Blown clutch

[mrbuck]

Just blew the 5th clutch in the R100 on the way from Burlington Sat.  This clutch as well as all the others  was installed at the BMW dealership by trained techs.  This clutch only had 5,491 miles on it.

I don't have the gearbox out so I don't know about the input shaft which was replaced along with gearbox overhaul the same number of miles ago but at a different shop...Clutch in Raleigh, gearbox in Greensboro.

So, now what?  The OEM clutch  went 69,500 miles. The second clutch only went 14K.  The third 30,815. The fourth 25,336 (in Prospect, OR!).  The fifth 5,491.

I must admit I pressed my luck on the 3rd and 4th about the spline greasing so my bad but 5,491?!?  

I do not lug or slip the clutch and seldom run the revs below 3000rpm so I don't feel I am to blame unless it is something I haven't learned in the 145,227 miles I have ridden this old beast in the past 31 years.

Anyone got any ideas where to go from here and how to get a reliable ride without clutch worries.?

[Bob_Roller]

Was the diaphragm spring, pressure ring and pressure plate replaced at any of these clutch disc replacements

[mrbuck]

I honestly don't remember, if in fact, I ever knew.  Msbuck and I worked for these dealerships when all of this work was done...1984-2004 and since the parts and labor were more or less at cost and with employee discounts there was never a need to take shortcuts.  The last clutch was done at the dealership  and was referred to by the tech as a clutch pack.

[nhmaf]

If the failure wasn't due to contamination from a leaking rear main seal or gearbox input shaft seal or pump cover seal, I can only hypothesize that either the friction disk and/or diaphragm spring was out of spec and not replaced, or maybe it wasn't properly aligned/centered when everything was buttoned back up.   I'd request that the parts be presented for inspection so you can see if there are clues as to the failure mechanism.   Do you know if the splines are damaged or is it the friction material on the disk that is gone?   Maybe you were somehow (un)lucky enough to get the one defective friction disk?

Does your R100 have, like, a turbocharger or 1500cc kit that would boost the power output way up? ;-)

[mrbuck]

Not turbo Just a stock 70hp with 145k on the clock.

I will remove the clutch myself and take the parts to the tech that installed the clutch pack.  Hopefully, the parts will tell the tale of the failure.

I will proceed and followup with details later.  I will be more diligent with the 10k service  and ride on although the old Beemer is now used only for long trips as I have 2 other bikes.

Thanks for the speculations.  When I know more I will report back.

[mrbuck]

Also, ALL of the failures in the past were the stripping out of teeth inside the clutch plate.  I can only assume the BMW shops had the proper tools to align the clutch pack.

[Luca]

Are they using a grease with a high Molybdenum Disulfide content in the dealership, such as Honda Moly60?

Just because they should use it doesn't mean they do.  Splines wear out from poor lubrication.  Moly grease also helps with the impact forces on splines.  If a moly grease was applied to your 5K clutch, it will still be there.  If not... well, you've found your problem.

[mrbuck]

Thanks, Luca. Good point.  Time will tell.

[tvrla]

Interesting you bring this up. Just a few weeks ago I spoke with a local rider who bought his GS new twenty some years ago. He's got a very similar story to yours - in the 105K on the clock he's gone through four clutches. And they've been for the same reason, except for the first one I believe, which died a normal death. We talked at length about the situation and my conclusion is improper lubing. He also didn't do the work so didn't see the parts himself.

If too much lube is applied, clutch dust collects on the grease and acts as grinding compound. Only the thinnest layer of lube is needed and it's more for sealing out moisture to prevent corrosion than friction purposes.

I'm curious what you'll find.

[mrbuck]

Indeed, very similar.  Gearbox coming out in the next few days.  I will report findings later.  Not enough grease?  Too much grease?

Aaaarrrrgggghhhh!      What's a shade tree mechanic supposed to do?!?

Thanks for the comment.

[nhmaf]

On a number of K bikes in the mid- late 90s, there were a number of premature clutch issues related to a misalignment of the gearbox, clutch and flywheel.   I cannot seem to recall the fix, except to be more careful and double check alignment when putting things back together.  Maybe someone will recall more of this.

When doing any clutch work, the  friction disk splines should be cleaned and dried, and only sticky, high moly content grease should be applied to the transmission input shaft splines, and a bit on the tip of the pushrod.   This avoids excess greasing and potential for contaminating the friction disk

[tvrla]

Sometimes the transmission didn't mate up properly to the block, but since the first clutch lived a fairly long happy life, I'd rule that one out.

The transmission case has a ridge near the outer mating edge that locks it to the engine block. The earlier /2 had alignment problems, so I've heard, but it's not a normal problem with the newer bikes.

[Luca]

Not enough grease?  Too much grease?

Aaaarrrrgggghhhh!      What's a shade tree mechanic supposed to do?!?

For proper greasing clean the splines up till you'd eat off of them, gently load up a toothbrush with your moly grease, and brush it into the splines.  Then, brush away any excess to leave a film behind.

I find the brushing across the splines fills the crevices with grease, then brushing along them coats the metal and wipes away excess.

Any excess will quickly get squeezed out of the splines and could contaminate your clutch.  All you need is a film.  When just a little of this stuff gets on your hands, it's impossible to wipe off... the idea is it will behave the same on your splines.

If the tech tells you he put moly on the clutch, ask him what kind.  Some greases are advertised as "moly grease" but they dont have nearly the appropriate content for splined joints.

[mrbuck]

The gearbox is ready to pull and I now have concerns about the gears/bearings.  In prep of the gearbox removal, I drained the gearbox and only  200cc of gear oil came out and it smelled like burned popcorn.  There should have been 800cc in the gearbox.  I thought maybe the fluid leaked from the input shaft seal but after pulling the gearbox back 1/4 inch or so nothing came out so I guess that's all that was ever put in.....?.  Who knows.

As my favorite philosopher once said, "What is, is." so the thing to do now is  to deal with "what is" and get things back in order.

Although the mileage is low, this work was done back in 2004 so it isn't reasonable to assume going back to the dealership and complaining would do me any good.

LESSON LEARNED:  No matter how many "Authorized" signs are hung or "Certified" diplomas are on the wall....ALWAYS  check behind the technician to make sure your vital lubricants are in place.

Mrbuck said that.

[nhmaf]

Oh man, so sorry to hear about this - that is a serious irritant, to say the least.   Good luck to you as you dig further in - I am hoping that damage is as minimal as possible.