Slipping Clutch? .... (I think)

[barcelona_r65]

My 1980 r65 just got an overhaul at the mechanic.  It had been off the road & garaged for a 3 years or so due to personal reasons (a little baby boy) but now it's back in action.  Something that I had nearly forgotten was happening when I parked it was what I suspect is a slipping clutch ... here's the story.

SYMPTOM #1  ...several times, in the past, I had had to "push-start" the beast due to a dead battery ... in the beginning (8 years ago) it worked just fine ... but in the recent past I was unable to get the engine to turn over when I tried to "pop the clutch" ... it just didn't catch ... I'd work up a good sweat, but no always had to turn to the jumper cables.

SYMPTOM #2  ...When I let out the clutch and accelerate, I sometimes get a "squealing" or "whistling" sound as she accelerates ... normally when I seem to let it out at low revs ...

I don't know what to do or try ... loosen the clutch a little? Something else?  

Any suggestions?

Thanks!

[Bob_Roller]

Check the clutch freeplay adjustment, you should have 2-3 mm freeplay at the clutch lever.

How many miles, or kilometers are on the bike ? May be worn out.

Other possibilities could be a transmission input shaft seal leaking, and getting gear lube on the clutch disc.

[barcelona_r65]

Can you help me out with what the "clutch freeplay adjustment" is?
There's one of those "cable tensing wheels" like on a bicycle's brake lever adjustment ... but I've never adjusted it.
It must be one of those "screw it towards the clutch lever and loosen the cable ... screw it towards the cable and you tighten it .... is that what you're refering to?

This sounds like something that I could try as an inexpensive adjustment that might just do the trick ... ay?

Along the lines of mileage ... well ... hmmmm ... it's got a whole "pantload" of mileage (kilometrage over here) I'm not sure exaclty how much, I had to change the speedometer that houses the mileage counter so I've lost track ... however the motor is in great shape. Between oil changes it burns ZERO oil.  If there's a leak, there's no visual evidence of it .... the bike is in overall great condition.

[Bob_Roller]

That's pretty much the adjustment at the clutch lever, if you have the 2-3 mm freeplay at the lever, then adjustment probably isn't your problem.

There is another adjustment at the clutch arm at the back of the transmission, but like I said , with alot of kilometers on the bike, it probably is worn out more than misadjusted.

[steve hawkins]

Clutch slip usually means that the revs are rising but the bike is not going any faster under hard acceleration.  Does not usually start at low revs but often when you are trying to put max power through the clutch - when accelerating hard through the gears to get to the magic 100mph!

The only noises usually associated with this is the fact that the engine revs are going up suddenly when it lets go.  Mileage is important as as well as a worn out clutch you could have a leaking rear main seal or the O ring on the flywheel, which could be putting oil on the clutch.  Either was it is a new clutch.  But you should check for oil impregnation - and it does not have to be a lot.

If all you are getting is a funny noise then would try to local where it is.  After a 3 year layup - have you regreased your splines?

Oh and treat yourself to a new battery.

Steve H

[barcelona_r65]

So ... let me try to clear it up a bit....

The sound is more like a ringing ... or I would even say it's like the sound that you can make when you run your finger around a wine glass ... of course only much louder ... It normally only lasts from the point of releasing the clutch from a dead stop and almost only in shifting into 2nd ... and only until the bike's speed reaches what seems to coincide with its RPM's (maybe 2 or 3 seconds)  ... that is, at the beginning of the gear... ( I don't know if that makes sense ...  :-/ ) ...


Here's a few things I need to shoot back at y'all:

1. How can I check for oil impregnation? Where do I look? ... Is is something I can do without opening anything up?

2. Frankly, I wasn't aware that I had any "splines" for greasing!   :-?  (i.e. What's a spline?)

3. I got past the battery problem by myself ... the replacement was the easy part.

If anyone thinks it would help, I could record a sound file (mp3) of the noise and try to attach it to my post ....


Thanks!

[Bob_Roller]

There's not much you can do, without removing the transmission and clutch disc and pressure plates, for a an inspection.

This is best left to someone that has done the job before, it's about 10-12 hours of work.

That is not factoring in any problems with rusty / siezed fasteners.

[trolle]

10-12 hours is a bit too much, I would say 4-6 hours if you do your homework first. It took me one hour the last time I did it, but then I had done it four or five times before due to my inexperience in placing the main seal with the right side out.  

The top of the flat part of the engine which goes beneath the tranny must be dry! If there is oil there the rear main seal  is probably leaking.

To give you an impression of the area look at http://picasaweb.google.com/petertrolle/BmwR6584Restoring/photo#5134857355767146066 and http://picasaweb.google.com/petertrolle/BmwR6584Restoring/photo#5134860869050394514

greetings from a dark and rainy north

trolle

[Bob_Roller]

 This time frame starts when I walk into the garage, until I'm done cleaning up and putting away all tooling as well.

I remove the whole swing arm and final drive when I do the job, so it takes me additional time.

I also clean and lube the swing arm bearings, and clean and lube the rear brake pedal pivot point while I've got it apart. As well as the final drive output splines, and the splines on the rear wheel.

I like a lot of room to work in, and nothing in my way.

The BMW flat rate labor charge to do a spline lube is 10 hours, according to the local independent BMW shop that I do business with.

[nhmaf]

This *might* be indicative of a bearing that is wearing/failing on the clutch pushrod instead of the clutch itself slipping, or possibly a worn bearing or gear in the transmission if it is only happening in first gear and only at low speeds/startup.  Usually a high whining sound in these cases on autos is related to throwout bearing failures or transmission bearings.    But, you will possibly have to inspect for possible oil leaks and examine the state of the clutch, pressure, and cover plates (and clean grease the splines !) anyhow to get to the bottom of this.

First things, first though - do the "easy" stuff, such as looking for any seeping/oil leak symptoms in the areas identified in the earlier posts.

Can you get the bike to make the sounds while running it on the centerstand in the garage ?  (you must carefully balance it so the rear tire is off the ground, keep the engine RPMs low, and ease it into first gear and slowly let out the clutch)... if you haven't done this sort of thing before, make SURE that there is no one and no valuable property in front of the bike before you start !  ;-)

[thrang]

Don't be afraid to just jump in and get yor hands dirty. Yanking the gear box and back end off an airhead sounds much more scary than it is actually is to do. I guess first time I did the clutch on mine it took ma about five or six hours but the days its no more than a couple of hours. For me the hardest part of the job is getting the bloody rubber boot back over the UJ and sitting right.

[Semper Gumby]

Hi barcelona_r65,

BEFORE you do this you must read the snowbum tech files on the the spline lube.

BTW - there are two possible sources of noise.  The first is the throwout bearing on the back of the tranny.  You can get to this without removing the tranny.  The second is the where the clutch push rod meets the center of the forward clutch plate.  This rod pushes the plates apart when you press the clutch lever.  The end of the rod has to have some grease on it or you will get a "chirrp" when releasing the clutch.  On my 1980 it happens in first and second gear.  (Yes its time for another spline lube.)

http://www.cdegroot.com/cgi-bin/mirror/pweb.jps.net/~snowbum/techindex.htm    for all the articles.

The article you need to read right now is:

http://www.cdegroot.com/cgi-bin/mirror/pweb.jps.net/~snowbum/inputsplinesthrowout.htm

Good luck and keep those questions coming.

[Ed Miller]

I don't know if that mirror site will stay up, or if it will be updated.  Snowbum has a new site here:

http://bmwmotorcycletech.info/techindex.htm

[Semper Gumby]

Thanks I will change my link.