A "Real" Spline failure

[matanuska]

This post is about a problem on my newly acquired K Bike, but there has been so much talk about spline failure on Oilheads as well that I figure this would be the appropriate place for the discussion.

 

Last Wednesday, I was riding home from the store on my “new” ’00 K1200RS (owned for 2 ½ weeks – bought with 32k miles on the odometer). I was coming out of a right turn, gave the throttle a little gas (definitely not gunning it) and heard a ZZZIIIPPPP!!!! I was able to pull over on a quiet side street and found that I could race the engine with no power transfer to the rear wheel in any gear!

 

After shutting down, locking up, and a 3 mile walk home, I called Jerry on the phone and we discussed several possible failure modes, but the most likely seemed to be the dreaded SPLINE FAILURE!

 

On Thursday, I took the day off work, rented a trailer, towed the bike home and started the long disassembly process. Last night, I finally removed the tranny and disassembled the clutch. The clutch plate spline is shot! Interestingly, the matching external splines on the trans input shaft don’t look all that bad and could probably be reused in an emergency (see pictures), but the excess clearances would likely lead to an early failure again. I checked the parts fiche and a new transmission input shaft is not all that expensive ($228) and it would make sense to replace it as long as everything is apart. I’m also going to replace the engine rear seal as well, although it really wasn’t leaking too badly.

 

I’ve been looking over the procedure for installing a new transmission input shaft and while not terribly complicated, it does involve a few special tools for measuring and calculating shim thickness (assembled shaft length tolerances is .002”), as well as special seal installation tools. While this might be a job possible for the home mechanic, having the correct know-how would certainly be a benefit. I would hate to reassemble everything only to have a leaking transmission oil seal due to incorrect installation. I’m almost thinking about calling up a dealer and asking how much they would charge if I dropped off the tranny with them.

 

So what do you guys think?

Replace the transmission input shaft myself?

Bite the bullet and pay a dealer to do it?

Leave it alone and reuse the shaft as is?

 

I can think of advantages and disadvantages to each choice (particularly economic), but in the end I’m ultimately concerned with reliability of the repair.

 

 

 

 

 

Here are links to large versions of the pictures:

Clutch & Tranny

Trans input shaft splines

Clutch plate splines

Clutch plate splines

 

Thanks

 

Derek

 

Ps. On my old R 850R, I recently suffered the almost unheard of Motronic failure. Now on my new K bike I just suffered the equally elusive (but frequently talked about) spline failure. Are the Motorcycle Gods trying to tell me something?

[Tony_K]

Having lived with old Volkswagens my entire adult driving life we have seen a lot of the same failures too. Usually at the axel to wheel drum juncture.

 

The trans shaft is of a better steel grade than the disc by design so that the lesser fails first.

 

Go ahead and purchase a new disc plate clean your trans splines well and fit the new disc on. If there is no slop or play you will be ok!

 

Give it a shot there is hope then get out and ride.

[bmweerman]

First of all...Damn that sucks !!!

 

2nd get it repaired and ride...what are the chances of it happening 2x in a row.

 

Still you have my sympathies bro!!!

 

Keep us posted!!!

[Boffin]

Have you checked out the price and availability of a rebuilt gearbox? This could be a more cost effective solution.

 

Andy

[Tony_K]

In addition reviwing the larger photos better since I can't see it well. closely inspect your trans spline. Do you see or feel a ridge anywhere along the splines? I would say no after studing the photo.

 

Now if you had inspected your disc before the total failure you would have seen a very noticable "C" notch all the way around the interior splines.

 

I have this problem on my /2 at the final drive on the wheel. I could feel it in the wheel on the center stand moving it back and forth. Took it off and yup notched!

[matanuska]

In addition reviwing the larger photos better since I can't see it well. closely inspect your trans spline. Do you see or feel a ridge anywhere along the splines? I would say no after studing the photo.

 

Unfortunately, yes, there is a slight groove worn into the input shaft splines. It's really hard to see in the photos, but can be felt. That's why I'm hesitant about reusing the shaft. I'll see if I can find a better photo.

 

DR

[matanuska]

This shows the wear a little better:

 

Larger Image

[Bruce C]

You have access to about 5-6 BMW dealers within a 1 hour drive.

I would call around for a rebuild price. You might be shocked, but at least you would know the cost.

And also ask about a warranty on the trans. work if you install it.

 

Bruce C

[Dennis Andress]

I had more than a few spline failures in my airhead days. And, I've lubed the splines on three different K100's. Those splines look ugly! There's cupping near the rear of the shaft and splines seem to be polished and rounded. I say replace the shaft.

 

Would you show more pictures of the jig you made to hold the bike and give a description of how it came apart? My clutch is slipping and it sure would be nice to have some preparation.

 

Dennis

[matanuska]

I had more than a few spline failures in my airhead days. And, I've lubed the splines on three different K100's. Those splines look ugly! There's cupping near the rear of the shaft and splines seem to be polished and rounded. I say replace the shaft.

 

Would you show more pictures of the jig you made to hold the bike and give a description of how it came apart? My clutch is slipping and it sure would be nice to have some preparation.

 

Dennis

 

I'm making an extensive photographic journal. I'll try to have some photos up on a website soon.

 

DR

[John95KLT]

I just joined this group not five minutes ago and the first thing I come across is your post. First sorry to hear about this on a fairly new and low mile machine. But you do have to have it repaired. My opinion is that if you are capable of disassembling the bike to find the damage you are just as capable of installing the trans shaft too! I'm a former ASE tech now in engineering and I still do all of my own repair work. My 95 K11LT is down for some repairs including removal of the final drive for a spline inspection. Now that I've read your post I wonder if I should check the clutch splines while I'm at it. But that's my problem not yours. If you do decide to jump into the trans please stay in touch. I don't have the service manual for your bike but if I can offer any assistance I would be happy do so. Good luck!

[bmwmick]

I'd say do the input shaft yourself. The manual covers it petty thoroughly and if all you are doing it replacing the input shaft, the end clearances should not change.

Your input shaft looks a LOT like the K75 and K1100 bikes I've seen with bad intermediate housings. They also look a LOT like the Oilhead failure where the friction disc is wobbling just enough to tear that gouge out of the input shaft splines.

This is an alignment failure NOT a lack of lubrication failure. My K1100 came apart at 125K miles for a new friction disc (because it was wet with oil, not worn out) and my clutch and input shaft splines looked like new.

 

Mick

[Bruce C]

Derek

On one of the other sites you answered a post by stating that you also experienced a lot of trouble downshifting before the clutch blew out. How long was this a problem? How was it upshifting? Did you drain the gearbox yet? Anything in it?

Can you give a another report on when and how this started? I was just thinking of a list of symptoms that led up to the failure.

 

Dennis

When is your clutch slipping and for how long before it locks up? Or will it slip whenever you get on it?

 

Bruce C

[John Moylan]

Last Wednesday, I was riding home from the store on my “new” ’00 K1200RS (owned for 2 ½ weeks – bought with 32k miles on the odometer

 

...surely if you've only had it 2.5 weeks, then it's covered under warranty by the shop?

[matanuska]

Last Wednesday, I was riding home from the store on my “new” ’00 K1200RS (owned for 2 ½ weeks – bought with 32k miles on the odometer

 

...surely if you've only had it 2.5 weeks, then it's covered under warranty by the shop?

 

I bought it from another member on this board. No warranty available!

[matanuska]

I'd say do the input shaft yourself. The manual covers it petty thoroughly and if all you are doing it replacing the input shaft, the end clearances should not change.

Your input shaft looks a LOT like the K75 and K1100 bikes I've seen with bad intermediate housings. They also look a LOT like the Oilhead failure where the friction disc is wobbling just enough to tear that gouge out of the input shaft splines.

This is an alignment failure NOT a lack of lubrication failure. My K1100 came apart at 125K miles for a new friction disc (because it was wet with oil, not worn out) and my clutch and input shaft splines looked like new.

 

Mick

 

Mick, a member on another board commented on how small this spline shaft was considering the 137hp output of the K1200 engine. I agree, particularly when you comapre it to the engine/clutch spline and the driveshaft splines.

 

If this is an alignment problem, what's the fix? Jerry and I were discussing this too. The clutch palte is almost, in a sense, a floating disc so it should almost self align?

 

DR

[matanuska]

I just joined this group not five minutes ago and the first thing I come across is your post. First sorry to hear about this on a fairly new and low mile machine. But you do have to have it repaired. My opinion is that if you are capable of disassembling the bike to find the damage you are just as capable of installing the trans shaft too! I'm a former ASE tech now in engineering and I still do all of my own repair work. My 95 K11LT is down for some repairs including removal of the final drive for a spline inspection. Now that I've read your post I wonder if I should check the clutch splines while I'm at it. But that's my problem not yours. If you do decide to jump into the trans please stay in touch. I don't have the service manual for your bike but if I can offer any assistance I would be happy do so. Good luck!

 

John thanks for the offer, I might take you up on it!

 

I was thinking about this and as long as the new shaft has the same dimensions, the original shims will give me the same overall length. I'm sure I can rig up some kind of fixture for verifying this dimension.

 

It also sounds like the shaft bearings are pressed into the housing as the manual talks about heating to 80 - 100C to remove the bearings.

 

I'm probably more concerned about installing the seals correctly. The manual shows pictures of custom mandrels/drifts for each seal. I might just make a set of my own.

 

Thanks again

 

DR

[matanuska]

Derek

On one of the other sites you answered a post by stating that you also experienced a lot of trouble downshifting before the clutch blew out. How long was this a problem? How was it upshifting? Did you drain the gearbox yet? Anything in it?

Can you give a another report on when and how this started? I was just thinking of a list of symptoms that led up to the failure.

 

Dennis

When is your clutch slipping and for how long before it locks up? Or will it slip whenever you get on it?

 

Bruce C

 

 

The problem was somewhat evident since I bought the bike and the previous owner noticed it the whole time he owned it too (approx 4 months). I guess we both just figured "that's the way it is". However, the force required for downshifting suddenly increased, very noticably, about 3 days before the failure.

 

Upshifting was no problem at all, though I did sometimes have problems missing the shift from first to second.

 

Clutch never slipped.

 

Oil from the tranny was VERY cloudy compared to the final dive oil which was crystal clear (both appeared to have synthetic oil).

 

Nothing much to speak of on the drain plug magnet. Only a few filings, but nothing more than I would get on my old R 850.

 

I am definitely interested to get a look inside the tranny.

[Dennis Andress]

I was thinking about this and as long as the new shaft has the same dimensions, the original shims will give me the same overall length. I'm sure I can rig up some kind of fixture for verifying this dimension.

 

When I was an official hanger-on at Iron Horse years ago they once said that most trannys go back together with the original shims.

 

It also sounds like the shaft bearings are pressed into the housing as the manual talks about heating to 80 - 100C to remove the bearings.

 

I remember they used a hot plate and heated the bearing for at least an hour. Then they dropped it on the input shaft. After that, they heated the housing with a heat gun and installed the shaft and bearing

[Dennis Andress]

Dennis

When is your clutch slipping and for how long before it locks up? Or will it slip whenever you get on it?

 

The clutch slips while it's engaging. For instance, a 4th to 5th shift under throttle whil cause it to slip while it slowly engages, say maybe 3 seconds. Getting on it hard from a stop is really bad

 

I have a small oil leak which seams to be coming from around the starter. I don't think that oil is reaching the clutch but the bike has an extended waranty so it would be really nice if that were the case.

 

I think I'll have the whole mess looked at sometime after Torrey.

[Bruce C]

Yes, it would be nice if that leak grew larger just as you got back from Utah.

 

Bruce C

[nrp]

If this is an alignment problem, what's the fix? Jerry and I were discussing this too. The clutch palte is almost, in a sense, a floating disc so it should almost self align?

 

The clutch plate only floating when the clutch lever is pulled in. When the clutch is engaged (handle out), the disk is force to rotate around the axis of the crankshaft, and the input spline around the axis of the transmission. There is very possibly some error between those two axes.

 

Assuming you do tear the transmission down, you should check the runout between the tranmission input bearing bore, and the crankshaft rotating axis. There is a lot on ways to do this under the Oilhead posts.

[matanuska]

I was thinking about this too over dinner. My plan would be something like:

 

First make up a test bar for the clutch housing and check the squareness of the clutch surfaces to the shaft bore.

 

Then mount the clutch on the engine and check the parrallesim of the clutch surfaces to the rear flange of the bell housing.

 

Then do something similar for the tranny. Make a test bar and check the squareness of the shaft to the front mounting flange and check the squareness of the new clutch plate to it's shaft bore.

 

Finally mount the tranny to the engine and check the concentricity of the two shaft axes.

 

I wonder if there is any way to get the official BMW tolerances for any of these.

 

Derek

[Dennis Andress]

I was thinking about this too over dinner. My plan would be something like:

 

First make up a test bar for the clutch housing and check the squareness of the clutch surfaces to the shaft bore.

 

Then mount the clutch on the engine and check the parrallesim of the clutch surfaces to the rear flange of the bell housing.

 

Then do something similar for the tranny. Make a test bar and check the squareness of the shaft to the front mounting flange and check the squareness of the new clutch plate to it's shaft bore.

 

Finally mount the tranny to the engine and check the concentricity of the two shaft axes.

 

I wonder if there is any way to get the official BMW tolerances for any of these.

 

Derek

 

 

 

Wow! I'm just a simple electronics guy who learned to write software and changed careers, but while I can understand all of that I'm really envious of someone who can make it happen.

 

And, I have a story that may shed a different light on all of this. Years ago when I was stationed in Frankfurt I built an airhead from parts (Well, I built three after a couple buddies wanted their own...) A year later when my bike and I were back in the states the clutch splines failed. Then they failed again within a year. And again.... Thinking that I'd matted a tranny and engine together that didn't match, I went through the the same thoughts as ya'll are having here. But it didn't make sense, why would BMW make a change in something like these mating surfaces? They didn't obviously. Then I figured out that I'd used the wrong clutch plate and it's splines didn't fit tight enough on the input shaft.

 

Try measuring from the center of each shaft to each of the locating pins on the monting flanges. Then assembling the clutch and doing the same to the center of clutch plate. Turning the crankshaft and measuring to the clutch plate again would be interesting. And, with just the flex plate mounted to the crankshaft and a bar across the matting flange you could measure from the outer edge of the flex plate to the bar, again turning the crank...

 

Similar to my dilemma years ago, the alignment of the tranny on the engine has way more thought and QC put into it than the squareness of the assembled clutch. Look at it this way, if the splines had failed a period of time after a mechanic you didn't know had worked on it would you still be looking for an alignment error or would you checking his workmanship?

 

Dennis

[John95KLT]

Derek,

 

I agree with Dennis in that we have to have faith that the engineers know what they are doing and the mating surfaces of the engine and trans do align correctly so I would not spend much time trying to make sure that they are true. I have seen this type of spline failure on driveshafts used in a completely different industry but the appearance is identical. As near as we can determine the spline failure was due to extreme stress on the splines that once they started to wear premature failure was inevitable. We remedied this by applying moly grease to the splines. However, during my automotive years, we only applied a "very light" coat of white lithium grease to the input shaft splines just to make sure that the clutch disk would move freely on the shaft splines. You must not allow grease to contact the clutch lining. If the disk hangs on the shaft, the clutch disk will continue to contact the flywheel surface when the clutch is operated. I suspect that this is the reason that your bike was hard to shift just before the complete failure. I'm certain that with the new trans shaft, clutch disk and the correct (and very light application) lubricant on the splines, you will not have this type of failure again.

[matanuska]

Dennis,

 

That actually makes allot of sense. Before going off and measuring the squareness of every mounting surface to the Universe down to +/- 0.0001", best to check the simple stuff first, like did they use a bad/wrong/poorly fitting clutch plate. Like you said, it would have to be a pretty big failure of BMW QC to miss some kind of misalignment between the motor and tranny. This would also be hard to overlook as the pushrod runs from the back of the tranny, through the center of the input shaft, clutch, and into the engine output shaft. Any misalignment in one of those components would make smooth clutch actuation problematic.

 

From one of the other boards, I've learned that BMW made a change to the OEM part spec for the clutch plate sometime during the later life of the K12RS production run. I checked, and I have the old part number clutch plate.

 

It may be possible that some kind of recall or service notice went out on these old clutch plates. If so, it may also be possible that some of this might be covered under some kind of warranty. Looks like I have some more research to do at the BMW dealer.

 

DR

[matanuska]

Derek,

 

I agree with Dennis in that we have to have faith that the engineers know what they are doing and the mating surfaces of the engine and trans do align correctly so I would not spend much time trying to make sure that they are true. I have seen this type of spline failure on driveshafts used in a completely different industry but the appearance is identical. As near as we can determine the spline failure was due to extreme stress on the splines that once they started to wear premature failure was inevitable. We remedied this by applying moly grease to the splines. However, during my automotive years, we only applied a "very light" coat of white lithium grease to the input shaft splines just to make sure that the clutch disk would move freely on the shaft splines. You must not allow grease to contact the clutch lining. If the disk hangs on the shaft, the clutch disk will continue to contact the flywheel surface when the clutch is operated. I suspect that this is the reason that your bike was hard to shift just before the complete failure. I'm certain that with the new trans shaft, clutch disk and the correct (and very light application) lubricant on the splines, you will not have this type of failure again.

 

John,

 

We're definitely on the same page there as well. I'll be sure to ask what kind of grease BMW uses for splines. The splines on the front and rear of the driveshaft were well greased, and the engine spline is at least partially lubricated by engine oil. However, the clutch spline was dry as a bone.

 

DR

[Dennis Andress]

As near as we can determine the spline failure was due to extreme stress on the splines that once they started to wear premature failure was inevitable. We remedied this by applying moly grease to the splines.

 

John,

 

There is almost a cultish religion regarding what grease to use on clutch splines. No one uses BMW's product.

 

 

As I'm sitting here listening to Gov't Mule it dawned on me that we are looking at uneven wear on the input shaft and assuming (that stuff has caused me a lot of grieve this month) that something is out of align. Reality check, everything is where it is supposed to be; the clutch plate is distorting under load. It has to. And, that little splined coupling has to change it's axis when the plate distorts.

 

Like John said, grease is the answer. I have a tube of some really thick stuff Volvo included with the CV joint repair kit. It looks like just what's needed.

 

Dennis

[nrp]

Your spline failure looks a lot like excessive radial force being transmitted across the spline. If so, this might be caused by the clutch and the transmission input shaft diagreeing on the axes of rotation such that the clutch is continuously dragged around the flywheel.

 

I have not seen the clutch disk spline center, but from the wear pattern it appears as though the spline is not longitudinally centered around the clutch disk. This is what might cause the input spline to wear more immediately adjacent to the transmission.

 

If you take the transmission apart, I still suggest you look for the possibility of an alignment problem using a dial indicator attached to the crankshaft. I wrote this up for the Oilhead group at

 

http://bmwsporttouring.com/ubbthreads/sh...true#Post636421

[matanuska]

I took my offending clutch plate in to work today for some show and tell. At work, we are fortunate to have one of the most knowledgeable and distinguished Metallurgists West of the Mississippi heading up our Materials Failure Analysis Program. Myself and another Engineer friend (Jerry) ran into him in the hall and we showed him the plate. He eagerly put it under his microscope and gave us his expert opinion. He confidently concluded that the failure mode was most likely too soft a material, coupled with an original oversize manufacturing tolerance allowing excess shock loading which over time, destroyed the splines. He felt that this DEFINITELY was NOT an alignment issue, the wear and deformation patterns were too even. A misalignment would have produced an easily identifiable asymmetric wear pattern on the splines from front to back.

 

This seems to fit with the fact that BMW changed the part spec for this clutch disc at some time in the past. Maybe the old design had too much clearance in the splines which could lead to problems. I am eager to hear what insight the service department at the BMW dealer has to offer tomorrow.

 

I am also relieved to hear that alignment was not a likely problem. I spent a few hours last night reading over all of the spline problem posts on the oilhead board and I was busy mentally designing of all sorts of tools and fixtures I could make to check the runout of my trans shaft relative to the engine. Then I realized that the K transmission is a completely different design from the R. Take a look at the drawing of the K tranny. Notice where the front cover bolts on to the housing (inside front end of the casing - its shown off in the second drawing). Now, with the cover either on or off, what happens when you bolt the tranny casing to the engine to do an alignment check. BINGO...you no longer have any access to the interior of the casing! Kind of hard to take measurements that way!!!

 

 

 

[nrp]

I too hope your metallurgist is correct in his assessment. Six weeks ago I got a new 2005 K1200LT. Be sure to use hi-moly grease on the splines on assembly. I agree that transmission front cover probably closes off access for reading any runout measurements. I wonder why the input shaft is so worn? - and it looked to me like the wear is concentrated near the transmission.

[matanuska]

I too hope your metallurgist is correct in his assessment. Six weeks ago I got a new 2005 K1200LT. Be sure to use hi-moly grease on the splines on assembly. I agree that transmission front cover probably closes off access for reading any runout measurements. I wonder why the input shaft is so worn? - and it looked to me like the wear is concentrated near the transmission.

Well, I think I would trust his assessment more than any BMW Tech. As for the wear pattern on the shaft, he believes it would have occurred as the splines got looser over time allowing the clutch plate to wobble, hammering more and more on the shaft. I think the key is, and the photos don’t show it very well, that even the wear on the shaft is uniform around the entire circumference of the splines.

 

I’m still going to do some kind of check to verify alignment during reassembly, if nothing but for my peace of mind.

[Dennis Andress]

Interesting.... Could you ask him for me about the effects the clutch plate distorting? I'm curious largely because every worn input shaft I've ever seen looks almost exactly like yours.

 

And another idea...

 

Machine a straight dowel approximately the size of the clutch pushrod, only longer and with an interferance fit where the pushrod fits into the crankshaft. Disassemble the transmission and then with this dowel stuck in the back of the crankshaft - and perpendicular to the surface where the flex plate bolts - bolt the empty transmission housing onto the back of the engine. The dowel should be sticking out the back of the transmission and centered that little hole.

[John95KLT]

Dennis and Derek,

 

This is a great idea! Simple and easy enough to confirm if the shaft is centered in the gear case housing. Good enough to satisfy the biggest worry wort. Derek, please keep us posted on the progress and results of the repair. I intend to drop my trans tomorrow night for a clutch and spline inspection. I'll share the results if you are interested.

[nrp]

The wear on the transmission input spline will be identical all around the circumference if there is a misalignment. What concerns me is that there appears to be an axial variation in wear that could only come from a fixed vector locked-in side load (i. e. shear load) during all rotation, caused by a difference in rotating centers, combined with shaft deflection. In a corectly functioning spline, the tooth loads (torque) will shift to unworn teeth. Or did I misinterpret your post?

[matanuska]

Yes, I’ve been thinking about this and I think there are so many variables that it would be hard to make a definitive conclusion based on only one set of observations. For example, we’re not just talking about two shafts whose axes could be radially or axially misaligned. The introduction of the moveable and flexible clutch disc introduces a whole new set of dynamic variables that have the ability to change based on any number of parameters (engine load, clutch engaged/disengaged, how the clutch plate centers itself when the lever is released, slippage, vibration, etc).

 

I guess, in the end, the proof will be in the proverbial pudding when I take some hard measurements of component alignment.

 

DR

[matanuska]

...Machine a straight dowel approximately the size of the clutch pushrod, only longer and with an interferance fit where the pushrod fits into the crankshaft. Disassemble the transmission and then with this dowel stuck in the back of the crankshaft - and perpendicular to the surface where the flex plate bolts - bolt the empty transmission housing onto the back of the engine. The dowel should be sticking out the back of the transmission and centered that little hole.

 

Dennis & John,

 

This is a good idea. I was thinking about this last night and came up with a plan to take this one step further by making a type of “Go / No Go” Gauge. I measured the internal bore of the trans input shaft at 10.00mm and that of the engine output shaft at 6.00mm. My plan is to buy some 10.00mm precision ground drill rod stock and machine one end down to 6.00mm. Then, with the tranny bolted back up to the engine it will be a simple matter to determine if the two assemblies are precisely aligned. If they are not, it will also be rather straight forward (though a little tedious) to determine misalignment by machining successively smaller gauges (9.50mm, 9.00mm, 8.50mm, etc) until the gauge slips in freely. Of course, this method would be most effective at detecting radial (horizontal) misalignment of the two axes. Axial (angular) misalignment might be slightly harder to diagnose and may require a setup closer to your original plan.

 

DR

[Dennis Andress]

That'll work and is much simpler.

 

How could the idea be adapted to check the alignment of the clutch plate splines to the crankshaft?

 

Dennis

[matanuska]

How could the idea be adapted to check the alignment of the clutch plate splines to the crankshaft?

That part can actually be done on a lathe.

 

Machine a test bar the size of the minor diameter of the engine splines and mount the clutch housing. Then it would be relatively easy to use a dial indicator and check the running squareness of the three mounting flats on the clutch housing, clutch housing cover, pressure plate, and ultimately the bore of the clutch plate.

 

Could be a problem as simple as distortion (caused by overheating?) of the aluminum clutch housing throwing the entire clutch assembly into a wobble. In that case the fix would be to take a light skim cut across the three mounting flats (or replace the clutch housing altogether). Could it be that easy?

 

DR

[John95KLT]

Derek,

I fully appreciate and understand your concerns about confirming the alignment but I'm still having a difficult time believing that that the possiblity can even exist that trans and engine alignment could be out of spec. In all my years as a professional mechanic, plus all of the clutchs I've done since I've never come across this. I'm trying to imagine what other symptoms could be present such as a slight shuddering during initial clutch release or maybe input shaft bearing wear because of radial forces. Just my unsolicited opinion but I'm about as meticulous as they come to repairs and I think I would just make sure that this repair is done correctly and move on. You can always do another spline check in 10,000 miles to determine if you're heading for a repeat failure. Otherwise, reassemble, ride and enjoy!

[Dennis Andress]

Could be a problem as simple as distortion (caused by overheating?) of the aluminum clutch housing throwing the entire clutch assembly into a wobble. In that case the fix would be to take a light skim cut across the three mounting flats (or replace the clutch housing altogether). Could it be that easy?

 

I don't think there is much chance the aluminum clutch housing has gotten hot enough to distort. But, I'll wager there are a bunch of production tolorences in the clutch assembly that could be tightened up. You and I both know that your time would be better spent doing that as opposed checking the alignment of the shafts.

[matanuska]

Derek,

I fully appreciate and understand your concerns about confirming the alignment but I'm still having a difficult time believing that that the possiblity can even exist that trans and engine alignment could be out of spec. In all my years as a professional mechanic, plus all of the clutchs I've done since I've never come across this. I'm trying to imagine what other symptoms could be present such as a slight shuddering during initial clutch release or maybe input shaft bearing wear because of radial forces. Just my unsolicited opinion but I'm about as meticulous as they come to repairs and I think I would just make sure that this repair is done correctly and move on. You can always do another spline check in 10,000 miles to determine if you're heading for a repeat failure. Otherwise, reassemble, ride and enjoy!

 

John & Dennis,

 

In a way, I agree with you. I think allot has to do with my line of work (I do Root Cause Analyses in the Nuclear Power Industry) so I might be a tad obsessed with finding the ultimate “Why” as to the cause of this failure (I also enjoy the challenge of solving a puzzle such as this). The two checks I’m planning shouldn’t really take that much time (I have access to all the required machine tools) but yea, I’ll have to resist the impulse to want to go off machining and shimming components to achieve alignment within +/- 0.0001”! I’m certainly open to doing a reinspection at some point, though I wish it wasn’t such a damn PITA to take the transmission off!

 

I guess I just have a slight case of OCD (my wife can confirm this)!!!

 

DR

 

Ps. the other observation is correct. I would think if misalignment were an issue, we should also be seeing some failure of the front trans input shaft bearing.

[Dennis Andress]

(I do Root Cause Analyses in the Nuclear Power Industry) so I might be a tad obsessed with finding the ultimate “Why”

 

 

Excuse me. My bad.

 

You go right on and check every measurment imaginable.

 

 

I spent a few years working in Avionics. OCD has it's place.

 

Dennis

[matanuska]

BTW, did you see the pictures of the other spline failure in the Oilhead forum. Same wear pattern on the trans input shaft (concentrated towards the rear), just a little worse than mine. You can also see plenty of lube still on the clutch splines.

[Dennis Andress]

What's an Oilhead?

 

 

 

 

 

 

 

[ELP_JC]

I personally think you're chasing ghosts Derek. Without knowing the history of your bike (4 owners, you said??), current part having a different P/N (obviously signaling an improvement), and failures like that being rare, just slap a new one buddy.

 

If it fails again, then do all the analyses you want. That's just my opinion. Good luck.

[Bruce C]

John

Over on another site the transmission input shaft wear problem on oilheads was narrowed to the bellhousing being out of square.

 

Bruce C

[John95KLT]

Bruce,

 

Thanks for the info. I'm not ashamed to admit that I payed 16k for my 95 KLT new and I would be an extremely unhappy camper if it had a major inherent design flaw. BMW NA is not know for being overly helpful on these issues either. I guess that's what lawyers are for. It's really too bad.

[nrp]

I contend it is not a design flaw, it is a manufacturing flaw - and that can hit anytime in a production run. The potential here for an unfortunate manufacturing tolerance buildup is even greater than for the oilheads.

 

I also contend that since it is normally a non-service item, there is little that previous owners could have done to cause this.

 

MN Mech Engr (retired)

[timmr]

You know... Those funny looking ones, with can you believe, only two cylinders. They sound funny too. They surge, cough and buck. Their owners are always complaining about something. They don't seem to be a happy bunch, GS folks excepted .