clunkety,clunkety noise in rear 1994

[Philip A]

I have just driven 1000Kilos from Sydney to The Gold Coast. My 94 has 130K Km on it.
On arrival I have a loud clunkety sound from the diff area at low speed , particularly on overrrun in second gear at say 10-20MPH.
Jacked it up and checked the hubs for slop, no oil leaks anywhere from diff or gearbox. No undue slop in diff. The inner CVs have a little bit of slop, so that is my first suspicion.
Anyone had Cvs go?
Any other ideas?
I am taking it to a local specialist tomorrow to have a better look on a hoist.
Regards Philip A.

[gobuffs]

not a euro motor specific problem...you might get a better reply on the E36 M3 board.

I would check the subframe bushings, the rear floor to see if the subfloor has cracked, and the rear shock towers.

[GazM3]

not a euro motor specific problem...you might get a better reply on the E36 M3 board.

I would check the subframe bushings, the rear floor to see if the subfloor has cracked, and the rear shock towers.

+1
also have a look atthe diff cradle as it could be cracked/split. mine was cracked for a while, and once it split u couldnt drive it at all. easy to weld this up thou so its stronger than original.

Lots of ppl get upgraded chassis mountings for the diff cradle also so it dont rip up the floor. i need to get around and do this at some stage as a preventative measure

[Philip A]

Thanks for the replies. I didn't put it in the US area ,as our diffs and driveshafts are different, though similar.
The sound is a regular throb, throb which implies something that rotates . It varies load on (louder) load off ( clutch in-softer but still there) and less under acceleration.
So I think it is something that turns like a bearing, CV, crownwheel(ouch).
Regards Philip A

[morerevsm3]

3.0L rear end is identical to US 3.0L M3...

[Philip A]

Well, Its failed pinion bearings.

Went to a specialist here at the Gold coast and we put it on the hoist and ran it up. You could clearly hear and feel the pinion bearings.

So I have left it several days with a diff specialist to rebuild the diff.
Cost to be about A$900, as long as the crownwheel and pinion are not damaged.
Ironic seeing my son belts the hell out of his with burnouts etc etc and his is fine. I guess you have to expect it when you buy an old performance car.
Regards Philip A

[GazM3]

hehe maybe u dont drive it hard enuogh. should change ratio while its out. regular garden variety 188diff gearsets are redaly available. Al morerevsm3 has 3.62:1 in his and says its abit revvy on the road so perhaps a 3.46:1 would be good from the 3.15:1

[JamesM3M5]

The 3.46 is perfect in my car. Changing the gears will more than triple the rebuild price. That's not a bad price for new input bearings.

[morerevsm3]

hehe maybe u dont drive it hard enuogh. should change ratio while its out. regular garden variety 188diff gearsets are redaly available. Al morerevsm3 has 3.62:1 in his and says its abit revvy on the road so perhaps a 3.46:1 would be good from the 3.15:1

mine is 3.64, but have an E30 3.45 LSD to rob parts from to put in origanal 3.15 housing

[JamesM3M5]

Yeah, I was going to say that a 3.62 is a 210mm ring gear. But that's just semantics...

[Philip A]

The diff builder has called me to say that the CW&P are OK. Phew.
Quote is now A$1200 because of the cost of the seals and spacer( genuine BMW) and of course the BMW diff oil! which is in Australia about A$129 ( about USD 110) for 1500CC.
The guy seems to know his stuff and does the local GM warranty work as well as BMW and Merc stuff.
Regards Philip A

[morerevsm3]

bearings and spacer are available from any SKF dealer, and Castrol have same oil...but royal purple is better