Now I reckon the splines on the driveshaft are knacked but the diff is just about ok. But, then again, that could me lying to myself again. Any thoughts would be gratefully received. Can anyone recommend anywhere in the UK to get this work done by any chance? I have heard Motobins do a refurb but is there anywhere else? Thanks for looking.

those splines look quite worn ....
and my guess, will cause a new tail shaft to look like that old one pretty soon
I had a tailshaft that was a repaired one with that reweld process new outer spline ...
 but when installed still had a fair bit of movement ...meaning it seemed to a close fit ...not a tight one, some 60,000 ks and its toast.
don't know in fact that the add on section was indeed the same that motoworks etc sells ...but worth investigating a bit further .

have replaced the shaft with a original bmw unit and its tighter than repaired shaft ever was  ...wonder if there is a slight difference between the rewelded add on spline and the bmw units ...
just a heads up

Bruno's has one heck of reputaion for bmw splines. he might have something in stock.
he also gives you the option for a u joint with grease fittings.
located in canada.

http://www.brunos.us/index.html

They both look no good, not sure there are any refurb guys in the UK, if you have no luck PM me, i have a good diff and its original drive shaft from a late low miles (1990) K100rt, £95 the pair.

Ben

At 95 quid the pair you wont go past that.

Thanks for replies; ok, my bits have lost their usefulness.

Ben, I'll be making contact, that's a great offer, thank you.

I got a brand new genuine bmw drive shaft, £100 you can have it, better than all them "repaired" things....

john..

Pm me if interested.

G'Day All,again,this subject has most likely been covered before but here goes.. Decided to change all the oils in the 93 75S after the run down to Robertson with Gaz and Ulli.The oil out of the gearbox was as clean as but the oil out of the Final Drive was pitch black whereas previously was pretty clear.Any advice on this issue much appreciated.Thank you in advance. Cheers Tom

Unless there was some metal flake on the drain plug I would not be overly concerned. Put clean oil back in and keep an eye on it. sometimes the plug gets furry but so long as you cant feel any grit in it
Did it smell burnt.
It's possible that you used a different brand last time with a higher detergent content and it lifted all the black residue from the inside and drained it out.
I can't think of anything else in there that would cause the oil to get like that.

G'day Rick,thanks for reply.Have not given it the sniff test yet but will get back to you on that one.No metal bits on the plug and I can't remember if a different brand of oil was used. Will lube the splines which lool pretty good, and put it all together and keep an eye on things.Cheers Tom

yep have pulled a fair bit of black stuff out of the rear diff during a pull down tom ...

hope it goes well mate ...

cheers !

Hi There,

Now, i am now expert on this, cos it is a long time since i had one in bits, but so far as i can remember, if teh rubber gaitor between the gearbox and swing arm is knackered, all muck and water gets in, runs down inside the swing arm, and straight into your final drive, hence contaminated oil.... Not good!!!!

john..

No John, the 'muck/water' can't get past the final drive oil seal.  

Paul.

Ahhh, i see!! Wonder where the crap comes from though.. Must get in somewhere.. Say i take the top off my lathe gearbox, the oil looks the same as when it was put in there, nice and clean. Wonder if it sucks in as the final drive heats up and cools down?? No idea really!!

john..

Thanks Charlie, there was no 'burnt' smell but before taking the FD off,there was a bit of a rumble whilst turning the wheel.Another thing was that FD and gearbox oil were drained into one container.
Measured the combined quantity of oil which was about 950ml, well short of the 1110 ml required.Pretty sure that 260ml were put into the FD on last change.
Thanks for any advice. Cheers Tom

Only a wild guess here, possibility though... What is the chance that the final drive was a bit noisy, so someone put some "molyslip" in with the oil???? Now that would make it black. So far as i know, only two things make oil black, one; dirt two; oxidation of the oil. Cannot see the oil in a diff getting hot enough for that, but then again, if you drained out, say, a car axle years ago, it was always black....

I would just put in clean oil and see what happens... Cannot hurt.....

john...

Tom Grabau wrote:Thanks Charlie, there was no 'burnt' smell but before taking the FD off,there was a bit of a rumble whilst turning the wheel.Another thing was that FD and gearbox oil were drained into one container.
Measured the combined quantity of oil which was about 950ml, well short of the 1110 ml required.Pretty sure that 260ml were put into the FD on last change.
Thanks for any advice. Cheers Tom

When there is no oil in there they will rumble a bit as the oil damps the noise. All I can suggest Tom is to put the new oil in and check it again in say 1000km and see how it is. Just dip something into the hole and check that way.

Was there much gear oil near the FD input splines when you took the FD off? At this age it's not uncommon for the pinion seal to have grown hard and start leaking.

Thanks Duck,yes I thought the FD input shaft area was a bit sloshy perhaps some oil mixing it with the spline grease. Will keep a lookout and report back.Cheers Tom

G'day All, Have covered about 500k since last FD oil change.Checked the colour of the oil and it was already blackening.It seems as though oil is getting past the seal into the spline area and vica versa. Any thoughts on this issue??? Thanks muchly in advance. Cheers Tom

Hi Tom, Have you lost any oil? Has the level dropped significantly.
From memory the oil was fairly black at the last change and that 90 gear oil is hard to drain all of it so may just be contaminated by the left overs.
I have come across a thread on a forum elsewhere that the guy claims to have put 200ml of oil into the swinging arm and let that do the lubrication of the splines, he claimed it was quite sucessful.