did have one rebuilt (input bearing / shaft bearings for 300) but within a year it started doing the same thing. if your going to rebuild the unit, do it right and spend the money. or, roll the dice and just get another.

cheers, jason

well, i'll see how the amsoil 75w140 with additive will do for now, along with sound-deadening the rear end and tightening the loose subframe bolt (by the way, any guesses on whether or not it may be cause of majority of the noises?)
BTW, i have found absolutely no debris/shavings in the diff oil, guess it's good news

i know i am not solving the root of the problem, but at least it won't make it worse.

[dmitri]

im voting diff as well...ive had diffs go on several cars and they all started how you describe.