Hi Guys,
 when I bought my k100lt , both driveshaft and final drive splines were poor.

Motobins repaired the shaft and I bought a replacement final drive from motorworks.

The only concern with the " new box" was that someone had attempted to removed the input shaft seal castellated nut by using a drift, thereby bending over the four removal segments .. that should have been a warning I guess.

Ten thousand miles later and there is play at the back wheel and noise.

I split the box yesterday to find the stub shaft where the taper rolling bearing sits on, has picked up and the shaft is grey , so presumably now scrap.

I still have my original box, so my question is

 If I swap the crown gear set  over , do I need to find someone professional  to shim the unit, or would it be possible for me to do it.  I do not want to have pay out again , so I guess most replies would say  leave it to the professionals.

There is a guy called Jim Hill near Nottingham who can do the work, although he has a four week waiting time.

The repair cost including the seals and bearings which  I have already bought, will probably match that of another spare unit, but having it rebuilt should last forever hopefully.

Now had the previous owners carried out the servicing correctly, ....

Happy days, sun out and nothing to ride...

Bob

Your best bet here Bob is to fins a good used unit and have new seals and bearings as well as shims as required.
Mainly because each gear set is exactly that a set, they are lapped to match and to change just the crown gear would be a disaster.

Thanks for the info Rick.

I guess my current unit with wear on the tapered bearing shaft is now toast.

So now I have two final drives only worth scrap value...

and no spare bike to ride ...great...bloody car again for a while 

will give motorworks a call to see if they have a low mileage unit with good splines anywhere.. and of course scour e-bay

Cannot afford to have the next one rebuilt with new bearings etc so will have to hope the new one lasts this time.

Its a good job I love my K

Thanks Rick

Bob

Just found a unit in Europe with good splines, from a 1986 k100.

Have contacted seller for more fotos and hopefully the mileage details so fingers crossed.

Splines look rusty but unworn and the seal area is dry too...

More or less the same price as Motorworks.

ebay number 252639956801

Bob

Hello!

There is a good and friendly K dealer in Germany.
He is one of the biggest.

You could call or write him and ask for the part.
His EBay page 
http://stores.ebay.de/neumannwerke

Cheers

Thanks Chocolate,

I shall give them a call if I need to.  

Nice to find other sources of quality K parts..

Bob

Just had a look at that drive and it has a lot of rust on the splines which will wear the splines fairly quickly. To remove the rust is a problem in itself as bead blasting is effective but will erode the hardened surface and that will cause wear as well. Rust is very hard and sharp it will cause it to wear quickly.
The shaft does not slide on the spline but the rust will flake off and still cause a big problem.
There are a couple on ebay UK, I would be checking them out first especially the gold coloured one the other I cant get a look.

I have been looking around a few other places and I hadn't realized just how hard it is to get one in good nic. Have you considered putting a paralever on it as they are still fairly common but you would need a different shock.

Try here https://www.gumtree.com.au/s-ad/st-agnes/motorcycle-scooter-parts/bmw-k-100-rs-1986-wrecking/1085257966

It doesn't look like you are going the rebuild/shim route now, but in case you don't know, there is also Mike Overy at Overland an Classics (Valve of Belvoir). He is very proficient at all things BMW, well known for gearbox and rear bevel drive rebuilds.

Mike

Rusty looking splines often aren't rusty at all.  The factory assembly spline lube goop is red and when it gets dirty it can look like rust.

I have seen a lot of splines and never seen any that were actually rusted.

thanks for all replies,

I will ask the seller to clean the splines and see if it actual rust or just a residual effect that Duck says  it might be. 

Mileage is 65 k from the donor bike, so not excessive

The Gold coloured unit doesnt show the splines, probably for a reason. 

There is one in America with good splines, but the castellated nut for the input seal shows damage/abuse..

Rick, your suggestion of using a Paralever would be useful, except my rear shock is fairly new,   so I will stick with it.

Finding a low mileage spare is like rocking horse poo..

I will call Motorworks uk to see if they have anything low mileage and  good splines..  without any signs of abuse anywhere .

Bob

Bob. Chris Harris leads us to believe -  in his inimitable way - that the factory goop is "that white shit". The red dust you get by using that stuff (according to Harris) is classic fretting - it's an oxide of iron and is hard as Rick says but there are several ways to convert it if the "rust" can't be removed mechanically with a wire brush, a needle file or sand paper?
I wouldn't get him to clean it - tell him rust is a big problem and use it as negotiating leverage....

Another thing to consider if both the FD and DS splines are shot: go with the 85 and earlier 16 spline setup.  At least from all of the K bikes I've taken apart, (which is quite a few) the Z16 setup seems MUCH less prone to rear spline wear than Z20. Because of this, they also seem to be much more readily available in good condition.

ETA: They are available in either a 32/11(RT/LT) gear ratio or 31/11(RS.)

Since they are early, they are only available in silver, not black, if color aesthetics matter to you.

Bob - what do the thrust faces of the crown wheel and pinion teeth look like on the fd  you've taken apart?
I'm thinking you have little to lose by trying to rebuild this yourself if the loss of diameter on the 'grey section' of the shafts is not too far gone. Lack of interference (oversize on shaft diameter with respect to bearing inner race internal diameter) can be compensated for in some circumstances.

Thanks again for all the replies.

With regards to the rust  on the unit from Lithuania, it would be a gamble especially if I have to pay the return costs should the corrosion be severe. I have asked the guy to clean it and take fotos but I suspect that I will end up looking elsewhere.

The swap to 16 spline would be ideal, but I spent good money having my shaft refurbished.

But if a really low mileage unit come up then I will consider it.

As for rebuilding mine, the crown and pinion gearset look fine, whether the wear on the stubshaft is excessive is something I may find out wednesday when I visit the BMW guy in Nottinghamshire.

Rock and a hard place comes to mind...

Bob

Just noticed James Sherlock has 8v k100 rs box with only 12000 miles on it for £299  then I could get a good used shaft  for around £95..

Questions

1.  Are both 16 and 20 spline shafts have the same number at the clutch end..

2.. What effect on revs/ road speed would going to 31/11 against my 32/11 

Bob

The effect on revs is about 3%, at 60mph that's about 120 rpm.

Its marginal and not really noticeable.

When I did my final drive in March I had a choice of doing the one on the RT with or using the RS one that I have. In then I decided to do the RT one and keep the RS one. Both are 16 spline. I saw what the RS ones were fetching, £100 more than the RT one and there is no sense. 88 and I went to France in 2014 and his splines were not good, he put the final drive off his K75 straight on his LT and off we went. Was obviously revving higher but other than that no issue at all.

I was amazed at 80,000 miles the splines at both ends were really good but a leaking rear seal has a few advantages one being it lubes the clutch splines. All the seals were buggered so the final drive splines were oiled up too.

Trouble with paying such big money for the RS one you don't really know what you are getting and they are not cheap to go into. I needed the big bearing and seals and reshimming and added to the price of an RS one is the price of a project K! The good thing is that big bearing is same as the R bikes so plenty of them about.

The front end splines are the same for Z16 and Z20 drive shafts.

http://www.ebay.co.uk/itm/BMW-K100rs-bevel-box-/252963805675?hash=item3ae5d159eb:g:dhIAAOSwfRdZLDkJ

Bit cheaper and you can see the splines.

Dai wrote:Bit cheaper and you can see the splines.

They are worn in the centre of each spline from what I can see. I have 2 like that here, they would get you out of trouble but will wear the shaft splines very quickly.
Why not get a paralever gear set and machine the pinion shaft to the correct length. AFAIK the splines are the same.
Grandad PJ in South OZ bought a paralever 2.93 from me a while ago to do that with a lengthened K100 shaft to put on his outfit.

Thanks for all your thoughts guys.

Any spare unit from motorworks is around 285, nearly the same as the low mileage k100rs unit. 

Using Ricks suggestion might be too costly.

If the bmw guys in Nottingham say my crown gear stub shaft needs rebuilding, then that would be too expensive as well, although the box would be then as new.

The seller in Lithuania hasnt got back to me about their unit. 

The unit Dai showed has wear on , so I would be reluctant to use that on my new shaft .

Tomorrow in Nottingham will determine which way I go, but I suspect  more e-bay and  a call to Motorworks, who in fairness, are very helpful. 
If they have some, I can get there in an hour, and look at some .

Happy days....not

Bob

Took my final drives to the guys in Nottingham.

looking at both units , they said they would be reluctant to us either stub shafts as I pulled both bearings off by hand..

They had some spares , so unless they have  a 32/11 gear set with an undamaged stub shaft, and perfect splines, then I will be looking elsewhere.

They may suggest as Rick said, using  a paralever gear set and machining the shaft to fit..and again , as long as the splines are perfect.

That option will be expensive, but at least with all new bearings and seals, the unit will be good for a lot of miles..hopefully

Now waiting for the fone to ring....making sure I sit down before price is discussed...

Bob

they said they would be reluctant to us either stub shafts as I pulled both bearings off by hand..


Do you mean you used no heat and the bearing surface is scored? Was this at Jim's place



Mike

Hi Mike,

I managed to pull the taper bearing off its shaft on both drives prior to taking them to Jim hills place

Both stub shafts are a grey colour with some signs of the bearing turning I presume.

The drive that was on the bike when I bought it was quiet,  not sure whether there was play at wheel, it passed the mot so I presume it was okay, but the splines were shot..

I had my shaft refurbished by motobins and got a spare drive from motorworks with good splines.

Now, one year later, both bearings and the input seal are toast, so nearly a full house...

Now I have two drives which are scrap..

Unless Jim has a spare set of 32/11 crown and bevel gears with unworn splines and stub shaft, or the rebuild price is too high, then I need to visit motorworks..

Bob

I managed to pull the taper bearing off its shaft on both drives prior to taking them to Jim hills place


Did you heat up the bearing before pulling it off?

If the grey appearance is due to a bearing spinning, then the shaft is probably toast.

Mike

Hi Mike .

I pulled off the taper bearing whilst cold, on both final drives.. not a good sign..

The only interference on my drives , is the one on my wallet....

The guys in Nottingham have hinted that they may be able to make a good unit from bits they have .

Without appearing to be mistrustful, I would expect to be shown the parts they intend to use.

The low mileage unit from James Sherlock is very tempting, then ask  Motorworks for a 16 spline shaft.

The asking price is almost the same as any unit from Motorworks , at least the unit from James Sherlock shows the donor bike mileage.

I could then sell my refurbished shaft to pay for the 16 spline shaft.

This is probably the best and quickest way to get the bike back on the road..

If I had the skills and the tools I would refurbish a good cheap one, but I do not possess either, so sometimes you have to bite the bullet.

Cherish and love your final drive ..

Bob

I have just ordered the K100 rs final drive from James Sherlock, and will call Motorworks for a shaft.

If anyone needs a refurbished 20 spline shaft , let me know I will put in the for sale section when the bike is back on the road.  or a very dodgy pair of final drives.......

Thanks for all the advice guys.

The UK BMW Club has the various tools required for a final drive strip and rebuild (including the shimming measurements). You have to be a fully paid up member to access the the Tool Hire Scheme.

Mike

Hi Mike, 

that would be useful indeed if I had the time, but with the spare car out of action, and no second bike,  I need the bike back on the road asap.

Hopefully the low mileage unit will do the job, just waiting for motorworks to find me a good shaft..

With both stub shafts showing wear rebuilding would involve machining , therefore probably cost prohibitive.

Would have been  nice to learn how to measure and shim correctly.

Thanks again

Bob

Got the 16 spline  31/11 drive from James Sherlock , and unit is as new .

filled her with oil and slowly rotated by hand to get all bearing surfaces covered,  then slowly turned her over.

Very qiuet as expected with no play between crown and pinion gears.

!6 spline shaft arrived today from Motorworks and again no wear on splines as they had promised.

Spline lube and reassemble tomorrow.

Happy days again.

Bob

I think you made the right decision going with the Z16 setup.

I recently convinced a K75 friend of mine to do the same. On a K75 you give up a little oomph going from a K75 32:10 to a K100 FD but he is very happy with the results.

Thanks Duck I hope so.

Many years ago I drove a Rover sdi 2600 and the rear diff splines sheared off.

I was shocked at how shallow the spline depth was.  Even the Rover sdi 3500 v8 unit used the same set up.

What was the reason for BMW going to 20 from 16 

Bob

Got the bike back on the road today and oh so quiet .  no rear end drone to listen to anymore.

Just the cacophony from the front end....

Fresh mot too.

Revs slightly lower at cruising speed with the 31/11 final drive.

Happy days.... 

Bob