Spline Lube and Clutch Questions

[pfb]

I have the transmission off and below are the photos of the trans input splines and

the splines on the clutch side. Both are before cleaning. The area is pretty dry

So I’m glad I decided to do this. Trouble on the down shift was my impetus.

Now that it is all apart I figured I should at least check the clutch. The bike is a

2002 R1150R with 43k miles on it with no other previous symptoms. Never having

done this before I would like to make sure I’ve covered all the bases.

 

 

 

 

So here are my questions:

 

Clutch slave cylinder – upon removal about half a teaspoon of fluid ran out

Of the cavity in the trans. The end of the slave by the snap ring had a

Minimal amount crud buildup. Disassembly of the slave found the bore

Smooth and the gasket on the puck undamaged. Reassemble unit(after finding spring)

And set aside. Felt gasket thing on clutch rod slid out of trans easily and does not

Look swollen or damaged.

 

Question: is that amount of brake fluid enough reason to replace the slave cylinder ?

And if possible – is there a rebuild kit or do I have to buy the whole unit?

 

 

Trans input splines: They look like they are in good shape based on other photos I’ve seen but I can't be sure.

Questions:

1) How do the splines look?

2)Is the oil/grease buildup around the trans splines anything to worry about or

could that be The remnants of the original spline lube at the factory?.

 

 

Clutch - I’m looking at it and trying to figure out if I should check or change it or

Leave it alone.

 

Questions:

1) If I take it apart to measure the plate what thickness am I looking for.

2) If I remove the 6 bolts to check it can/should I use the old bolts or get 6

New ones recommended for a new clutch

3) Do the splines on the clutch look ok or should I replace the clutch solely based

On their condition?

 

One last thing- How much moly60 should be used

 

Thanks

Peter

[Stan Walker]

I hate to be mean but.......

 

Your input shaft splines are about 50% gone.

 

Your clutch disc is ready to fail at any moment.

 

Here is what my '02 looked like at 70,000 miles.

 

 

 

I would replace them both if it were my bike.

 

Stan

[smiller]

Hate to say this but I'd have to agree with Stan's assessment, you're going to be spending a bit more money here than you had planned. You might want to check your engine/transmission alignment as well (there are a couple of threads on the subject that you can research here) as you shouldn't be seeing that kind of damage at only 43k miles. In fact you should never see it if everything is normal.

[Stan Walker]

Your other questions.

 

Clutch slave cylinder If you are sure it's brake fluid, replace it (no rebuild kit). If it was tranny fluid, replace the seal in the transmission.

 

Clutch New bolts. Clutch wear limit is 4.8 mm. BUT your splines are shot, replace it.

 

Moly60 A light coating (I used a tooth brush for this). More will just get thrown off.

Also use it sparingly on all the parts of the clutch disc that slide (I applied it with a toothpick here).

 

Stan

[T__]

I have the transmission off and below are the photos of the trans input splines and

the splines on the clutch side. Both are before cleaning. The area is pretty dry

So I’m glad I decided to do this. Trouble on the down shift was my impetus.

Now that it is all apart I figured I should at least check the clutch. The bike is a

2002 R1150R with 43k miles on it with no other previous symptoms. Never having

done this before I would like to make sure I’ve covered all the bases.

 

 

 

 

PFB, you just posted a fine example of a BMW with impending clutch spline failure.. Not many pictures of clutch spline wear at this stage.. Usually only posted after completely stripped out..

 

You don’t have a cheap repair coming up (the posts above reflect the extent of the repair)

 

The problem is: the trans splines have significant wear showing,, especially a taper type wear that is difficult to deal with.. The clutch disk itself is close to stripping..

 

The trans spline issue is a big problem as they aren’t completely worn out yet so could have some life left in them yet _BUT you definitely need a new clutch disk.. Problem is you can’t install a new clutch disk on those worn input shaft splines as the spline to spline mismatch will quickly wear your new clutch disk & the debris created & the taper wear issue will quickly wear the input shaft more & will quickly wear you new clutch disk to the point of stripping & failure..

 

I don’t know what BMW has going on here but it is a known problem.. Not sure if it is the short spline engagement problem,, or soft shaft metal,, or clutch disk fit on the shaft to begin with, or even an alignment problem,, or a combination of more than one.. Whatever it is it’s a shame..

 

 

 

Twisty

[smiller]

And just to be clear on what you'll need to do or have done (beyond the clutch replacement) is replace input shaft of your transmission. This is about a $200 part (at one of the online parts dealers), plus of course a teardown of the transmission. You should also replace the seals while you're in there, maybe another $50. The work is doable by a moderately experienced home mechanic, the trickiest part will be re-shimming the new input shaft which will require a few special tools. If you need help there is plenty available here, or if you don't feel up to it a dealer can take care of at (at considerably higher expense of course.)

 

The biggest issue from my point of view is why it happened. As Twisty notes it isn't known for sure what causes this type of wear (it is not an uncommon problem on certain models and years) and there are a few theories.

[Steve W.]

Very bad looking splines and clutch. A common failure mode on these bikes. Much has been written about the mis-alignment of the engine-tranny. Do some searches on "clutch spline" here and on other lists. It's the luck of the draw if you get a good one or a bad one. I lube mine every 20k, and so far so good. You may "get by" with just a clutch and a lube, but I wouldn't stray far from home. Bad part is if you do the right repair (shaft, clutch, etc.) it's probably 50% of the bikes worth. But with the mis-alignment it will happen again. How much longer were you planning on keeping the bike? Tempting to throw some lube in there and ease it down to the local dealer for a quick trade in?

Good Luck

Steve 01 GS

[pfb]

Well, first off I will say thanks for the responses. After reading the posts I went

And took another look and now I see what’s going on. I don’t think my mechanical abilities include tearing down a transmission, at least not today. I need a fresh look at it tomorrow. I am going to call the dealer Monday and get some information and I will look into the alignment issue as well. I will add a clutch and slave cylinder to my parts list. I will keep you posted.

Thanks

Peter

 

a better look

[SoilSampler]

I hate to be mean but.......

 

Your input shaft splines are about 50% gone.

 

Your clutch disc is ready to fail at any moment.

 

Here is what my '02 looked like at 70,000 miles.

 

 

 

I would replace them both if it were my bike.

 

Stan

 

What was the lube interval, if any, on these splines?

[smiller]

What was the lube interval, if any, on these splines?

Technically there isn't one (according to BMW), and those who don't lube most often find dry, rusty splines in perfect condition when they do their first clutch job so there is certainly evidence that lubing for preventative maintenance isn't strictly necessary. It is often done to make clutch operation smoother though.

 

There have been many cases of spline failure however and at first lack of lubrication was blamed for this, but it would seem to me that additional analysis of this problem would lead to believe that there is actually some other factor at work in these cases, i.e. poor alignment during manufacturing, some unknown metallurgical issue, etc. But nothing is known for certain (by us anyway, BMW probably knows but they aren't telling.)

 

All that can be said for sure is that it certainly can't hurt to keep the splines lubricated (and it may even help bikes with an alignment or metallurgical problem live longer.) So the conventional wisdom is to lube every 40-60k miles. Again, from what I've seen I wouldn't sweat it, but then again I've never had a spline failure...

[Stan Walker]

What was the lube interval, if any, on these splines?

 

Never apart, never lubed prior to the pictures taken at 70,000 miles (actually 69,166).

 

I didn't see any of the rust others have talked about. Not a lot of original lubricant still present. Re-lubed with Moly-60. Clutch disc usable material was about 1/3 worn out and original disc is still in the bike today.

 

That same winter I also did Jan's '96 RT, also at about 70,000 miles (70,921). Splines were perfect (even better than the '02) but replaced the clutch disc anyway as I didn't think there was enough remaining clutch material to last until the next spline lube.

 

Stan

[Ken H.]

Couple more thoughts… Pay attention to what Stan is asking, “Clutch slave cylinder If you are sure it's brake fluid, replace it (no rebuild kit). If it was tranny fluid, replace the seal in the transmission.” From your description of what you found upon examination of the slave cylinder, it sounds like it might not be the leakage source. Rather the tranny’s rear input shaft seal. (The rear seal at the slave cylinder cavity.)

 

What is your long term thinking for the bike? A dealer rebuild of the tranny is going to be some $$. A used tranny with good splines and seals might be a more economical DIY choice. Or maybe you could cook up a deal here with someone experienced in this rebuild?

 

I will add that I did one that was about like yours and the owner was short on cash, so we just put it back together with a new clutch. It had lasted another 20K when he sold the bike. It’s a gamble though.

[T__]

I have the transmission off and below are the photos of the trans input splines and

the splines on the clutch side. Both are before cleaning. The area is pretty dry

So I’m glad I decided to do this. Trouble on the down shift was my impetus.

Now that it is all apart I figured I should at least check the clutch. The bike is a

2002 R1150R with 43k miles on it with no other previous symptoms. Never having

done this before I would like to make sure I’ve covered all the bases.

 

 

 

 

So here are my questions:

 

Clutch slave cylinder – upon removal about half a teaspoon of fluid ran out

Of the cavity in the trans. The end of the slave by the snap ring had a

Minimal amount crud buildup. Disassembly of the slave found the bore

Smooth and the gasket on the puck undamaged. Reassemble unit(after finding spring)

And set aside. Felt gasket thing on clutch rod slid out of trans easily and does not

Look swollen or damaged.

 

Question: is that amount of brake fluid enough reason to replace the slave cylinder ?

And if possible – is there a rebuild kit or do I have to buy the whole unit?

 

 

Trans input splines: They look like they are in good shape based on other photos I’ve seen but I can't be sure.

Questions:

1) How do the splines look?

2)Is the oil/grease buildup around the trans splines anything to worry about or

could that be The remnants of the original spline lube at the factory?.

 

 

Clutch - I’m looking at it and trying to figure out if I should check or change it or

Leave it alone.

 

Questions:

1) If I take it apart to measure the plate what thickness am I looking for.

2) If I remove the 6 bolts to check it can/should I use the old bolts or get 6

New ones recommended for a new clutch

3) Do the splines on the clutch look ok or should I replace the clutch solely based

On their condition?

 

One last thing- How much moly60 should be used

 

Thanks

Peter

 

Peter, could we possibly talk you into sliding your worn clutch disk back on the trans input shaft & line the depth & wear areas back up.. Then put a mark on the outer rim of the clutch disk & rotate it within it’s play just short of moving the input shaft..

 

That rotational play data would help a lot of fellow BMW R bike owners determine when their clutch splines are nearing the critical stage of wear.. That can be determined by pulling the starter & depressing the clutch then doing a rotational test in the bike..

 

Your wear point would be about where would most riders would need to start thinking about taking action..

 

Thanks________Twisty

[r77toy]

[

 

Peter, could we possibly talk you into sliding your worn clutch disk back on the trans input shaft & line the depth & wear areas back up.. Then put a mark on the outer rim of the clutch disk & rotate it within it’s play just short of moving the input shaft..

 

That rotational play data would help a lot of fellow BMW R bike owners determine when their clutch splines are nearing the critical stage of wear.. That can be determined by pulling the starter & depressing the clutch then doing a rotational test in the bike..

 

Your wear point would be about where would most riders would need to start thinking about taking action..

 

Thanks________Twisty

 

Then can you put it back together and ride it till it fails? Thanks for the pics.

[Mr. Frank]

It's amazing how some splines can fail at 30K miles and others can look like new at 70K miles. In the process of taking things apart to lube splines which look good is it possible to introduce the kind of alignment problem that creates excessive wear?

[Stan Walker]

In the process of taking things apart to lube splines which look good is it possible to introduce the kind of alignment problem that creates excessive wear?

 

I hope not!!!!!! But since the actual cause of the mis-alignment isn't known, it's hard to give a more positive answer.

 

Stan

[NonComp]

In the process of taking things apart to lube splines which look good is it possible to introduce the kind of alignment problem that creates excessive wear?

I'm interested in the possible relationship between rust and excessive wear. My shafts with 60K miles on them were still bright, but had little apparent lube on them. Others (like the OP's pics) are quite rusty. My bike has spent the past 12 years in a very damp climate. I would have thought it would be a candidate for rust. I wonder if varying composition of the metal used to create the shaft makes a difference. Are there known cases of early failure on the second round (after replacement) which would support an alignment issue?

[pfb]

could we possibly talk you into sliding your worn clutch disk back on the trans input shaft & line the depth & wear areas back up..

 

Sure, I can do that. I will post some pics in a couple of days. I'd like to see it myself. Dealers closed Monday's so I'm calling today. It's a big hit at the moment so I'm trying to decide what to do. I hadn't thought of a used trans or a local expert so I'll look in to those.

Thanks

Peter

[Anton Largiader]

The shaft is definitely at the replacement point. But with such low mileage I wouldn't reassemble it without taking some runout measurements on the clutch housing. I know this has been described in some other threads, either here or on Pelican.

[Ken H.]

It's amazing how some splines can fail at 30K miles and others can look like new at 70K miles. In the process of taking things apart to lube splines which look good is it possible to introduce the kind of alignment problem that creates excessive wear?

No, the dowel pins will insure that the transmission goes back to the same spot as before. If this issue is an alignment one, it's likely because the pins are misplaced to begin with during original manufacture. At least a couple of people have relocated them a few thousandths, having access to a shop capable of measuring and doing so. Whether or not that corrects their specific bike will of course take 10s of 1000s of miles/km and a disassembly again to ever know.

[Ken H.]

I'm interested in the possible relationship between rust and excessive wear. My shafts with 60K miles on them were still bright, but had little apparent lube on them. Others (like the OP's pics) are quite rusty. My bike has spent the past 12 years in a very damp climate. I would have thought it would be a candidate for rust. I wonder if varying composition of the metal used to create the shaft makes a difference. Are there known cases of early failure on the second round (after replacement) which would support an alignment issue?

Another theory about this issue, other than the alignment one, and I believe it was (is?) Ed's 'ShovelstrokeEd' favorite; is that this is indeed a metallurgy issue. He had a term for it, that I can't remember at the moment, but basically it was that with each power pulse the dry metal to metal was micro-welding, "sticking" the clutch plate spline and input shaft to each other then breaking the bond. 1000s of times a minute. And this was causing the eventual erosion of material we see. If true, it would support the idea that a lube (if in time of course) would prevent it, because it would prevent the stictition (sp?) of the materials to each other. Just a theory, maybe right, maybe wrong!

[ShovelStrokeEd]

Glen,

The brownish residue you are seeing really isn't rust. OK, it is iron oxide but it is not caused by moisture. It is something called fretting corrosion which is caused by the crankshaft impulses transferring through the splines. In essence, the acceleration and deceleration of the crankshaft, mostly at idle, btw, cause the forces on the clutch splines to alternate between faces. The clutch disk friction should mitigate against this but it doesn't all the time. The constant banging back and forth by a teeny little hammer effects this. Now, if you add a little mis-alignment and there are a number of types you have a formula for quickly wearing the splines.

 

I see this same wear and powdery residue in solenoids used for mass flow control of gases where the valve cycles at high frequencies. It can't be moisture in this case because the valve internals live in an environment of inert gases and are stainless to boot.

 

The fretting corrosion, by itself, won't cause that amount of war though, at least not in the short term.

[T__]

I still haven’t convinced myself the BMW R bike spline wear issue is an alignment problem.. Or even a lubrication problem.. I haven’t ever seen a similar lubrication problem on any other clutch system.. As far as alignment issues,, all the failures & spline wear I have seen on the BMW seems to point to the EXACT same alignment offset if it were an alignment issue.. That just isn’t possible to all be exactly the same over that long of a period of builds..

 

I have seen a lot of alignment induced wear issues on rotating parts from gear driven on spline shafts,, to spline coupling issues,, to large 2 cylinder clutch spline wear issues.. Nothing in these pictures tells me I am DEFINITELY looking at a specific alignment issue..

 

Now I’m not saying it CAN’T be an alignment issue or that alignment isn’t part of the equation but if it is an alignment ONLY issue I sure can’t see the smoking gun..

 

You would think if we were looking at a simple vertical or lateral alignment issue in relation to the crankshaft center line the spline wear would be full length spline wear not tapered in the short specific area that it is.. At first glance it looks like maybe an angular alignment problem in relation to crankshaft center line but you would think that would also show the taper wear on the front of the trans splines & a deeper wear path in the clutch disk.. That would also assume ALL the clutch spline failures had the same angular offset as to me all the wear pictures I have seen seem to look exactly the same only different degrees of wear..

 

If I weren’t looking at a motorcycle clutch but instead a drive shaft or splined coupling I would say at first glance it was a deflection of the spline mating area under load,, possibly coupled to some sort of power loading pulses..

 

I do tend to agree with ShovelStrokeEd that it is possibly some sort or sharp power pulse coupled with a fretting type stick/slip situation (maybe not the entire issue but sure a contributor).. But in my (limited ) estimation that would be what causes the metal loss but I can’t see that as causing the dished specific angular wear evident in the pictures.. I would also tend to agree with anyone that there is some sort of metallurgical problem there also.. A properly hardened shaft shouldn’t wear like that..

 

My own personal addition to this is with all that clutch mounting hardware from flywheel extensions, to floating front drive disk there sure is the possibility of clutch disk deflection not only under torque but at each sharp power pulse..

The auto companies have had some similar clutch issues or trans gear/ drive spline problems over the years with harsh firing 4 cylinders & diesels & a lot of those required dual mass flywheels to bring under control..

 

I have a bunch of old John Deere 2 cylinder tractors & those (especially the harsh firing diesels & large piston gassers) have had a clutch spline issue for ever.. It is a much different design clutch & the spline mate up is different but none the less they tend to beat the splines out & do it in a similar tapered wear pattern..

 

I am far from an expert in this field so don’t have the metallurgical back ground to say it IS this or that.. At this time I am under the belief that nobody has the entire failure picture here yet as to failure mode & ALL it’s causes & effects..

Having seen other similar failure issues in automobiles (not just a spline thing but odd wear & failure issues ) most are caused by a stack up of small problems compounded into a common failure.. That is why so many of those wear/breakage issues are so difficult to root cause.. If this BMW clutch spline issue was just a single misalignment,, or lubrication,, or part hardness issue it would have been rectified by now & so far I haven’t seen that..

 

Twisty

[Anton Largiader]

... the possibility of clutch disk deflection not only under torque but at each sharp power pulse..

 

Exactly my feeling. Misalignment (not necessarily the same every time) causes the hub to twist under load, or causes offset engagement, with the classic wear pattern. I had a few illustrations in the June OTL which might help some people visualize it.

 

Here's the thread where some of us were discussing measurements:

 

http://forums.pelicanparts.com/showthread.php?t=381041

[T__]

I guess a clutch problem is only a real important issue if it is difficult to get to & difficult to replace & makes you walk home..

 

My Ducati tears up the clutch plate drive ears about every 13,000-15,000 miles & about every other clutch takes an entire new engine driven clutch basket.. They all (the dry clutch models anyhow) seem to do this like clock work.. The price of a new clutch pack can run from a little over $100.00 to over well $300.00 with new basket..

 

Nobody really complains about it,, & some would like it to last longer,, & some applications do seem to last longer (depends on how hard you ride)..

 

The root cause are the harsh high compression 2 cylinder power pulses & soft aluminum clutch plate ears..

 

The saving grace that I can see that keeps the bitchin to a minimum is it is about a 15 minute install (slightly longer if a basket needed also) & they don’t leave you stranded.. The Ducati dry clutch gets so noisy as it wears that you WILL replace it long before it fails.. I have had real old people & even very young kids say is “your motorcycle going to blow up”? It sure sounds like it mister!!!!

 

Some of the newer Ducati models have wet oil dampened clutches now & there have been some complaints that people don’t like them as they don’t rattle like the old Ducati’s did..

 

I must admit that a clutch that rattles so loud that people think your bike is blowing up is a good conversation starter..

 

Twisty

[smiller]

But then a question... there have been several cases of multiple failures on the same bike and it would seem that such cases have to be somehow significant. Since the repair parts used in these multiple-repair cases presumably came from widely varrying batches this would seem to argue against an inherent metalurgical issue. Why would certain bikes be more prone to these issues while most others experience none?

[T__]

But then a question... there have been several cases of multiple failures on the same bike and it would seem that such cases have to be somehow significant. Since the repair parts used in these multiple-repair cases presumably came from widely varrying batches this would seem to argue against an inherent metalurgical issue. Why would certain bikes be more prone to these issues while most others experience none?

 

Seth, yes that is just another variable on this issue.. Is it the rider & his/her riding style or bike loading,, or engine operational smoothness?.. I sure don’t know the answer to that.. The lower power 1100 didn’t seem to have as much problem also didn’t have 6th gear to induce low speed high gear shudder..

 

Is it an alignment problems? Again don’t really know, possibly..

 

Is it a lube problem? (probably not if the NEW parts were lubed at installation)

 

Is it a high speed vs lots of stop & go issue? I can’t answer that..

 

Is it a crankshaft end play problem causing fore/aft firing deflections & movement? (again I can’t say)

 

Is it worn clutch material entering the spline area & causing accelerated wear? Who knows

 

Is it more than one of the above added together that causes the problem? (maybe, maybe not..

 

Is it something totally non related like storage time,, or powerwashing the bike,, or corrosion,, or trailering the bike in gear, or????

 

Is it something I missed here (probably)

 

Lab testing & long term durability testing needed.. Need to QUALIFY the parts & installation process before testing though..

 

This probably isn’t an easy one thing fix as it has not been identified & fixed yet..

 

Twisty

[smiller]

Well if the point is that it could be anything... I got that...

 

But the couple of instances where the same bike experienced multiple failures at relatively low mileages seems like a huge hint to me. It's unlikley that the circumstances surrounding metalurgy, lack of lubrication, etc. on these bikes would be an issue on multiple occasions at short intervals... if the original input shaft had a metalurgical issue, would the second or third installed on the same bike have the same problem? If there was no lubrication at the factory, would this same error have occurred multiple times? Could one rider be operating the bike under such unusual conditions so as to cause such a problem multiple times at short intervals? None of these seem very likely. Add this to the fact that the problem is rather rare overall (leading one away from an inherent design issue) seems to place the highest liklihood of cause on some kind of common defect on a limited number of units, and one that reoccurs after repair. I can't say for certain any more than anyone else but I sure know where that set of circumstances tends to lead me.

[nrp]

Every failure that has had the radial alignment measured, has shown misalignment. Admittedly few have done that, but repeat failures using the same housings etc seem to be common.

 

I don't buy into the torsional impulse concepts either, as then the problem would be much more common, and repeatable.

 

Fretting corrosion (OK, rust) happens from two pieces of steel rubbing against each other under high load and a very high number of cycles. If the alignment were near perfect, there would be no rubbing, and all of the spline teeth will carry and share the load (torque). However, it requires very good alignment to reach this condition - especially given the short shaft from the transmission and the radial stiffness of the clutch hub.

 

My guess is that the engine to transmission radial alignment has to be within .001 or .002 inch total indicated runout (TIR) for this not to be a spline assembly life problem. That's not an easy cumulative accuracy in a production environment.

 

The reason cars don't experience this failure mode is the transmission input shafts are longer and much more flexible, and many times there is also a clutch pilot bearing to control alignment. Maybe they have just figured out the alignment accuracy needed for reliability.

[nrp]

Some have suggested the barrel shaped wear pattern suggests angular misalignment. If you look critically at the pictures, the shaft splines are most worn adjacent to the transmission, and the clutch housing splines are most worn next to the engine block.

 

Mating surfaces such as these that are subject to fretting, will always wear to what's called a conjugal condition which only maintains physical contact along the entire wearing surface. This spline wear suggest that a slight differential hardness has caused this differential wear pattern. The surfaces are still conjugal. If the mating surfaces were both barrel (and inverse barrel) shaped, then I would agree that there is an angular alignment problem. In this case a mating spline can only have point contact along the faces of the teeth. I don't think that's the case here.

 

Another remote possibility though could be worn main bearings in the engine, that would allow the crankshaft to rattle back and forth from power impulses. Some of the piston forces could be transmitted all the way across the spline to the transmission input shaft bearing.

[T__]

NRP,

 

Every failure that has had the radial alignment measured, has shown misalignment. Admittedly few have done that, but repeat failures using the same housings etc seem to be common.

 

I would imagine that EVERY BMW R bike measured even the non failed ones would show misalignment.. Probably some fairly significant.. How much too much? I would think in similar situations .005”-.007”would the limit.. No way to build anything like that to be that perfect, just no way.. If it was a radial alignment problem why the wear ONLY in the rear & not across the entire spline.. If it was misaligned in the rear it would also be in the front.. If it was an alignment problem I would more believe it to be an angular alignment problem than a radial alignment problem.. At least that could sort of explain the tapered wear pattern..

 

I don't buy into the torsional impulse concepts either, as then the problem would be much more common, and repeatable..

 

It does seem to be somewhat common.. What we don’t know here is the extent of wear on the non failed bikes out there now.. We don’t hear or see them until failed & then not dealer repaired bikes or people that don’t use the internet.. It does seem to be more prevalent in the 1150 bikes.. Is that a build problem or the added torque of the larger engines?

 

 

Fretting corrosion (OK, rust) happens from two pieces of steel rubbing against each other under high load and a very high number of cycles. If the alignment were near perfect, there would be no rubbing, and all of the spline teeth will carry and share the load (torque). However, it requires very good alignment to reach this condition - especially given the short shaft from the transmission and the radial stiffness of the clutch hub.

 

I guess you have never seen high speed of shafts, clutches & couplings operating under load & in the inherent vibration operational area of engine or trans.. They shake,, twist,, rotate,, slide,, distort.. If you ever saw a high speed of the event you wouldn’t say what you did here.. That clutch hangs off the back of the flywheel so has the ability to flex & move around under both load & vibration..

 

My guess is that the engine to transmission radial alignment has to be within .001 or .002 inch total indicated runout (TIR) for this not to be a spline assembly life problem. That's not an easy cumulative accuracy in a production environment.

 

That would be W-A-Y closer than the industry average of similar matchups.. It would be so costly to try & maintain that close of a TIR.. If that was needed there would have been a re-design before production to remove that dependence.. Based on similar automotive applications I would guess closer to .005” to maybe as high as .007” TIR.. To keep it at .001”-.002” TIR would require hand measurement & fitting of each trans to clutch & engine.. If it takes .001” to .002” to keep from failing there would be no room for even the slightest rear engine bearing wear as that would drive it out of specs.. You might convince others of this tight a spec but sure won’t convince me as I work in this area for a living..

 

 

The reason cars don't experience this failure mode is the transmission input shafts are longer and much more flexible, and many times there is also a clutch pilot bearing to control alignment. Maybe they have just figured out the alignment accuracy needed for reliability.

 

We have some shortys in some of the new Getrags as well as much higher torque loads to handle.. The short stub shaft of the BMW application probably does have some bearing on the problem but how much we don’t know.. If anything I would like to see the stub shaft at least extend through the clutch hub..

 

Twisty

[Anton Largiader]

Every failure that has had the radial alignment measured, has shown misalignment.

Not in my experience. Once you compensate for the bearing clearance, it's pretty much centered on the ones I've measured. I wonder how many people saw that the crank was slightly lower than the tranny bore and called it mismachining. IIRC I can measure about .12mm vertical movement of the crank, which is about the same as the .005" some people measure, which just about matches the combined error if you disregard the oil film.

[T__]

Anton, have you ever measured the angular line up vs the crankshaft C/L?.. IE. Mounted a dial indicator to the flywheel & swept the rear face of the engine case at trans mounting area,, then mounted a dial indicator on the trans input shaft & swept the trans case front face where it mates to the engine case?

 

I would be interested in what you have recorded there..

 

Twisty

[NonComp]

Very interesting. It would be fun (but likely impossible) to correlate poor tuning/carb balancing and/or percentage stop-and-go communting vs. highway driving and/or individual driving style (hard on/off throttle, lugging, idling, etc. etc.) with premature failure.

 

One thing seems clear, though. The red oxide appears to be indicative of abnormal wear -- not corrosion. So if you pull the starter and take a look up there with a flashlight and "see red" you probably want to do more than a quick lube.

 

I wonder if a heavier flywheel would make a difference?

[Anton Largiader]

Anton, have you ever measured the angular line up vs the crankshaft C/L?

Nope. I check axial alignment (never find anything meaningful) and runout. It's the runout where I think a lot of problems lie.

 

As I said in the June OTL, if you don't want to measure a bunch of stuff, replace everything between the crankshaft and the tranny. Once you have a spline failure it's all suspect IMO.

[daveinatlanta]

A basic and perhaps dumb question: What does shifting difficulty have to do with splines? I've read somewhere in these fora that one possible sign of spline problems is some difficulty in shifting. I don't understand that premise because it seems to my pretty simplistic mind that when the clutch is disengaged, everything behind it is either not moving or moving in accordance with the speed of the bike. If there is a problem in shifting, the clutch does not disengage properly or there is some problem in the xmsn. In either case, bad splines would not seem (to me) to be a problem. But what do I know.... That's why I'm posting this.

 

FWIW, I did Jamie's mini-spline lube several weeks ago - ref Splinal tap. That's the minimally invasive procedure wherein I removed the starter, took a bright light, used a long probe that a Proctologist would be proud of to get a little lube on the visible part of the splines. The assumption is that the lube will eventually find its' way back to the part of the splines that really matter. I'll never know whether this helped and I probably won't have this bike long enough to get to the point where I need a new clutch or experience some other malfunction that will necessitate a complete removal of the transmission and a proper lube of the splines. The bike is an 04 RT with 40K on it. The part of the splines I could see looked fine. But, again, that part probably does not matter.

[T__]

A basic and perhaps dumb question: What does shifting difficulty have to do with splines? I've read somewhere in these fora that one possible sign of spline problems is some difficulty in shifting. I don't understand that premise because it seems to my pretty simplistic mind that when the clutch is disengaged, everything behind it is either not moving or moving in accordance with the speed of the bike. If there is a problem in shifting, the clutch does not disengage properly or there is some problem in the xmsn. In either case, bad splines would not seem (to me) to be a problem. But what do I know.... That's why I'm posting this.

 

FWIW, I did Jamie's mini-spline lube several weeks ago - ref Splinal tap. That's the minimally invasive procedure wherein I removed the starter, took a bright light, used a long probe that a Proctologist would be proud of to get a little lube on the visible part of the splines. The assumption is that the lube will eventually find its' way back to the part of the splines that really matter. I'll never know whether this helped and I probably won't have this bike long enough to get to the point where I need a new clutch or experience some other malfunction that will necessitate a complete removal of the transmission and a proper lube of the splines. The bike is an 04 RT with 40K on it. The part of the splines I could see looked fine. But, again, that part probably does not matter.

Dave, what causes the shifting problems (usually down) is the clutch disk hub splines binding due to that cupping & uneven wear (the splines of the disk jams on the splines of the trans input shaft). That usually happens under some clutch loading so the clutch disk was in hard contact with both the drive & driven plates on the flywheel.. When the clutch lever is pulled in it releases the movable plate on the flywheel but seeing as the disk splines are jammed up & won’t slide the clutch disk still stays tight to the fixed flywheel clutch drive plate..

 

Or to state it simply__ the clutch doesn’t fully release on the downshift..

 

As for that moly grease migrating.. The very trait that makes moly grease stay put for miles & miles of usage usually means it won’t migrate on it’s own…It will travel slightly as the clutch disk slides in & out on the input shaft splines a little but that’s about it..

 

Twisty

 

 

 

[nrp]

Anton - How much clearance are you measuring in the main bearings? .005 inch sounds like about three times too much to me.

 

Are you measuring with a dial indicator from the flywheel registering to the transmission input bearing bore? and with an appropriately rigid indicator setup?

[daveinatlanta]

Dave, what causes the shifting problems (usually down) is the clutch disk hub splines binding due to that cupping & uneven wear (the splines of the disk jams on the splines of the trans input shaft). That usually happens under some clutch loading so the clutch disk was in hard contact with both the drive & driven plates on the flywheel.. When the clutch lever is pulled in it releases the movable plate on the flywheel but seeing as the disk splines are jammed up & won’t slide the clutch disk still stays tight to the fixed flywheel clutch drive plate..

 

Or to state it simply__ the clutch doesn’t fully release on the downshift..

 

Well - the last sentence is the bottom line and I'll accept it. But, at some point, I guess I need to get a better understanding of how the splines move laterally. I didn't think they did. I thought that once the rear part of the clutch and transmission were assembled, there was no lateral (or in and out) movement. Guess I need to pull out the diagram of the relevant parts again.

 

Thx.

[T__]

Dave, what causes the shifting problems (usually down) is the clutch disk hub splines binding due to that cupping & uneven wear (the splines of the disk jams on the splines of the trans input shaft). That usually happens under some clutch loading so the clutch disk was in hard contact with both the drive & driven plates on the flywheel.. When the clutch lever is pulled in it releases the movable plate on the flywheel but seeing as the disk splines are jammed up & won’t slide the clutch disk still stays tight to the fixed flywheel clutch drive plate..

 

Or to state it simply__ the clutch doesn’t fully release on the downshift..

 

Well - the last sentence is the bottom line and I'll accept it. But, at some point, I guess I need to get a better understanding of how the splines move laterally. I didn't think they did. I thought that once the rear part of the clutch and transmission were assembled, there was no lateral (or in and out) movement. Guess I need to pull out the diagram of the relevant parts again.

 

Thx.

 

 

Dave, the clutch disk MUST slide slightly on the splines to pull away from the flywheel drive plates upon clutch release. If it didn’t it would always drag on the drive plates when released… If it didn’t need to move (slide slightly) there would be no need for splines to begin with..

 

Kind of like the disk brakes in you car.. If the brake pads didn’t pull back slightly upon release the brakes would always drag on the rotor..

 

Twisty

[Anton Largiader]

Anton - How much clearance are you measuring in the main bearings? .005 inch sounds like about three times too much to me.

 

I'm going from memory here; last one I did was last summer, but I'm pretty solid on the 0.12mm. That happens to be the wear limit of the radial clearance. I measured that with a dial indicator on an alignment arbor, prying the base of the arbor (and therefore the crank) upward with the tranny cover installed.

 

I have records on the ones I've measured but digging them out isn't on the agenda this week...

[barryNmarin]

 

 

Here are a couple of photos of my 04RT clutch spline and clutch plate which failed at 50050 miles while crossing B.C. Canada this summer. Cost me about $2100.00 to get back on the road plus a round trip plane ticket from Calgary to SF and back. Normal wear and tare? Misallaignment of some kind?? I just hope I don't have to do this again at 100K.

 

Barry

 

 

[nrp]

Barry - You can check the spline condition by removing the starter and bungee the clutch handle in. Then measure the backlash in the spline by carefully wiggling the clutch disk outside diameter in a tangential direction. Note that backlash. It should be about 1/8 inch now that they are new. Check it again in 20K miles to get a feel for how much your spline has worn. I'd guess a max would be about 1/4 inch before you are looking at another failure.

 

Others may have better numbers.

 

Those PIX are sickening.

[Ken H.]

Dave,

 

Remember, there are two sets of splines, those on the input shaft of the transmission, and those on the clutch friction plate that circles the input shaft. When you pull the clutch the push rod pushes on the diaphragm spring releasing pressure on front pressure plate and at the same time the clutch friction plate must slide forward a bit to disengage it from the spinning rear pressure plate. If this back to front movement of the clutch friction plate sliding forward on the transmission input shaft is impeded, by dry or worn splines on either part, the clutch continues to try to apply some torque to the transmissions input shaft, and that prevents a smooth shift within the tyranny from happening.

[awagnon]

As I said in the June OTL, if you don't want to measure a bunch of stuff, replace everything between the crankshaft and the tranny. Once you have a spline failure it's all suspect IMO.

 

Anton. Are you saying that replacing the clutch disk and the tranny input shaft isn't enough? You would replace the entire clutch assembly, including the pressure plate and housing?

 

Barry. When your bike ate it's splines in Canada, what all did you have replaced and how many miles has it been since?

[Stan Walker]

I've been "sorta" following the Hexhead babble and I don't recall hearing about any spline failures, lots of bad final drives, but nothing else in the drive train as best as I can remember.

 

Maybe, just maybe, BMW has finally defeated the splines. If so, it would be interesting to find out just what changes they made to do so.

 

Stan

[barryNmarin]

Neil, thanks for the tip. If I'm lucky I'll be on a new ride before I have to seriously consider the status of the spline.

I will definitely give it a look if I have an occassion to remove the starter.

[barryNmarin]

I just replaced the shaft seal bearing. I would have replaced the other seals/bearings while they had the tranny case cracked open but the shop didn't have the BMW tool required to do that job. It was an independent german bike shop and not a BMW franchise. They had never seen a clutch spline failure like this. I've put on 7000 miles since the July repair job. It is running/shifting like new although there has always been a clunk shifting into 6th gear.

[Anton Largiader]

As I said in the June OTL, if you don't want to measure a bunch of stuff, replace everything between the crankshaft and the tranny. Once you have a spline failure it's all suspect IMO.

 

Anton. Are you saying that replacing the clutch disk and the tranny input shaft isn't enough? You would replace the entire clutch assembly, including the pressure plate and housing.

 

I'm saying that if you don't want to take measurements to try to identify a certain problem, you replace everything in back of the crank.

[AndyS]

As for that moly grease migrating.. The very trait that makes moly grease stay put for miles & miles of usage usually means it won’t migrate on it’s own…It will travel slightly as the clutch disk slides in & out on the input shaft splines a little but that’s about it..

Twisty

How about if you dilute the Moly with IPA (alcohol) and syringe it in, would not the IPA act as a carrier until it evaporated, then leave the suspended moly in place?

Andy