I lucked into a low-mileage bike, but time has the potential to do nearly as much damage. It finally snowed here so I couldn't really put it off any longer. Let's dig into this thing and see what we can see...

Getting this far was amazingly easy...the bike is built so modularly:


Splines look really good...far as I can tell:




Next to pull the swingarm/driveshaft so I can get a better look at it:

Looks like the splines would appreciate their first lube in many years .

Inge K. wrote:Looks like the splines would appreciate their first lube in many years .

Yes, looks like I dodged a bullet--they are pretty darned dry. FWIH that red patina is from the "stock" original lube.

My bigger concern is going to be how to know whether the sealed Uni-Joint is O.K. or not.

BTW---congrats on the distinction, Inge. Definitely well-deserved!

[quote="zaubertuba"]

Inge K. wrote:BTW---congrats on the distinction, Inge. Definitely well-deserved!

Thanks! .

The only way you can gauge if the uni joint is OK is to work it about by hand and feel for tight or rough spots.
They can be very tight but OK it's tight sections that show problems.

The rubber boot on the swingarm is still in good shape--flexible, supple, no cracks:






Swingarm bearings seem OK--no slop, and they even feel greased yet...should I still clean/regrease them anyway?




Not a great picture, but the driveshaft splines seem good as well (that's not metal wear on the edge, just old grease).





Output shaft splines need grease like all the rest, but are in good shape. Note there's no leakage from the rear seal, either. Yayyy!






Now, about that uni-joint:





There appears to be either extra grease flying off one pair of the joints--or maybe it was just from an assembly. In any case, the joint with the "messy" bearings seems OK--at least it moves smoothly through its full range of travel. The other joint moves smoothly (same effort as the first joint) through about the center 10-degrees of its travel, but gets much tighter through the final extreme travel on both sides.

Neither joint seems "sloppy," but the difference in resistance on the one joint is pretty substantial. Not "grindy" at all, but definitely much tighter.

Thoughts?

You're doing well, all seems OK. I would say from your description that the uni joint is a bit tight when you go past its working range but is OK.
I would regrease the swing arm bearings as they aren't well protected from thr elements down there. To get them apart put a screwdriver in the centre and give a sharp jerk but make sure you can catch the rollers as they tend to come out at the speed of light and dissapear into a dark corner never to be seen again. Use plenty of grease so it builds up around them to prevent water ingress. If the plastic frame that seperates the rollers is broken a bit I just reuse it as it's not like they do any great speed.

The tranny came out just fine...splines look fine...






But...there's an awful lot of oily/dusty residue that looks like it's been sprayed all along the inside of the bell housing:



This isn't normal, is it?

Nope. Propably the main seal is leaking. It is easy to put wrongly and tend to leak anway. I happen to have one extra seal, but I think you get it sooner from local dealer (if it is that seal that leaks). If the gearbox is not leaking its oil, then there is only main seal and one O-ring left if I have understanded correctly. (Awful english...)

Here is one thread about this seal: https://www.k100-forum.com/t4887-engine-output-shaft-seal

I'd say it's the main seal leaking, not bad by any means but while you are in that far replace it as a matter of course, it is 25 years old after all.

As Tenox and Rick says it's a leaking main seal (and/or o-ring), not that unusal at our old bikes that they dry out.....all the dust comes from the clutch (quite normal).

You need a new main seal and o-ring, .....the nut and compression washer in front of it is a one time use...but some have reused them w/o problems (I would have changed these ones too).

It could be a good idea to order the six screws and washers at the clutch housing at the same time as they tends to be destroyed during dismantling (rather soft)....these are also a one time use according to BMW.

Mark up the clutch parts before dismantling, so it's put together in the same position related to each other.

All great tips, TYVM!

So, so far, I'm needing a new rear seal, the O-ring, nut and compression washer, and clutch housing bolts/washers. Anything else bear replacement?

Do I assume correctly I'll need a new clutch plate, or can it be salvaged?

I can't see any reason not to use the existing clutch assembly, it looks dry in the pics, just mark it up as stated earlier.
did the clutch slip before you stripped down??

As ungaas says if it's not oil contaminated, it's no problem to reuse it.

But also measure the thickness....a new one is around 5,3 mm, service limit is 4,5 mm.
So if start to get close to the service limit, it would be a good idea to change it,
while things is apart........

I assume that when you get the parts you would get a seal with teflon lip (single lip),
this seal sould be mounted 0,5 mm proud of the surface.

Inge K. wrote:As ungaas says if it's not oil contaminated, it's no problem to reuse it.

But also measure the thickness....a new one is around 5,3 mm, service limit is 4,5 mm.
So if start to get close to the service limit, it would be a good idea to change it,
while things is apart........

I assume that when you get the parts you would get a seal with teflon lip (single lip),
this seal sould be mounted 0,5 mm proud of the surface.

Thanks Inge - I guess we'll see when I get the clutch off.

About that grub screw - I think the PO actually did the same repair not long before I actually got the bike. Anything I need to do to make sure the fix lasts? Get a new grub screw, maybe?

zaubertuba wrote:About that grub screw - I think the PO actually did the same repair not long before I actually got the bike. Anything I need to do to make sure the fix lasts? Get a new grub screw, maybe?

I don't see any need in buying a new screw, unless the old one has damaged
threads or hex.

Use blue loctite on [clean and oil free threads (both male and female)],
clean the threads with brake cleaner.

Thighten to 17 Nm, leave it undisturbed for 24 hours in room temperature.

zaubertuba wrote:About that grub screw - I think the PO actually did the same repair not long before I actually got the bike. Anything I need to do to make sure the fix lasts? Get a new grub screw, maybe?

I'm assuming you mean that annoying little one on the gear shifter shaft? Depending on how long it's been loose, you may find that you want to replace the shaft.. Wearing steel-caps when I ride, I didn't notice the slop in my gear shifter until the screw had backed off almost all the way, and I couldn't get out of second gear one day (yeah, that was a 'fun' 60km ride home from work..).

Mine is now all back together, but my shifter has a permanent ~1/2" slop in it because the hole in the shaft is now more of an oblong than a circle.. If I'd realised that before I put it back together, I would have looked at replacing the shaft..

Cheers,

DG

Am following this thread closely because I too recently bought a low-mileage (56k mi.) '85 K100RT.

Finally removed the rear end to lube the rear spline for the 1st time and found it in similar shape as your's, squared-off teeth and red grease.

So, am greatly relieved and wanted to say thanks for posting your progress.

AJ.Valente wrote:Am following this thread closely because I too recently bought a low-mileage (56k mi.) '85 K100RT.

Finally removed the rear end to lube the rear spline for the 1st time and found it in similar shape as your's, squared-off teeth and red grease.

So, am greatly relieved and wanted to say thanks for posting your progress.

Yes, squared off = good. "Sharks teeth" = bad. I suppose we both dodged a bullet there since lord knows when that old red grease started drying out.

Gearbox apart:




And here's our little culprit (definitely "hanging out" quite a bit!:



Inge - How the heck do you get a torque wrench to this without removing the mechanism?



An electronics tool comes in handy for cleaning some gunk out of the threads:


....and the tranny cover makes a good "soaking pool" to try and loosen the gunk up:

Rendrag wrote:...my shifter has a permanent ~1/2" slop in it because the hole in the shaft is now more of an oblong than a circle.. If I'd realised that before I put it back together, I would have looked at replacing the shaft..

...and...yep, it looks like I've got some serious ovalage happening here:



When I seat the grub screw in the hole, there's definitely a little play there, so it's looking like I'm going to have to find a new shaft.

zaubertuba wrote:Inge - How the heck do you get a torque wrench to this without removing the mechanism?

You got to remove some of the mechanism to get any kind of tool in there.

Would this shifter shaft be compatible?

just an idea ....

could the shaft be taped to the same thread as the stud .....and a longer stud found

i say this as i can see a conical positioning friction fitt , with some of the metal worn away it might take a thread at least part the way through the shaft ,maybe 10mm deep .

with a new stud maybe 10mm of thread longer (cone part no longer required ) and some good locktight , wouldnt this position the changer shaft and lock it together .

one would need to be carefull to make the start of the thread in the shaft line up with the grub screw ?

anyhow just a left hand observation .

zaubertuba wrote:Would this shifter shaft be compatible?

Same shaft is used on all models from K75 to K1100.

Inge K. wrote:But also measure the thickness....a new one is around 5,3 mm, service limit is 4,5 mm.

Well, the rivets looked awfully close to the surface when I pulled the clutch plate, so I measured it. The verdict? ...




...4.5 mm

Going to have to wait 'til payday to get a new clutch disk. Oh well, guess this drivetrain's going to be nearly brand new when I get done.

Same shaft is used on all models from K75 to K1100.

I bought it. The screw and fit on the actuator arm is still factory tight. I figure I'll take it apart, clean, and re-torque/locktite it anyway just so I'm sure this one won't come loose on me.

An ounce of prevention....

Found much better clutch prices (probably even with shipping) on the Moto-Bins site. Anyone have experience with the Italian aftermarket or "heat-resistant" versions, or should I just go with the stock/Sachs plate?

http://www.motobins.co.uk/bmw-parts.php?model=K%20Series

I bought the one with oil resistance mentioned. It is expensive, but they claim it would be twice as durable if it keeps dry and still as durable as original if it gets oil on it.

http://www.louis.de/index.php?topic=artnr_gr&artnr_gr=60190300&lang=en

(Siebenrock 60190307 OIL-RESISTANT DRY CLUTCH K100/K1100/K1)

Looks like the same one that on your link (174£ inc. vat)

(I'm just tired of oil leaks and this way I can ignore the next one )

Having a real problem with the Credit Card authorization with Motobins, and money is still tight. Found this on Fleabay:

Clutch Assembly

5.15mm would give me quite a bit more time...whaddya think?

So the first wires from the self-tapping screws...broke...


....tried to pull the self-tapping screws with a prybar..they pulled out...


....used heavy steel wire and chain with a 2 x 4 to try and pry the whole thing out...and a couple of the holes actually broke out...




What to try next...a blow torch?!

drill a line of small holes from inner to outer .(2 or 3mm maybe ) ..then you can prise the seal at one side and roll the most part of it away like a tin of sardines lid ...use something like pliers to grab it and fold it out ...the outer of the seal may then collaps a little letting go of the circumfrence ... using a dremel tool and cutting blade would leave too much grit in near the bearing ....the drilled metal should come out easy, pickup all the chaff with a magnet ?

or metal cutting sheers to cut from inner to outer ...and roll it out, same tchnique if your worried about the metal fillings

Cant really see what is the big thing on this removal. I took out that seal from my bike with Knipex pliers. ( http://media3.rsdelivers.cataloguesolutions.com/LargeProductImages/R1585451-25.jpg ) It came out with no problems and in one piece without any drilling or anything.

I'm with tenox where is the big deal you have to be a bit brutal without damaging the thread.
I made a tool similar to this one years ago but they are not expensive.

Check this out if you are in the USA? I failed to notice your location
It measures like new

http://www.ebay.com/itm/221200416260?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

No problems so far, but then again I'm not out there popping wheel stands or abusing it in any way.

RickG wrote:I'm with tenox where is the big deal you have to be a bit brutal without damaging the thread.
I made a tool similar to this one years ago but they are not expensive.

Sometimes it takes just the right combination of leverage and grip in the right spot--Rick a tool just like that ($8 at the local Napa Auto Parts Store) did the trick. Like Butter!

New seal installed with bellhousing cleaned out--Just taking my time with a 2x4 block and a hammer did the trick--seated a hair above the rear of the engine housing:






Laughing is allowed on this next part...

You got to remove some of the mechanism to get any kind of tool in there.

So, I got the new shift shaft, and thought I'd be smart and get the set screw lock-tited and torqued in the cozy warmth of my own home. Sure enough, I got it all snug and tight and ...ready...to....go...






...oh wait...what's wrong with this picture?

ibjman wrote:Check this out if you are in the USA? I failed to notice your location
It measures like new

http://www.ebay.com/itm/221200416260?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

Wish I'd seen that a week earlier...already ordered and installed the other one by the time I'd seen this. Thanks, though!

Oh senior I theenk you forget the gearbox. But I wont laugh