During my last ride the bike broke up on me: could not shift gear anymore.
Decided to fix it. My last repair job on a bike was 30 years ago (fixed a gearbox on a CBR 650), so I will have to re-learn a lot, but I figured it is a good way to spend rainy days in the garage.
Will track my progress here.

One rainy day. Changing clutch assembley will take 6 - 8 hours, better with extra pair of hands.

I invested on oilproof clutchplate - just in case..

http://store.bobsbmw.com/product/clutch-plate---oil-proof-for-k100-k1100-k1

Cost me 210 euros (ordered from Louis / Germany). I think - knowing the problems with main seal - that this was a good decision. I dont have to worry about minor oil leaks anymore and if plate keeps dry it should last twice the mileage of standard plate. (Changed also main seal and some seals on gearbox etc.)

Looking forward to the posts mdangear.

Started removing things, already made my first mistake (I realized after reading more on the forum) by removing the cable from the clutch handle, so the rubber boot there is probably shot from the pressure that it got. Something to check when I get to it.


Could not remove the speed sensor so unplugged the other end of the wire instead, a good hint from this forum.
Got a jack to lift the bike, and using a sawhorse to keep it up while I will be removing the gearbox.

Ok, so this is where my ignorance starts. I read that I have to clean the gearbox cap and remove the small chunks of metal around the magnet, but I cannot get them out, is there a trick to this?
Also for the rear brake calliper, the manual just says to remove 2 bolts but if I do so the thing still hangs and I cannot really remove the footrest which is still tied to the brake etc... I cannot see detailed steps on this one either, is there something I am missing?

The gearbox filler and drain plug shouldn't normaly be any problem.

About the calipper, could be that your rear disc is a bit worn and have some grooves.
Try to wiggle the calipper a bit, to press back the pistons.

Footrest bridge is three socket head screws, don't forget to unbolt the reservoir and disconnect the brake light switch.

The rubber boot in good condition will hold the pressure of the spring on the clutch release. To remove the caliper you only need to remove the 2 socket head screws but as Inge said the caliper may need to be tilted each way to push the pistons back for the caliper to lift off the disc.
When you remove thr shock absorber make sure to support thr rear drive or it will drop suddenly and damage the rubber boot at the front of the shaft by crushing it.

Ok, thank you for the input.
All the Haynes manual says is to remove the rear brake caliper, but after poking some more I realize that the whole rear brake and footrest has to go in one piece: so unbolt the caliper, unbolt the brake fluid reservoir (allen bolt below the coolant reservoir), unplug the rear brake indicator wire, then unbolt the footrest and take everything out in one piece.

I bungee the right foot peg plate to the frame so I don't have to remove all that stuff like you did.

Remove the final drive today. Broke the wrench trying to remove bolts, so I went to get Liquid Wrench - thanks to this forum I know that this is better than WD40.



Looking good even though there seem to be water coming in.

when you pull the swing arm check the boot for cracks or being off not many ways for moisture to get in the swing arm lol my 2 cents

Removed everything I could, but the shaft does not seem to want to come off, and I do not see any clip to remove as indicated in the manual.
Same for the pivot rod for the clutch, I tried hammering it out, but it is stuck even after I removed the clip and washer.

The shaft has a spline on the other end. The only magic holding it in place is time and neglect.
Put some vice grips on the tail end and belt them with a hammer. Carefully of course.

rossco

There is an internal circlip in the spline of the UJ. If there is some rust which appartently is then this will make it very difficult.
Try puting dome diesel oil/fuel onto the spline where the shaft exits the gearbox and let it soak for 24 hrs then get a lever into the UJ and 3with the lever point on the gearbox case push forward on the lever with a solid thump and the shaft will be in your hand.

I smoked a cigar, relaxed, tried again using a screwdriver to get some leverage, and finally git it after trying from several places. indeed there is not much holding the shaft, but until you find the right spot it feels stuck.
i gave up on the clutch pivot rod, remove the rubber boot instead and now the lever is hanging there but at least it looks like i should be able to remove the gearbox.
back to the garage!

The bearings on the lever shaft lead a hard life there and if they are still pivoting freely then I just let the sleeping dog alone.

Remove the pushrod before you remove the gearbox except on a K75 where you can't get it out.

Rick G wrote:The bearings on the lever shaft lead a hard life there and if they are still pivoting freely then I just let the sleeping dog alone.

Sorry Rick, but I got the opposite opinion on this.

It would a good opportunity to remove the shaft now while a lot of this and that
is out of the way, and renew the grease in the bearings.

Try to add some heat to the gearbox tangs.

Inge K. wrote:

Rick G wrote:The bearings on the lever shaft lead a hard life there and if they are still pivoting freely then I just let the sleeping dog alone.

Sorry Rick, but I got the opposite opinion on this.

It would a good opportunity to remove the shaft now while a lot of this and that
is out of the way, and renew the grease in the bearings.

Try to add some heat to the gearbox tangs.

Inge I agree it should be fixed but letting it be is just my way.

After watching 100 times the german video on how to get to the clutch I gave up on trying to remove the pushrod first. It seems that I have a K75 pushrod on my K100



I have now the gearbox out. Lots of metal powder in the clutch area, I assume this is normal wear, or maybe this is the result of the problem I had.



The gearbox spline looks beat, not sure if this could be the problem. Or something in the clutch itself?



Done for today in any case, time for a beer and relaxation, I am just a weekend mechanic after all :-)

With the bearing stuck on the pushrod it would be ok but usually the pushrod stays in the spigot bush and there is a chance of bending it. It is a K100 pushrod the K75 has a small mushroom at the front and does not come out backwards.
Could you post some more pics of the front shaft from the side it looks like it is worn and US but it may be OK if I can see it better I will tell you. It would cause bad downshifting.

For Rick and other experts in this forum, something to chew on. How does this look?

Well I would use it if I had to but would replace it ASAP. You can often pick up a good used gearbox for a lot less than a new shaft. K1100 and K75 will do the job but K75 have a slightly lower 5th gear 1.61 - 1 for the K100 and 1.67 - 1 for the K75.
The K1100 is the same except for 2 tags on the bottom that take the paralever lower arm. There are some gear boxes that have the tags and are not drilled but esentially they are all interchangeable.
PS dont throw the old one out, they don't make them anymore and in the near future we may have to start fixing the splines.

Thank you very much for the input. From what I read it seems that this is not where the main issue was. Next is dismantling the clutch.

When you say it wasn't changing gears was the gear lever flopping up and down without shifting?

No, I was shifting gear and then the bike would make this high pitch noise and would not move.
I could feel the gear shifting but then it was as if the gear would not bite.

The closest I have seen in this forum to what I was experiencing is this:
https://www.k100-forum.com/t4301-clutch-problem

So far everything I have dismantled look ok, maybe not the best shape but at least good enough to be functional. Next for me is to dismantle the clutch itself, we'll see how it looks.

Looking at the pic of the clutch I cant see a spline in the center so that would explain things. It is very common for that to happen when the shaft wears like yours has.

Indeed, looks like there are no 'inner splines' left in the coupling plate.
I don't know if I would renew the shaft, can't see it well enough, but being pragmatic I would buy a new clutch plate and size it up on the shaft to see how much clearance there is. If you see an uneven wear on the shaft splines it should be replaced, but can't see that on the pictures as shaft mostly out of focus (for me :cyclops: )

Now that you mention, there are no teeth on the clutch side. All smooth. I like the idea of using the new piece to check the gaps on the shaft and confirm whether I need to replace, this is probably the best option.
Thank you all very much for the input, great to get support from all over the world, definitely makes me feel better when I am alone in front of the machine :-)

Keep after it mate and thanks much for sharing this!

OG

Finally got a 30mm wrench to remove the last part of the clutch.
Lots of oil in this area, not sure this is normal.

But the splines are looking really good on both side, so it looks like all I have to replace is the clutch plate, which had no spline left, plus the o-ring and self locking nut.





What should I use to clean the clutch area from all the metal debris? Engine cleaner? something else?

Make sure to block off the seal area so nothing gets into the engine and hit it with a bit of degreaser and wipe it clean with some rag.

Thank you for the input. This bring up another question:
I was advised to change the seal, but it looks good as it is, so wondering whether I should still replace it while I am in the clutch area, or leave it for now. The oil seem to be dripping from the o-ring rather than the seal, but not 100% sure.
Any input on this?

The O ring is the common place to have a leak but I will bet that the seal is at least 20 years old, now you and me were at our prime at 20 but that seal has had better days, its a good idea to replace as they do very often leak after being disturbed and for the sake of the cost of a seal having to replace the clutch again and all the work. Makes a new seal sound easy.

Ok, replaced the seal, drilled 2 holes into it and screwed self tapping screws to remove it.
Another great tip I got from this forum.

Getting ready to put everything back together, but I have a few more questions:
- the friction plate I got from BMW looks nothing like the one that was in there. 5mm thickness when the other is still at 6mm at least. Pads on the old one, none on the new one.
Wondering if it could be a problem when I put everything back together.



Then I noticed washers on the clutch cover plate that are not shown on the manual.
Wondering whether they are here to accomodate the different friction plate?



Some fell, some seem stuck to the plate. Do I keep the washers, or do I re-install without?

Finally I noticed that while I was doing all this there is a little bit of oil coming out of the final drive. Not really a leak where oil is dropping, but the area is wet for sure. From what I read in the manual it is recommended to leave this assembly alone, but I am curious whether this is something I should be concerned about or not.
Note that the final drive was lying on the side, rather than in its normal position. I have wiped everything clean and stored it in upright position to see if it happens again. Until then has anyone seen this before? Is this something I need to deal with?

Your old friction disc is non OEM, Luftmeister did have something similar which was
advertised as a reinforced race clutch.
The washers is added since the old friction disc is thicker, and you don't need them now.

The oil leak at your FD is coming from the seal that you can see behind the nut.
If it's just a small leak, you could still drive and keep an eye on the oil level.
But sooner or later you have to change the seal, a special tool have to be made up
to lock the FD, and another for the big nut with the four groves (the seal sits inside this).

Those splines begging for a lube................

Thank you for the input, I suspected the washers were an addition, I feel better having a confirm that it is ok not to do so.
And even better if I can live with the final drive as it is for now. I would rather not get to deep this time around.

Sidecar Paul (I think) did make lock tool for the FD some time back,
I'll guess you find it at the "how to" section.

Yes Inge it was me, but I put it in 'Special Tools'

https://www.k100-forum.com/t3247-simple-bevel-box-locking-tool

Paul.

I have to correct my earlier answer....it isn't neceserry to remove the
threaded ring with the four grooves to change the seal....only the big nut.

I got my local BMW dealer to replace the final drive seal, did not feel like getting into this with special tool etc... Plus the torque on that nut is big and I do not have this kind of wrench either.
$150 later I have a brand new seal installed.
Put the bike back together, turned the ignition key. Engine started fine.
Went into first gear. No problem.
Took the bike for a ride, feels perfect

A big thank you to the members of this forum for all the knowledge accumulated here, all the advice provided, directly or indirectly. I am very happy that I did this, a nice little project over the past couple of month. And now I know how the guts of the bike look like, which makes riding the bike even more enjoyable.
Cheers!

A suggestion I will offer is to lube the pinion spline every major service, at 10,000 miles. On Monolever Ks, removing the final drive to lube that spline is not terribly difficult (I don't remove the wheel or the shock, only the rear caliper to free up the brake hose and give you some room to roll the final drive back). That spline slides back and fourth with suspension movement and takes all the wear. Cleaning and lubing it at every major service extends it's life tremendously and adds maybe 15-20 minutes to your service time.

The only time the splines move against each other is if the uni joint end of the shaft is not properly pushed home onto the internal circlip which I consider to be one of the major causes of uni failure on the mono and paralever rear drives.
This will also cause major spline failure on a monolevers.

Jumping onto this old clutch fix post as there seems to be some good stuff here.

When you pull a clutch for a main seal change on the output shaft behind the clutch basket, how much dishing of the pressure plates is acceptable when doing this check for plane-ness with a straight edge?

Rick - I guess I am aiming this at someone like you Rick....
What is the worst amount of out of plane that you have seen on one that you have refitted AND got away with? If I put a straight edge from outer edge to outer edge of the plane surface on mine, I can get a 0.33mm feeler gauge to start to engage in the gap at the inner edge (if you follow me?)

The only time I have used a dished steel plate is when I have used the matching clutch plate which is worn to fit.
However at .33mm I would be very tempted to try it if it was my bike.  If the plate that came out is still worth using then use it, it will be matched.

Good point regarding the issue being far greater if rebuilding the clutch with a new or replacement friction plate...

Thanks for the reassurance Mate.

Have to say I am not impressed with the 'star washers' ordered from Bins. They appear soft as butter and looked to be splaying out in a mush instead of staying put under the flat land under the cap screw heads as design intended. Am convinced I would have been better off with refitting the originals - particularly in view of the time and effort to get them off the cap screws (yes I know the book says I should be using new ones)...

I have been using 7 x 1 x 40mm bolts from Repco (5 in a blister pack Champion brand) cut down to the correct length. They have hex heads and are reuseable. Star washers from same place.
I think I recall seeing them in super cheep.