Diff problems

[genphreak]

What are the first signs of diff problems on a normal 535i (M30 auto) running the factory 3.91 open diff?

I seem to have a 'noise' down the back (really it is a light clunk) when the gearbox down-changes to second, as if there is some play being taken up back there. It might just be my centre bearing tho- and I am not really looking forward to pulling it all (exhaust, etc) out just to see.

Am hoping someone has found the reasons for these kind of noises before...

Many thanks in advance for any thoughts on the matter... Jeff perhaps you cna have a stab?

The car has done 180k miles. Have changed the diff oil regularly (does it need to be synthetic?) Last time I know Kriss and I used Castrol 85W/90 (I think).

[Paul in NZ]

not the rear dogbones is it?

[genphreak]

not the rear dogbones is it?Good suggestion, I didn't think of those ol' bones the bones! They are only 20k old and look okay. However I'll be sure to give em a good yank, it's too easy a fix to not be 100% on.

Thanks for the tip Paul...

[rob101]

yeah, wouldn't suspect differential problems based on that description.
diff's usually whining or horrifically fatal sounding noises (ie after stripped tooth).
clunk's most likely driveshaft/ suspension related.
I used some random gear oil in mine it was a castrol synth. only thing would be get 80W/90 or 85W/90 don't get that 140 summer weight oil though (thats the only other gear oil i've seen)....
oil in differentials is not that important whether its synthetic or not (if you change it fairly regularly ie every 15k or 20k kms. as its not exposed to fuel dilution, oxidation and range of temperatures as engine oil is.

I'd be guessing guibo or centre bearing (auto's don't have a guibo do they?)

[genphreak]

yeah, wouldn't suspect differential problems based on that description.
diff's usually whining or horrifically fatal sounding noises (ie after stripped tooth).
clunk's most likely driveshaft/ suspension related.
I used some random gear oil in mine it was a castrol synth. only thing would be get 80W/90 or 85W/90 don't get that 140 summer weight oil though (thats the only other gear oil i've seen)....
oil in differentials is not that important whether its synthetic or not (if you change it fairly regularly ie every 15k or 20k kms. as its not exposed to fuel dilution, oxidation and range of temperatures as engine oil is.

I'd be guessing guibo or centre bearing (auto's don't have a guibo do they?)Thanks Rob; all that makes me feel better :)

No guibo on the M30 autos in Oz, I am at a loss why there are so many driveshaft variables in the e34- I wonder why they used them in the US but not in (all) euro versions. Seems that many M20 and M50 cars have them though... If it turns out to be the centre bearing I'll have to pull it apart- (@#$%) it is not easy (impossible) to do without the right tools... still- am sure I can find a shop that can look after it. Cheerio Rob, hey- any news on plans for a north coast meet yet? You need to send those family members on holiday so we can all come up and throw a summer bimmer barbie...

[632 Regal]

supposed to use synthetic in the rear but dont think thats the problem. Clunks... guibo, motor/trans mounts, rear cv joints, dogbones? Time to go hunting to isolate the thing. Bring it over and we look for it... :D

[rob101]

Thanks Rob; all that makes me feel better :)

No guibo on the M30 autos in Oz, I am at a loss why there are so many driveshaft variables in the e34- I wonder why they used them in the US but not in (all) euro versions. Seems that many M20 and M50 cars have them though... If it turns out to be the centre bearing I'll have to pull it apart- (@#$%) it is not easy (impossible) to do without the right tools... still- am sure I can find a shop that can look after it. Cheerio Rob, hey- any news on plans for a north coast meet yet? You need to send those family members on holiday so we can all come up and throw a summer bimmer barbie...
well i've got my own place so its fairly spacious. only thing would be to try make it in the autumn summer is fast approaching and it'll be hot as.
I am working 30 kms west of brisbane and its already tipping 35 out there. brisbane itself has already had a few 32 deg days.

[genphreak]

supposed to use synthetic in the rear but dont think thats the problem. Clunks... guibo, motor/trans mounts, rear cv joints, dogbones? Time to go hunting to isolate the thing. Bring it over and we look for it... :DPhew! Thanks Jeff, Rob, two experts opinions, so now I can worry less. The trouble when coming from less well made 'run of the mill' rides is you always expect a major problem when on these cars its either wear and tear on body or electronics or age.

Wear and tear on the core mechanicals seldom seems to be a problem... I've new tranny mounts already, but I was worrying perhaps it might be the cv joints- maybe I'll have to pull them out and spin them around, it's about time to do that anyhow... got the brakes to do soon too so it might have to be a slightly bigger task... :) Nick

[bmwrp8]

What are the first signs of diff problems on a normal 535i (M30 auto) running the factory 3.91 open diff?

I seem to have a 'noise' down the back (really it is a light clunk) when the gearbox down-changes to second, as if there is some play being taken up back there. It might just be my centre bearing tho- and I am not really looking forward to pulling it all (exhaust, etc) out just to see.

Am hoping someone has found the reasons for these kind of noises before...

Many thanks in advance for any thoughts on the matter... Jeff perhaps you cna have a stab?

The car has done 180k miles. Have changed the diff oil regularly (does it need to be synthetic?) Last time I know Kriss and I used Castrol 85W/90 (I think).

i have the same problem that you described. change the motor and tranny mounts, center bearing (no guibo) and diff.oil still the same..if you solved your problem please post it on what you did thanks:D