First Full Spline Job and clutch inspection - '93 K75RT 99k miles

[brichbk]

For reference this is a 1993 BMW K75RT with 99,248 miles that I just purchased 2 days ago.

So I started into my clutch inspection.  So far so good.  First a questions then the pictures


What do you do with the ABS Brakes and the saddle bag rack?  Currently I just have them bungeed up and out of the way (see pic).  I have only done the right side so far but will need to do both sides as I am going all the way to the clutch.





Now here is the splines at the final drive.  I don't think they look too bad, but I'd appreciate all your collective wisdom since this is the first time.  BTW what/why is there rusty looking liquid in the final drive and drive train?


Drive Train





Final Drive





My next step is to get to the clutch.


BTW I'm following along with Chris Harris video as I do this.

[johnny]

greetings...

dont wheelie with those splines until you have some spares in your tragkorbs...

j o

[The Mighty Gryphon]

Those drive shaft splines don't look very good.  Final drive looks a little better.  I'd be looking for a low mileage drive shaft ASAP.  A low mileage final drive probably wouldn't be a bad idea either, but it doesn't look as bad as the shaft.

If you have access to a machine shop, it's possible to replace the worn out splines on the drive shaft with a spline from the U.K..

https://motobins.co.uk/bmw-parts.php?model=K%20Series&bikeref=K100

K 20 SPLINE DRIVESHAFT REPAIR SERVICE K SERIES DRIVESHAFT SPLINE REPLACEMENT A known weak point of the K series before adoption of the paralever design was rapid wear on the output shaft splines that mate with the bevel drive. In 1986 BMW increased the number of teeth from 16 to 20 to give a greater surface area, however this did not entirely overcome the problem. We now provide a repair service for K`s with single shafts where the bevel end splines are replaced with a harder 20 tooth splined collar. Please note that these can only be used with the 1986 on 20 tooth bevel unit. Also check that the bevel unit splines are not worn as it is imperative that both units are in good condition for a long trouble free life. We give a one year guarantee on this service. We repair your original driveshaft and approx turn around time is 10 days. Universal joints are not replaced but are checked. It is important to remember to coat sliding surfaces with (95815) Optimoly T Paste on assembly.
 

K75 / 100 / 1100 Parts
 
 
Part No.55552REPLACEMENT SPLINE FOR 20 SPLINE SHAFTS.  [/color]( SPLINE ONLY-THIS REQUIRES WELDING OR SEE 55553 )
[size=.85em]£55.00 ex VAT[/b]
(£66.00 inc VAT)Qty 
[/size]

[size=.85em]or ADD to wishlist[/size]

[brichbk]

So I'm at the point where I need to jack up the motorcycle to take the center stand off and every time I jack it up it lists to the left like it's going to fall over. I'm guessing that the place where I'm trying to jack it up isn't in the center so that's why it's leaning. Any suggestions?

[brichbk]

Never mind on the lifting the bike question. Noob moment. Carry on. Nothing to see here.  :dunno :falldown:

[K1300S]

that driveshaft is toast.  don't bother putting it back on.  the final drive splines don't look much better.

get two sawhorses.  put a 2x4 through the frame where the battery is.  put the ends of the 2x4 on the sawhorses to hang the bike.  remove centerstand and trans...



hang the calipers and ABS pumps with zip ties.

[Laitch]

Now here is the splines at the final drive.  I don't think they look too bad, but I'd appreciate all your collective wisdom since this is the first time.  BTW what/why is there rusty looking liquid in the final drive and drive train?

I'll join the chorus of doom regarding the driveshaft splines. They could break at any time. The final drive splines are worn, too, but there might be a few thousand miles left on those.

The liquid in the final drive spline shaft could be a combination of gear lube and condensation. Drain the final drive fluid and have a look at it.

[brichbk]

Bummer about the verdict on the splines.  I'm guessing this is an indicator of what the transmission splines might look like.


On the upside I found the source of the oil leak.  The clutch boot is thrashed.



Tomorrow I should have the transmission out and we'll see just how bad this whole situation is.


Thanks to all of you for chiming in.  I appreciate it.   :riding:

[The Mighty Gryphon]

I think you might find that the transmission splines are okay.  Seems the wear is mostly at the final drive end of the shaft.  Because the front end is restrained by a snap ring that prevents the splines sliding the wear is less than the other end.  Also, wear at the clutch splines is mostly on the clutch, if there is any, not the transmission shaft.  The worst case there is that you might have to replace the clutch.  That's a lot less than replacing the transmission.

[brichbk]

I got the Transmission bell housing out, wow is it dirty.  I definitely want to clean it before I put it back on. What is the best way to clean the inside and outside of the transmission?


Here are the transmission to drive shaft splines





Here are the transmission to clutch splines





Do you think they look ok?


Here is the clutch.  Is that clutch dust and oil residue?  When I go the transmission apart it did leak oil onto the ground.






Once I get it clean enough to get the clutch plates marked I'll be talking those off next.

[Laitch]

The gear position indicator switch resides under the housing indicated by the arrow. Don't spray water onto or around this housing. Once you've cleaned the area, seal the whole unit with silicone or Plastidip to protect it from moisture. During reassembly, if you allow the clutch arm to drop, the new boot might tear so support the arm as the clutch lever cable is being hooked to it.

[brichbk]

Do you think all the oily mess is indicative of a Rear Main Seal failure?  I was thinking that I should replace the RMS and also replace the O ring as well while I have it all apart. Thoughts?

[The Mighty Gryphon]

What I look for with splines is nice wide flat top with sharp edges.  That is what they look like when they're new.  The narrower the top of the spline is the less life is left in it.

As far as cleaning the transmission, I scrape off as much as possible with a flat blade screwdriver.  After that, a small wire brush loosens up and removes some more.  Then I spray it with S-100 cycle cleaner and go after it a bit with a stiff brush followed with a good rinse.  After that, I can easily live with whatever is left, which isn't hard because I can handle it without getting my hands dirty.

As far as the inside of the clutch housing, I think some years had that finished with a black paint.

[The Mighty Gryphon]

If you're in that far, at least do the o-ring.  Those o-rings harden up over the years and stop sealing.  I replaced mine with viton, where the original looked like nitrile.  While I replaced the rear main seal, I'm pretty sure it didn't need it since there was very little leakage and what there was looked like it was coming from the o-ring.

[brichbk]

As far as the inside of the clutch housing, I think some years had that finished with a black paint.

What you said about the splines helps a lot, thanks. Also the clutch housing is painted black once I got the oily residue wiped away I could see the paint clearly.

[blackie1]

Gryph, are you able to identify the O ring for me , which you refer to in the above post.
cheers

[Inge K.]

# 11.

[blackie1]

thanks

[rbm]

On the upside I found the source of the oil leak.  The clutch boot is thrashed.

Tech tip:  Once you do replace the torn clutch boot, don't ever allow the clutch actuator arm to hang free like that.  Make sure to secure it to the transmission housing using binding wire through the clutch cable hole and the clutch arm end, like this:


The reason the boot is so torn up is the internal spring's tension is much stronger than the rubber's resilience to it, and the spring tears the thin membrane.

[brichbk]

Thanks for the tip RBM.


Where is the best place to get parts?  Do I have to get them from BMW?  I see some parts on bikebandit and Bob’s BMW. But what about the clutch boot, RMS, and friction plate (if needed)?  I’m hoping to get parts ordered today.

[The Mighty Gryphon]

I get my seals, o-rings and bearings at the local industrial bearing supply house.  Their prices are usually pretty similar to BMW's prices, but they almost always have what I need.  For OEM parts, I always look at eBay first, and then MAX BMW.  If you're careful, you can get some good deals on used parts.

If you need a K75 friction disc, I have a used one here that has a lot of life left in it.  It's 5.45mm thick.  New is 5.5mm and the wear limit is 4.5mm.  $80 and I'll pay the shipping.

I think I have an O-ring too that I'll toss in if I can find it.

[brichbk]

I got the clutch rings out and found my friction plate is 2.5mm, looks like it needs replacing.





the rest of the parts seem to be ok.






There is oil gathered below the nut probably means that the O ring has failed, is this correct?  Either way I'm replacing it.


Now to get the clutch nut off.

[The Mighty Gryphon]

2.5mm!!!  Are the rivets exposed?  Have the rivets torn up the other plates?

[brichbk]

2.5mm!!!  Are the rivets exposed?  Have the rivets torn up the other plates?

The engine side of the friction plate rivets are below the surface.  The outer side are also just below the surface.  The metal clutch rings surfaces feel the same and don't seem to be gouged. 

[The Mighty Gryphon]

2.5 doesn't sound right.  Have you double checked the zero on your calipers?