Clutch Spline Failure Analysis

[awagnon]

I want facts.

Actually there have been well documented cases of significant axial misalignment in some of the early ( approx. 20,000 miles ) failures. Of interest, if not corrected, these splines went on to fail again, which suggests, but doesn't prove, axial misalignment probably contributes to some of the early failures. There was a very nice write up in On The Level on the engineering aspects of the spline failure with some of the cause related to the fact the transmission input shaft splines only engage about 2/3 rds of the clutch splines which places excess stress and wear on the splines if there is any misalignment. One report on the metallurgy suggested less than optimal hardness of the splines. That's the data I know about. The incidence of spline failure should be close to zero and it clearly isn't.

There is still no data showing that aggressive lubrication of the splines prevents failure. I suspect it just delays it on bikes destined to fail.

[Twempie]

I'm suddenly experiencing loud and clunky downshifting, and frequently missing second gear from first (this started a few weeks ago). My research led me to here. I've read most of this thread and apologize in advance if these questions have been answered.

Along with the clunky downshifting and frequently missing the upshift from first to second, I've noticed a chatter when I pull in the clutch-lever (2003 R1150R, just over 28k, second owner, I've had the bike almost a year). The chatter is not overly loud, but it's definitely there. The system is due to be bled and that's the first step I intend to take.

I was wondering if this clutch-lever chattering was a sign the splines were ready to fail?

I read that a fix costs about 2-Large. If this work needs to get done, is the replacement spline-setup reliable, or the same junk that could also fail? (Which would be an admission by BMW that the original splines were inadequate.)

[Just-Beeming]

I had absolutely no sign my splines were about to fail. No clunk, no slipping, no whirring, NOTHING....
I was aprox 55 mph on a slight downhill. When I increased throttle for slight uphill...all hell broke loose.
No power to the wheel.... Sounded like a tin can full of wildcats. I pulled clutch in to shift and it made the sound of beans spinning in a tin can...let the clutch out and it sounded like wildcats again. Screaming, roaring, grinding...

Riding style...I really resent this kind of speculation that riding style has anything to do with this.
I ride it.... like I have been taught to ride.
I RIDE it!
short of all out abuse... There is little that I can do to it that it should not be able to handle.

Has anyone heard....Are the RT's, GS's having this same incidence of failure?

JB

[sweatmark]

Greybeard's comment:

UNTIL such time as formal...FORMAL design and metallurgical analysis is conducted it is all amateur hyperbole and hysterical speculation.

Beating-dead-horse facts:

• Spline failures have occured on R1150R/GS/RT motorcycles. The failures appear real and attestable, based solely on what's found online, unless there's a troll working overtime on a brand-smearing hoax. Check ADV, SportTouring, and the MOA boards for references.
  
  I have a personal friend that experienced 2 such failures with his R1150RT before moving to a different brand; this acquaintance is a degreed mechanical engineer with no penchant for "hyperbole". I also have a fellow R1150R owner, Just-Beeming, who lives nearby and has reported within this thread about spline failure - that's hitting "close to home".
  
  Splined-shaft dry clutches have been used successfully in automotive application for a long time without common failures. This statement is based solely on personal observation, but such an understanding is shared by many acquaintances who are automotive mechanic professionals.

If any of these statements can be challenged, then please bring it on!

Now, as to the failure mode of BMW R1150** transmission input spline problems, I would agree that there's little "factual" information... which doesn't matter during this stage of denial by the manufacturer and its consequential lack of custoemr support.

Who's going to tackle this "FORMAL design and metallurgical analysis" if not the manufacturer? An owner with deep pockets and deeper conviction? An owner who just happens to have authoritative resources for parts failure and/or automotive drivetrain design at their disposal?

All I want right now is a remedy: parts designed by someone with drivetrain expertise that can be retrofit in our Roadsters, Rocksters, GSs, and RTs such that dry clutch transmission input spline failure rates are similar to those in auto applications, which is to say "unheard of".

[awagnon]

Has anyone heard....Are the RT's, GS's having this same incidence of failure?

There was a survey on the BMW Sport Touring forum. There was a large number of spline failures reported. The highest number was in the 2002 1150RT's (such as mine, which failed). The number of failures was less as the years increased, but the bikes were newer and may not have had time to fail. It occurred in all models, but the RT represented the greatest number.

I've never heard anyone suggest riding style has anything to do with the failures. I'm about as conservative a rider as you will find, and mine failed.

[Greybeard]

Still playing Devil's Advocate here;

Google "BMW motorcycle spline failure" you get 3,340 pages.

Google UFO's and you get 10,800,000 pages.

I want scientific proof.

[awagnon]

I want scientific proof.

Want to see a picture of my splines. They were real. It should not happen. On the way to the MOA rally in Gillette, the first two RT riders I met had prior spline failures. Do you need to be hit over the head with a stripped spline to believe it's real? At the MOA rally in Wisconsin, at one of the tech sessions, Paul Glaves asked how many in the crowd had experienced drive line failures (mainly splines and final drive failures). Around 15% held up their hands. Not very confidence inspiring.

[Greybeard]

just a feeling it must help based on anecdotal experience.

And that's my difficulty with this entire question.

UNTIL such time as formal...FORMAL design and metallurgical analysis is conducted it is all amateur hyperbole and hysterical speculation.

I've no doubt there are failures.
More failures than there should ever be.
But there are too many potentially contributing factors to the results we're seeing.

I want facts.

I'll post it again in case you missed it;

I've no doubt there are failures.
More failures than there should ever be.
But there are too many potentially contributing factors to the results we're seeing.

[awagnon]

I'll post it again in case you missed it;

I've no doubt there are failures.
More failures than there should ever be.
But there are too many potentially contributing factors to the results we're seeing.

You're absolutely correct. I'm not getting your point. This is a real problem. There is something wrong with the design, metallurgy, and/or assembly quality control that is causing the splines to fail at an unacceptable rate. BMW does not recommend periodic lubrication, so at least they don't believe there is a lubrication issue and there is no data that lubrication prevents it. The final line, the splines are failing and BMW is not fixing the problem for bikes out of warranty. This is an expensive repair which shouldn't be necessary on such as expensive bike. Even worse is when this happens on a vacation or in middle of nowhere, the cost of a spline failure increases significantly.

It sounds like you accept there are more failures than there should be. I accept the fact that we don't know the cause. I wish BMW would accept their responsibility and extend the warranty on the drive line. If there isn't a problem, then it won't cost BMW a cent to extend the warranty. If there is a problem, then they've done the right thing.

[Lobo1625]

I'm surprised this thread has picked up again from all the negativity surrounding it the first go around. As an update to an earlier post I haven't had any luck with any aftermarket clutch disk manufacturers. My current approach is to have a replacement clutch disk center section machined and properly hardened. With this part I'd have the stock clutch center section replaced with the new one. Also, as mentioned earlier the stock clutch hub is quite soft in regards to industry standards, so hardening alone will no doubt help the issue. In addition to the hardening, the new center will be longer to engage more of the shaft for greater contact area. A good clutch shop will be able to do the replacement and at that point there would be an option available to those who don't want to upgrade the input shaft.

I'm going to use my own 9,800 mile R1150R for the test mule. This week I'll be at the minimum taking the clutch out for inspection and documentation. I have not ridden the bike easy, but I am a firm believer that a motorcycle should be ridden, not coddled and babied. If BMW intended the bike to be pampered they would have put stickers all over it and warnings in the manual that full throttle would void the warranty. I'll take measurements for run-out and pictures, the same as I did on the last clutch disk replacement I helped with. I honestly don't know what to expect, when I pull the transmission off this weekend, but am certainly hoping for the best.

If anyone has information or resources that would AID in the development of a replacement clutch disk, please don't be bashful. I am making due with the help of machine shops and suppliers I deal with at work. Clutch spline mechanical data or other such info would be greatly appreciated and cut down on my research time as well. Thank you to all who have helped so far and I'll keep the community updated as best I can.

[sweatmark]

Al's got it covered with this statement:

The final line, the splines are failing and BMW is not fixing the problem for bikes out of warranty. This is an expensive repair which shouldn't be necessary on such as expensive bike. Even worse is when this happens on a vacation or in middle of nowhere, the cost of a spline failure increases significantly.

I would only add that, for a motorcycle designed with an automotive dry plate clutch, such a failure should never occur.

With the sorry expectation that R1150** owners are abandoned by BMW Motorrad with respect to this problem, how do we proceed to find cost-effective solutions? There's been some work done in failure analysis, as well as replacement parts design and testing. What's the next step towards a solution, in the form of new parts + troubleshooting + installation + maintenance?

<edit> Lobo, good to hear from you again. Posted the above at same time you gave the update. Good news about the revised clutch hub design. I will make some calls regarding transmission spline design criteria, and ask for opinions from automotive clutch service folks who must see hundreds of splined transmission input shafts each year. There must be a consensus about some of the basics: alignment measurements, spline wear patterns, lubrication.

[boxermania]

One of the major design issues with the BMW clutch is the fact that the tranny input shaft doesn't have a boss fit to the rear of the crank like all the automotive applications. This insures that the components not only remain in line, but that the angular forces on the clutch, due to its engagement are supported on both ends.

On the BMW the torque on the disk is supported by the tranny bearing alone, in essence the clutch disk and the ensuing rotational forces are cantilevered on the tranny input shaft. Add to this the metallurgy issue with the clutch disc splines, short engagement and potential misalignment and you are opening Pandora's box.

As the BMW bikes grew in displacement and HP the clutch had to endure increasingly large rotational loads within the constraints of the design envelope. Everyone knows that slipping the clutch on one of these bikes can toast the clutch in short course.

There is no question in my mind that the OEM new about this as the BMW boxer clutches have had a long history of lack of reliability in models prior to the oilheads. Add to this parts manufactured by different providers and one can see a system out of control fairly quickly.

Clutch spline failure - Potentially dangerous
Cost to repair - Expensive if done out of warranty or extremely time consuming if done by owner
Repair solves the problem - Unlikely as parts don't appear to have been re-designed
The inability of BMW Motorrad to accept product responsibility and deny the existence of a problem - PRICELESS

[bransan]

I'm surprised this thread has picked up again from all the negativity surrounding it the first go around. As an update to an earlier post I haven't had any luck with any aftermarket clutch disk manufacturers. My current approach is to have a replacement clutch disk center section machined and properly hardened. With this part I'd have the stock clutch center section replaced with the new one. Also, as mentioned earlier the stock clutch hub is quite soft in regards to industry standards, so hardening alone will no doubt help the issue. In addition to the hardening, the new center will be longer to engage more of the shaft for greater contact area. A good clutch shop will be able to do the replacement and at that point there would be an option available to those who don't want to upgrade the input shaft.

I'm going to use my own 9,800 mile R1150R for the test mule. This week I'll be at the minimum taking the clutch out for inspection and documentation. I have not ridden the bike easy, but I am a firm believer that a motorcycle should be ridden, not coddled and babied. If BMW intended the bike to be pampered they would have put stickers all over it and warnings in the manual that full throttle would void the warranty. I'll take measurements for run-out and pictures, the same as I did on the last clutch disk replacement I helped with. I honestly don't know what to expect, when I pull the transmission off this weekend, but am certainly hoping for the best.


If anyone has information or resources that would AID in the development of a replacement clutch disk, please don't be bashful. I am making due with the help of machine shops and suppliers I deal with at work. Clutch spline mechanical data or other such info would be greatly appreciated and cut down on my research time as well. Thank you to all who have helped so far and I'll keep the community updated as best I can.

I had mine apart this last winter, @ 27k mi, I saw only minimal wear. The input shaft was a little shiny wear the clutch disk spline rides. There was noticeable wear on the input shaft. I don't consider it excessive wear, considering I am pulling a Uni-Go trailer most of the time. I will be pulling it apart again this winter. After taking it apart the first time I realized how easy it is to lube the spline shaft. A note to everyone; buy the tools and take the time to perform this maintenance. Be sure to use the BMW spline lube, I found it at Moon motors in Monticello, Mn. Cheap too!

[iowabeakster]

bransan,

The input shaft isn't the part that is causing all this grief. It's the splines inside the cluch hub that are wearing out and failing.

Did you remove the clutch disk and clean out the old grease to inpsect it's splines? I thought that one needed to pull the whole tranny and driveline rear of the engine to get the cluch disk out.

[Lobo1625]

bransan,

The input shaft isn't the part that is causing all this grief. It's the splines inside the cluch hub that are wearing out and failing.

Did you remove the clutch disk and clean out the old grease to inpsect it's splines? I thought that one needed to pull the whole tranny and driveline rear of the engine to get the cluch disk out.

You are mostly correct in your statement. The input shaft is causing problems partially because it is too short. The splines inside the clutch disk itself are what gives away and wears out first, causing wear on the corresponding areas of the input shaft.

To get the clutch disk out, you do have to pull the transmission and driveline off the bike. I anticipate a 5 hour clutch replacement job this week (hopefully tomorrow if parts come in) with 2 people. The hardest part is learning what needs to come off, be unbolted and what doesn't. I've seen a good photo-documentation on how to do it, but can't at this time recall where i saw it.

[sweatmark]

Lobo- Is this the clutch/spline pictorial you're referencing?
http://www.bmwbmw.org/bmwforums/viewtopic.php?t=10801

[Lobo1625]

That's the one, but they show removing the rear wheel, then the telelever/driveshaft and then then the transmission. Last bike we did, we left the rear tire on and rolled it away from the bike as one whole transmission/telelever/wheel assembly. It's a bit ungainly so two people make it much easier to maneuver without dropping.

[iowabeakster]

It's a bit ungainly so two people make it much easier to maneuver without dropping.

It's the (skillful) reattachment of that ungainly piece that worrries me most about this little service. I thought bleeding the ABS was a hassle.

[ncator]

Thanks for all the great info on this menace to our fine machines. Unfortunately I experienced this failure 2 months ago with my 02' 1150r w/ 22k miles. NOT a pleasant experience nor cheap. Total cost $2,500 to repair. Bike in shop for one month which is another story altogether of bmw of Salt Lake's atrocious customer service in their service dept. Suffice to say I will NEVER take my bike to that shop again. Excuse the rant. Bottom line is that our fine machines are suseptable to this failure. The mech I spoke with (who rides a 1150r) said the ONLY WAY this could have occurred is from USER abuse. Meaning someone attempted many brake starts, clutch pops and wheely attempts. I cannot discount this as I am not the original owner but from these threads posted it appears that the problem is otherwise.
At least I'm back on the bike and enjoying the summer and Nat'l Rally. Much appreciation to all of you who provide excellent, intelligent and humorous info related to our bikes.
Cheers and ride safe & often.

[Just-Beeming]

User Abuse is a scapegoat answer....its bunk!