bmwe21.net forums

yes, that is the sound..
and I guess it is normal on cars that have 30year behind them...

you can try swapping entire diff case to check for sure if diff is the problem.
it is 1h job I guess.

So you don't think it might be the gearbox, but the diff
Shouldn't a diff sound still be present at same speeds with neutral or when pressing the clutch?

my diff was making sound only when accelerating or keeping speed.
when I was deccelerating sound was... well there was no sound at all in that case

So you mean only when you had some gear "plugged", but not when you pressed the clutch (but speed was the same )

If its a diff producing noises, shouldn't a noise continue, at a given speed, even when clutch is pressed? As long as rear wheels are turning?

my diff made noise only when loaded
if I was runing 100kmph and pressed the clutch, there was no sound

here
I remembered my old videos
when loaded
https://youtu.be/ZDgCkUygp1g
and unloaded
https://youtu.be/80q7WKYpgpo

Thanks!
And what was the cause finally? Pinion? Bearings?

ring and pinion were slightly worn out.

I replaced whole diff case with another one.

It 's good to know
If ring and pinion wear is my case as well, then I think it's an easier replacement than taking out and opening again the gearbox for inspection etc

any updates?

No I 'm afraid.
Haven't had the time to look into the matter. It might take some time before I proceed to some opening because I should first decide whether I prefer the current 11-40 ratio (3.64) or, in case I replace ring and pinion, I might consider fitting a 11-38 ratio (3.45)
(just think that with the current ratio, with 3rd gear iirc I don't reach 100kph!!)

However, here's some update:

After the above discussion, I tried to identify once again when exactly I do hear the howling (or whining?) sound:

SO, as I already wrote, only if I have gear plugged in (especially 3rd-4th-5th), but the noise stops not only when I press the clutch, it also is not heard when I just take my foot off the gas pedal (even with gear in, and the car at speed) -this last one I think I have not mentioned so far (and maybe it helps better to figure out if it is the diff or the gearbox?)

So it is only under load, which doesn't rule out either of them. How fresh is your propshaft support bearing? Once had a noisy one, found out by using a lot of WD40 on it after which all was quiet again

Will have to raise the car again.
Now 1st things 1st, we have an MOT to pass, after that I will start looking into the matter

For me, if the diff noise is a constant wine, it's worn pinion or diff bearings, if noise is load sensitive then it's worn gears.

The lsd is irellevant as it's only working during cornering.
Mike

I had a whine which was way louder under load with my LSD and it turned out to be the ring and pinion