Input Shaft Spline Failure Cause

[rocinante]

I know this dead horse has been beat to...death...but humor me please. I am placing this thread in this general forum because while the problem seemed to occur with early 1150 bikes, it has occurred on bikes made both before and after those bikes were manufactured.

This problem surely has a cause and BMW is not explaining that cause, presumably for reasons of liability, but those German engineers are certainly capable of doing the analysis. Let's see if we can do that without them.

1) Misalignment - Some have suggested the shafts were misaligned from the factory. This seems implausible for at least a couple of reasons. First, misalignment would require that transmission case castings were done wrong, but that would cause many other problems of various shafts and parts within the transmission and this does not seem to be the case. Also, the clutch friction disk floats when the pressure plate is released, allowing the splines to line up. At least within a few thousandths of an inch. Far less than the wear we have seen on failed splines.

2) BMW just forgets to lube splines sometimes in manufacturing - This seems implausible also. MANY vehicles with various numbers of wheels use this same basic design and spline lube is generally just not usually a thing at all.

3) Spline Metallurgy - Perhaps certain friction disk hubs were made with allows that were too hard. Perhaps some transmission input shafts were made with too-soft alloys. Or vice versa.

4) Dragging Clutches - Perhaps certain clutches were failing to fully disengage, causing pressure plates to still be dragging against flywheels and pressure plates with the clutch lever pulled. This would put stress on both friction disk and input shaft splines. Riders not engaging clutch levers fully would also do this.

5). Other?

 

[pauls1150]

While I voted "metallurgy", the poll won't let me vote twice - when I took mine apart, there was no indication of grease, moly or otherwise, just some dried red residue that "might've been" grease back on the assembly line, but was more likely fretted-off rust.

Both the input shaft and the clutch hub were worn down.
I doubt there was misalignment, as the engine's output oil seal & the tranny's input oil seal were both still fine (but R&R'd anyway) and the trans was fine inside, no re-shimming required.
I doubt also that my clutch ever failed to disengage; on the other hand, the 1150 first gear is a little taller than the 1100 first gear, so a little more slipping is necessary if fully loaded and in traffic or starting on uphill. Dunno.

Beat to death is an understatement; due to the vast number of threads on this topic, i wouldn't be at all surprised (or disappointed) if the Moderators closed this thread...

 

[jammess]

I've owned an '04 R1150RT (bought new) and presently own an absolutely like new low miles, just turned over 14K miles with every single mile put on by me, '93 R1100RSL. I think the fact that the 1150 bikes input shaft splines only partially engaged the clutch hub splines contributed to failures of these bikes greatly whereas the 1100 machines had not only a different spline design but fully engaged with the clutch hub splines. I think common sense backs up this argument. Now, it's possible and very likely that other issues only contributed to this issue like possibly misalignment but with improper spline engagement still the primary cause. I think the majority of 1150 bikes would have seen failure eventually after seeing very high mileage over 100K miles because of lack of full spline engagement and if they had no other contributing issues like misalignment. Bikes with other issues like misalignment I think are the ones that suffered failure at very low miles with some failing at around 20K miles. My theory and I'm sticking to it. The root cause being lack of total spline engagement.

 

[rocinante]

Perhaps the Moderator should close this.

In the meantime, after more reading, my appreciation for the alignment theory grew.

 

[20774]

Perhaps the Moderator should close this.

Why does it need to be closed?

 

[pglaves]

I don't think any single explanation is applicable. Looking back as far as the /5 bikes, the classic K series bikes, and the R1100 bikes it is possible to see more than one root cause. In the 1980s BMW recommended that Airhead clutch splines be cleaned and lubricated once a year. Their history of prescribed lubricants has included anti-seize, Red BMW #14 grease, Stabarugs assembly lube and others. In my opinion none of these lubricants were suitable. A good moly paste like Honda Moly 60, or a good 25 or 30 percent moly grease is what is needed.

A significant number of K75 bikes had an alignment problem where a replacement of the "auxiliary case" (clutch bellhousing) eliminated the problem.

BMW failed to specify any interval for clutch spline lubrication on the R1100 boxer bikes. But the construction of the flywheel and starter ring gear on thin steel leafs allowed a misalignment and axial runout (wobble) causing a barrel shaped input shaft wear. With a proper moly grease every 40,000 or 50,000 miles and proper care not to bend the flywheel these splines last a very long time - in excess of 100,000 miles.

And of course the incomplete engagement of the hub and shaft on the R1150 6 speed bikes is a known engineering boo boo. After market clutch disks with extended hubs cure, along with proper installation and lubrication, solve this problem. I sold my R1150R at 189,000 miles with the original input shaft in place and one OEM clutch disk replacement, even with the short hub engagement.

 

[globalrider]

At what point in miles or kilometers do these input shaft splines fail?

 

[pauls1150]

Mine was showing sloppy shifting at about 75,000 miles, and got bad enough that I decided to break it open at about 85,000. The wear was instantly obvious.

 

[jammess]

I don't think any single explanation is applicable. Looking back as far as the /5 bikes, the classic K series bikes, and the R1100 bikes it is possible to see more than one root cause. In the 1980s BMW recommended that Airhead clutch splines be cleaned and lubricated once a year. Their history of prescribed lubricants has included anti-seize, Red BMW #14 grease, Stabarugs assembly lube and others. In my opinion none of these lubricants were suitable. A good moly paste like Honda Moly 60, or a good 25 or 30 percent moly grease is what is needed.

A significant number of K75 bikes had an alignment problem where a replacement of the "auxiliary case" (clutch bellhousing) eliminated the problem.

BMW failed to specify any interval for clutch spline lubrication on the R1100 boxer bikes. But the construction of the flywheel and starter ring gear on thin steel leafs allowed a misalignment and axial runout (wobble) causing a barrel shaped input shaft wear. With a proper moly grease every 40,000 or 50,000 miles and proper care not to bend the flywheel these splines last a very long time - in excess of 100,000 miles.

And of course the incomplete engagement of the hub and shaft on the R1150 6 speed bikes is a known engineering boo boo. After market clutch disks with extended hubs cure, along with proper installation and lubrication, solve this problem. I sold my R1150R at 189,000 miles with the original input shaft in place and one OEM clutch disk replacement, even with the short hub engagement.

Hi Paul, I agree 100% withy your choice of spline lube. When I acquired my R1100RSL with zero miles the first thing I did before even attempting to start it was to lube the input shaft splines with Honda moly lube. Then I attempted a start up and discovered the fuel pump frozen and fuel filter so clogged with fuel that had long turned to nasty smelling varnish.

 

[Omega Man]

I have found any sliding shaft, especially those with splines need lubrication. Without lubrication, the shafts generally move to “fretting” and micro wearing of the splines. When the lubrication is gone, the rust/corrosion starts. The rust particles become almost valve grinding compound and things head downhill.
The next time one walks by a large, 6-wheel delivery van/truck, have a look at the driveshaft setup. The shafts being so long there is a center support bearing and in that area you will see the sliding, splined u-joint yoke- with a grease fitting on it.

I don’t think that including a service interval to drop the driveshaft and lube the splines would be a sales feature.

To be fair, I think it would be hard to set an interval due to mileage, environmental storage and age as these are all a factor in the wear of the shaft splines…….and, a connection point (hub) a bit short.

OM