lsd problems

Fri Jan 07, 2011 3:58 pm

got my 3.9 lsd fitted to my e30 lastnight and went and picked it up today.
it drives really nice now compared to it having a welded diff but it makes a really loud whining noise from low revs and gets more high pitched the faster i go. anyone know what could cause this?
also my speedo has stopped working too. does the speedo get its reading from the diff?

Fri Jan 07, 2011 4:10 pm

Has it got oil in it?

Speedo gets reading from the diff. Odds are the wires in the sleeve leading upto the plug on the back of the diff have become brittle & snapped inside, need to replace a good 18 inches of wire to probably sort this. The connector is the same as headlight connecors so if you need to rape a replacement plug & wire from a breaker, look there.

Fri Jan 07, 2011 4:21 pm

ive got the old welded diff so could i use the sensor out of that? it worked fine before lastnight.
as for the diff i will check the oil tommorrow. i asked my mate who fitted it to top the oil up and am now hoping he forgot haha. the noise goes away if am not on the accelerator

Fri Jan 07, 2011 4:29 pm

What Oil did your "Mate" put in?

LSD Oil is different from normal diff oil

Fri Jan 07, 2011 4:37 pm

he had some 75/90 in his garage. sounds like theres none in though. never heard a diff whine as much as this but probs sounds a bit louder as ive stripped the interior and carpet out.
the welded diff didnt make noise just made the car crap on the road.

Fri Jan 07, 2011 5:32 pm

Don't drive it if there's chuff all oil in it or you will be weighing the diff in.

I believe the BMW LSD with the clutch type LSD requires some form of Castrol SF/XJ fluid 75/90 or something like that - speak with someone like Opie Oils and they'll know what shizzle you need.

Can you actually vouch for the diff being quiet before it was fitted?

Fri Jan 07, 2011 6:01 pm

That will be the pinion bearing f4cked !

Fri Jan 07, 2011 9:06 pm

he says he only had to put a bit oil in as it was almost full.
so looks like its fucked.
was told it was a good one but was also told that the wheels i bought aswell where good depite them needing 3 tyres and one of them was buckled.
lookin like it will end up on pistonheads

Fri Jan 07, 2011 9:51 pm

I agree with Pete, sounds like the pinion bearing will be toast. Entirely saveable but not a cheap or easy fix.

regards the choice of oil, the bearings are the same in open and limited slip diffs so the wrong oil won't have hurt it, this is simply an age related failure of the bearings (unless it was indeed run dry...?)

If you want to get it fixed or shift it, drop me a PM

Fri Jan 07, 2011 10:26 pm

is it common for it to fail completely or is the car still driveable ?
thinkin about putting a cheaper open diff in.

Fri Jan 07, 2011 10:44 pm

If it's screaming, it will start damaging the gears very quickly as they won't be meshing properly any more. It'll get you home and pootle about while you get another diff but keep the throttle low and avoid any extended speed or driving.

I have seen them melt the bearings completely solid before now!

The sooner you stop using it, the more likely it is to be saveable.

Fri Jan 07, 2011 11:51 pm

its a second car anyway so i dont have to drive it.
cheers for the advice