Clutch slipping @ high revs ?

[79beem]

 My 79 R65 has recently developed a possible clutch issue. It frist happened when overtaking a car that was doing 80kmh in a 100 zone + as i accelerated past it the bike revved out with no more power to the wheel @ 7000rpm. It has happened again @ a lower speed 60 < > kmh @ 7000rpm.  I have previously had the revs @7000rpm + higher  with no probs.

Is this an early warning my clutch is on the way out?

[Bob_Roller]

I'd first check the clutch cable adjustment .

Possible oil contamination from either the  engine rear main seal, or transmission input seal .

How many kilometers has the bike accumulated ?

[nhmaf]

Are you sure it isn't dropping out of gear, rather than clutch slipping ?   Does it "bite" and pull again simply by lowering the RPMs, or do you end up manipulating the clutch lever and/or the shift lever as well at any point?

[79beem]

62k km on the clock, revs out with no power @ 7000rpm. Drop the revs 250-500 and power back 2 wheel, no clunking,grinding, just smoothly reengages. No clutch or gear lever fiddling.

[nhmaf]

It does sound kind of like it then.

Can you see any oil on the underside of the engine/gearbox, particularly on the "shelf" that projects back toward the swingarm from the bell housing area - the clutch/flywheel are contained within the flared bell housing area and if there is an engine rear main seal leak (or possibly transmission input shaft seal leak) then the oil will enter the bell housing area where the clutch is and eventually drip down onto the shelf area.

If the clutch isn't oil contaminated, it is possible that it is worn and/or the diaphragm spring in the clutch has weakened.

[79beem]

There is oil leaking but from the neutral switch. The free play @ the clutch release lever ( tranmission end ) is about 3-5mm.

I went for a spin yesterday, and she was stubborn shifting up a couple of times.  (gear shift lever would'nt move until i released the clutch lever slightly).She revved out again a few times around 7000rpms. Is this still sounding purely like a slipping worn clutch/spring or am i looking into the dreaded gear box department?
 
Has anyone replaced a clutch?
How much time am i looking @?
How many times am i likely 2 swear and curse?

My manual warns against reassembly without the clutch alignment tool, has anyone got any suggestion for or against?

Cheers for the advice so far Bob and Nhmaf

[Rob Valdez 79 R65]

All you will really curse at is the cost of the parts.  Installation is fairly straightforward.
The clutch alignment tool is NOT expensive.  There are those that say it is not needed, but I've had one in my toolbox for so long, I don't think about it.

Your difficult shifting could be caused by a lack of lubrication on the gear box input splines.
I recommend Honda Moly 60 for that.  Easily sourced at any Honda m/c dealer.

It is also recommended that you replace all of the clutch parts at once.  Any worn parts you leave in will have a detrimental effect on the new ones.
http://www.realoem.com/bmw/showparts.do?model=0363&mospid=51897&btnr=21_0068&hg=21&fg=05

And you will need 3 long 6mm bolts w/nuts to remove the clutch safely.
You remove 3 of the six (every-other) and replace them with the long bolts w/nuts.  
Take the nuts down to the clutch plate so they are securing the assembly.
Then remove the remaining 3 clutch bolts.
Then slowly back off the nuts to release the pressure on the spring.  If it doesn't start to come apart, smack it with a small rubber mallet a couple of times.  

Use new clutch bolts & wave washers on reassembly.

Check your input splines for wear.  Only put moly grease on the input splines, not on the mating splines of the clutch disk.  Also put a dab on the tip of the throwout rod.  Inspect the tip of the rod for abnormal wear.  See Duane's link at the bottom of my post for pictures.

Inspect & lube your throwout bearing (#4) http://www.realoem.com/bmw/showparts.do?model=0363&mospid=51897&btnr=21_0069&hg=21&fg=10 with gear lube or regular axle grease.  NOT the moly!

Here is what Duane Ausherman has to say about the alignment tool.   I've never tried it:

"L.  BMW clutch installation

The various books call for a clutch alignment tool to be used when reassembling the clutch.  That tool is available from Ed Korn and saves a bit of time.  It is nice for a BMW shop to have.  For the occasional BMW mechanic it is unnecessary to have that tool.  Hand tighten the 3 long clutch bolts so that one can still grab the friction plate hub and move it with some effort.  Then use the actual transmission to align the clutch.  Just slide the transmission into place and move it around until it fully seats.  Then very carefully slide it back so as not to move the clutch friction plate.  Now, tighten up the 3 starting bolts enough to start the 3 shorter bolts and tighten them.   Remove the 3 starter longer bolts and install the last 3 short bolts.   Now tighten all 6 screws.  The transmission should go back in easily.  If the /5 and later transmission "seats" in place, then all is aligned and you are done.   Some mechanics just use a mirror to hand center the friction plate and tighten the bolts down."
http://w6rec.com/duane/bmw/clutch/index.htm

[nhmaf]

One thing you also need to consider is that if your neutral switch is leaking gearbox oil - some of the difficulty in shifting may be due to low gearbox oil level!  Put the bike on the centerstand on a flat location and remove the filler plug on the side of the gearbox near the shift lever.  If properly filled the gear oil should be up to the bottom of the hole.

I wrote an article for our wiki section on replacing the clutch based on my performing the job on a 1982 R65.   While the clutch assembly and the throwout bearing assembly on your 1979 is a bit different, the whole process is very similar and this should be helpful - plus you have the other sources that Rob referenced.    Our wiki section became corrupted some time ago, so I had made a PDF file copy of the article and posted that, but it seems to go missing, so I'll attach a copy here for you.  We should probably make this a sticky note in the tech section (?) unless/until we get the wiki working again??

-Mike

P.S   Eureka - the earlier post is still there (my bad!)  here is a link to it:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1289518138

[Bob_Roller]

I've had the clutch/flywheel off 6 times and I've never used an alignment tool, but I have bikes from '81 and newer, so they have the lightened flywheel, commonly called a 'clutch carrier' .

You can position the clutch plate with the bolts loose get it equally spaced on the pressure ring/pressure plate, then tighten the bolts up .

I don't know if that is possible with the bikes made prior to 09/81 .

[Teo]

I also have had the transmission out and clutch off both my R75 and the LS many times without using a centering tool.  Eyeball the clutch disk centered and then tighten everything down.  Mount the transmission with loosely tightened mounting bolts.  Adjust the clutch.  Start the engine and pull the clutch in three or four times.  The transmission will move around slightly as it centers the disk and then settle down.  Tighten it down and verify the clutch adjustment.  Bob's your uncle.

Teo

[79beem]

Problem solved?

I recently checked transmission oil and got a bit of a shock when i took the plug out and out came way 2 much oil. (Bike on center stand,engine cold). I didnt get to measure it as it was panic stations with oil going everywhere.

As i have previously posted, I'am also having issues with final drive leaking and drive shaft oil dissappearing. Guess i know where its going now...... top up drive shaft oil and off to the transmission it goes.

Since resetting oil levels, the clutch has stopped slipping at high revs although makes a small "squeak" when  changeing down going uphill. Gear shifting issue seems to have stopped also.

Would the high oil level have caused the slipping and gear issues??

And from what I've mentioned re final drive and drive shaft which seals need replaceing in your collective opinions??  

[nhmaf]

I've seen oil migrate from the swingarm into the final drive.  I've heard of (but not seen) oil leaking from the gearbox into the swingarm.   But, I've never heard of the oil going 'uphill' (at least, usually it would have to be uphill) to get out of the swingarm into the gearbox.   There is usually only 125cc of oil in the swingarm anyway, so I cannot see how that could cause overfilling of the gearbox.   Often, if there is much oil making it to the rubbber boot at the swingarm pivot, it will drip out there.

With highly overfilled gearbox, it could be that gearbox oil would leak out in various places that it wouldn't normally.  There is a seal on the input shaft and the output shaft that if really overfilled, could give way and cause oil to come out of the gearbox, I suppose.

[79beem]

I was regularly topping up drive shaft thinking leak from final drive was drive shaft oil, but after talking to a beemer mechanic he said if tranny oil levels increased then oil was travelling to it from the drive shaft via a shot seal.

Im sure I've read here about drive shaft oil travelling to tranny, any how it was chockers.

[Barry]

I've only ever had oil migrate from the drive shaft to the final drive but snowbum reckons it can go the other way if the gearbox breather is blocked.
http://bmwmotorcycletech.info/oiltransfers.htm

[Bob_Roller]

You need to check the bolt that holds the battery ground/earthing cable .

I've gotten two LS's in the last two years and the special hollow bolt the acts as the vent for the transmission was replaced with a solid bolt on both bikes .