Spline Failure

[matanuska]

I just finished my first engine / transmission alignment check. As I mentioned before, I measured the bore of the transmission input shaft at 10.00mm and the bore of the engine output shaft at 6.00mm. I used a 12” piece of 10.00mm precision ground drill rod stock and turned a 1” long section on one end to 6.00mm to make a Go / No-Go gauge. A remounted the transmission to the engine bell housing without the clutch installed and checked alignment with my gauge.

 

Based on this, I can say, without a doubt that the engine output shaft and transmission input shaft are definitely NOT aligned. The gauge will not slip into the 6mm bore of the engine output shaft.

 

Because of the unique design of the K12RS transmission, I haven’t figured out how to actually measure the misalignment. Once that is done, I’ll have to come up with some way to correct it. Based on all of the spline failure posts I’ve read in the Oilhead section, I’m particularly interested to see the inside of the transmission cover when I open it up to replace the transmission input shaft. Sounds like there have been problems there with bearing holes bored offset to the cover casting causing radial displacement of all the transmission shafts relative to the housing. If this is the cause in mine, it might be a relatively simple fix.

 

More to follow…

 

Derek

[Dennis Andress]

Wow. Now I'm interested, keep going.

 

Dennis

[bmwmick]

Derek,

Started a whole new thread???????????

 

Back on the other thread, did you even show the engineering buddy at work the Input shaft? The way it is worn almost ensures you have some type of angular alignment issue. The

two shafts (output and input) are NOT in the same Plane!

Again.....

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.I've seen several that look just as good as mine at high mileage too.

 

 

Mick

[No_Twilight]

Derek,

Started a whole new thread???????????

 

Back on the other thread, did you even show the engineering buddy at work the Input shaft? The way it is worn almost ensures you have some type of angular alignment issue. The

two shafts (output and input) are NOT in the same Plane!

Again.....

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.I've seen several that look just as good as mine at high mileage too.

 

 

Mick

 

Mick,

Are you talking about the engineering buddy that sold him the defective bike??? that was me.

 

We looked at the clutch and had our high dollar failure expert look at it under a microscope and we saw no real evidence of an angular misalignment. However, a parallel but not coaxial shaft misalignment makes sense. Now Derek said he didn't find any lubricant in the vicinity (most of the lubricated metal was sheared off however..) so I'm not ruling out the lubrication issue myself.

 

I'll be eager to talk to Derek at work on monday. From his description above it seems difficult to measure how misaligned he really is...

 

BTW, Derek is an accomplished machinist and very capable of diagnosing these things without his engineering friend--however, two heads are always better than one.

 

And BTW I agree with you that if they don't have a problem then they'll probably last forever. My R-bike has 90k on it. My backup R-bike that Derek is riding has 80 something K on it and a buddy at work has 230something k miles on his. My new Yamaha R1 had 6k on it and I don't think it even has an input shaft....

 

--Jerry

[nrp]

>I just finished my first engine / transmission alignment check. As I mentioned before, I measured the bore of the transmission input shaft at 10.00mm and the bore of the engine output shaft at 6.00mm. I used a 12” piece of 10.00mm precision ground drill rod stock and turned a 1” long section on one end to 6.00mm to make a Go / No-Go gauge. <

 

It isn't apparent to me yet just what you have done. You mentioned the bore in the crank (?) and in the input shaft (?) - are these necessarily the running surfaces? If your prototype mandrel is so long yet so small in diameter, how do you get it straight?

 

I wish I understood the nature of the assembly so I could help you with a inherently accurate runout measurement system.

[James Clark]

I just finished my first engine / transmission alignment check. As I mentioned before, I measured the bore of the transmission input shaft at 10.00mm and the bore of the engine output shaft at 6.00mm. I used a 12” piece of 10.00mm precision ground drill rod stock and turned a 1” long section on one end to 6.00mm to make a Go / No-Go gauge. A remounted the transmission to the engine bell housing without the clutch installed and checked alignment with my gauge.

 

Based on this, I can say, without a doubt that the engine output shaft and transmission input shaft are definitely NOT aligned. The gauge will not slip into the 6mm bore of the engine output shaft.

 

Because of the unique design of the K12RS transmission, I haven’t figured out how to actually measure the misalignment. Once that is done, I’ll have to come up with some way to correct it. Based on all of the spline failure posts I’ve read in the Oilhead section, I’m particularly interested to see the inside of the transmission cover when I open it up to replace the transmission input shaft. Sounds like there have been problems there with bearing holes bored offset to the cover casting causing radial displacement of all the transmission shafts relative to the housing. If this is the cause in mine, it might be a relatively simple fix.

 

More to follow…

 

Derek

 

 

Let my try again.

 

Take an aluminum tooling plate blank. Relieve one face to clear the gearbox cover. Square the faces to insure flatness. Drill all of the mounting holes that hold the gearbox to the clutch housing. Drill and ream for any alignment dowels. Drill and bore a center hole where the input shaft and "crank" shaft should be.

 

Bolt the plate to the clutch housing using the alignment dowels. Secure an indicator to the "crank" and rotate the shaft. Note the direction and quantity of any eccentricity between the shaft and the bored hole.

 

Move the plate to the gearbox flange, using the dowels. Secure the indicator to the input shaft and note any eccentricity between that shaft and the bored hole.

 

Ideally, they will both show the sane eccentricty to the bore. Otherwise, you will have to to a polar-cartesian conversion to calculate the eccentricy between the shafts.

[matanuska]

...You mentioned the bore in the crank (?) and in the input shaft (?) - are these necessarily the running surfaces? If your prototype mandrel is so long yet so small in diameter, how do you get it straight?

Because I made it that way. The stock I used (from McMaster) has a stated runout of less than 0.005” per foot and diametrical tolerance of +/- 0.013mm (and I verified this on a lathe). I turned the small end with zero runout (less than 0.0001”) and diametrical tolerance of +/- 0.0002”. If the shaft bore of the input shaft is nominally 10.00mm (actually, probably 10.01mm or 10.02mm) over a length of about 4.25”, and a gauge of 10.00mm will slide thru the entire length without binding, chances are it’s pretty straight. Finally, measured runout of the gage while rotating the input shaft was less than 0.002”, so it’s pretty safe to say the bore is concentric with the shaft.

 

Anyway, as I mentioned before, this test wasn’t designed to provide any empirical data in the first place. Just to let me know if the two shafts are in alignment or not. They obviously aren’t, so I’ll need to move on to find a way to diagnose and correct the condition.

 

I wish I understood the nature of the assembly so I could help you with a inherently accurate runout measurement system.

 

If you look at the picture on my last thread, you see the transmission cover is on the front, inside end of the transmission casing. On an R tranny, you can bolt the casing up to the engine bell housing and still remove the transmission cover from the rear giving access to take measurements of the engine output shaft relative to the transmission. On my K, once the transmission case is bolted to the engine, there is no access to the inside at all. The best I could do is to remove all of the shafts and bolt up the casing and be able to peer through the two empty holes left by the input and output shafts at the back.

 

Obviously, the best way to measure everything would be to throw the entire motorcycle, tranny, and shaft assemblies up onto a big Coordinate Measuring Machine (CMM) with a 10’X10’ table and build a CAD model of the whole shebang. Since I don’t have access to one of those, I’ll need to do it in a more roundabout way. I figure I’ll take measurements of all the assemblies referencing them to the plane described by the transmission / bell housing joint and X / Y coordinates referenced to the locating pins on the engine.

 

I’ll post more pictures as I progress. Any ideas or suggestions would certainly be welcome.

 

Cheers

DR

[matanuska]

...Back on the other thread, did you even show the engineering buddy at work the Input shaft?...

As I also mentioned on the last thread, my “real” job is to perform Cause Analyses when people (including Engineers) make mistakes! Unfortunately, there is plenty of work! No Maytag repairman here!

[matanuska]

...Take an aluminum tooling plate blank. Relieve one face to clear the gearbox cover. Square the faces to insure flatness. Drill all of the mounting holes that hold the gearbox to the clutch housing. Drill and ream for any alignment dowels. Drill and bore a center hole where the input shaft and "crank" shaft should be.

 

Bolt the plate to the clutch housing using the alignment dowels. Secure an indicator to the "crank" and rotate the shaft. Note the direction and quantity of any eccentricity between the shaft and the bored hole.

 

Move the plate to the gearbox flange, using the dowels. Secure the indicator to the input shaft and note any eccentricity between that shaft and the bored hole.

 

Ideally, they will both show the sane eccentricty to the bore. Otherwise, you will have to to a polar-cartesian conversion to calculate the eccentricy between the shafts.

 

An excellent idea!

This is probably the direction I was stumbling towards, only would have taken me allot longer to get there on my own!

 

BTW, where in SoCal are you located?

 

Derek

[nrp]

I think I understand your problem now. A tooling plate with a reference bore may be the only way to go. How thick does it have to be? Is it completely impossible to read a small crank mounted indicator thru the transmission holes? even with a mirror?

 

What is the 6 mm diameter hole in the crank for? Is it a controlled diameter that is concentric to the crank journals?

 

I would expect the runout to be less than say .003 inch for a reliable spline situation.

 

You (we) have a nasty problem. Keep us posted.

[bmwmick]

...Back on the other thread, did you even show the engineering buddy at work the Input shaft?...

As I also mentioned on the last thread, my “real” job is to perform Cause Analyses when people (including Engineers) make mistakes! Unfortunately, there is plenty of work! No Maytag repairman here!

 

Derek,

What I'm getting at is the 'barrel-shaped' wear on the input shaft splines. The splines look pretty good at at the end towards the engine but there is a pronounced 'ring' back at the rear, nearest the tranny. This was cause by the whole clutch hub, and/or clutch housing, wobbling on that shaft as it rotated(or the tranny is coming at the engine at an angle). The friction disc surface is held clamped between the pressure plates and the flex plate between the friction material and the hub is actually flexing as it rotates. This is exactly what the old K-Bikes looked like when they had a bad batch of intermediate housings.

 

Mick

[nrp]

A possible answer to the longitudinally skewed spline wear may be the relative deflection of the clutch disk center and the transmission input shaft when the clutch disk is generating a radial load. If the disk is being dragged around the flywheel face by radial misalignment, the radial load could easily be a couple of thousand pounds.

 

Without seeing the clutch disk, I'll bet the female spline is not longitudinally centered on the clutch disc web/spider. That could concentrate the radial fretting load vector and resulting wear near the rear end of the transmission input shaft spline.

[bmwmick]

A possible answer to the longitudinally skewed spline wear may be the relative deflection of the clutch disk center and the transmission input shaft when the clutch disk is generating a radial load. If the disk is being dragged around the flywheel face by radial misalignment, the radial load could easily be a couple of thousand pounds.

 

Without seeing the clutch disk, I'll bet the female spline is not longitudinally centered on the clutch disc web/spider. That could concentrate the radial fretting load vector and resulting wear near the rear end of the transmission input shaft spline.

 

I think we saw one of those on an Oilhead just not too long ago. The friction disc was running around like an orbital sander. The wear was even on that one. IIRC

 

Mick

[Carnadero]

..I'll bet the female spline is not longitudinally centered on the clutch disc web/spider. That could concentrate the radial fretting load vector and resulting wear near..

[James Clark]

BTW, where in SoCal are you located?

 

"West" OC

[matanuska]

OK, here’s an interesting development. Last night I was messing around, going over various ideas for making up a test fixture for the engine and tranny. I loosely bolted the tranny back up to the engine flange and discovered I could force my go/no-go gauge in if I manipulated the trans a little. After some more testing, I found that by raising the back of the tranny with a jack to the extreme limit allowed by the slop in the two locating pins, the gage effectively slips in with no resistance! The two shafts are in alignment! Maybe not dead-nuts on, but certainly a quantum improvement over the original condition!

 

This configuration results in a gap of about 0.025” at the bottom of the bell housing / transmission joint. At the back end of the transmission at the frame attachment point, this translates to a 1/8” vertical movement to achieve this gap. If anyone cares to do the math I’m sure you could calculate the amount of angular misalignment (definitely not that much!). I’m just happy to be done with it!

 

So, here’s the question – given that I can align the shafts now (even though the true cause of the problem isn’t actually known), I can think of several possible courses of action:

 

1. Put everything back together and install a 0.025” thick strip of shim stock along the bottom engine / transmission joint to give the correct gap. Obviously the easiest solution, but results in a less than optimal engine/trans joint (i.e. loss of full contact around the entire flange).

2. Put the whole transmission up on my Bridgeport mill and take a slight skim cut on the front mounting flange to achieve the required angle when bolted to the engine. Second simplest solution – the tranny is already off – but if I screw it up, my tranny is FUBAR.

3. Remove the engine bell housing and mount it on the mill to do the same thing. Requires more work to remove the bell housing but a new one is cheaper than a new tranny if I mess something up.

4. Continue with my inspections and if I determine it’s the bell housing that’s not square, buy a new one. The cleanest solution if the bell housing is at fault, but requires the most work. Do I really need to continue all this troubleshooting if I know how to solve the problem?

 

What do you guys think? Right now I’m leaning towards #2, but I’m seriously considering #3 as well. Any suggestions?

 

Derek

 

Engine with Tranny jacked to the corrected position:

 

 

Resulting gap at bottom of joint:

 

Close-up of gap:

 

Top of tranny – hard to tell but the joint still is metal-to-metal:

 

Larger images:

 

Image 1

Image 2

Image 3

Image 4

Image 5

[bmwmick]

Derek,

I'm leaning towards #3 or #4. If you DO order a new intermediate housing, make sure you have the option of

rejecting it if you measure it and find it as bad as your original (assuming you find a dimension you can count on).

P/N 11 14 1 465 092 is only(?) $278 from Chicago BMW.

 

Mick

[matanuska]

Thanks Mick,

 

The more I think about it too, it makes sense to go the extra to remove the flange and see what’s up (I’ve already come this far). Maybe there was some simple (easily correctable) error made in the way the flange was bolted up to the engine. I notice from the service manual that there is some kind of sealant applied to the top of the intermediate flange upon installation. On the bike currently, it looks like this sealant is kind of thick up at the top. Is this just a coincidence that my check shows the flange is misaligned slightly out too far at the top?

 

Have you ever removed this component from a K before? Any suggestion?

 

DR

[bmwmick]

Derek,

I've never had to replace one of MINE but I've helped on others. The Alternator drive bearing and seal is the the only thing I remember giving us any problems. Didn't have the correct puller for the bearing. New needle bearings for the counter shaft would probably be a good idea too.

I have no idea what Omni VISC 1002 is (the sealant they call for in the manual) but I would guess a thin coat of Permatex Ultra Black Silicone would work just fine. That is what we used. It will be interesting if you find 0.025" thickness of sealant at the mating surface. That would definitely give you the angular misalignment you are seeing at the shaft.

You'll need to support the engine separately from the frame to remove the housing. (Nevermind, the K1100 uses the intermediate housing as the upper rear mount, yours uses the tranny)

I forget, how many miles on this bike? On the old K-Bikes, the housing problem would destroy a clutch about every 25K miles.

 

Mick

[matanuska]

Just finished removing the Intermediate Flange. I got it cleaned up and put it on my surface plate. It is slightly out of square, but only by 0.004", probably within the OEM spec. The mounting surface to the engine block looked nice and clean too. No evidence of any problems during fit up. Hardly the smoking gun I was looking for. Guess I'll have to keep plodding along...

 

DR

[bmwmick]

Derek,

If you can take some good measurements and skim 0.025" off the rear upper surface of the intermediate housing, that sounds like the best fix at this point. You could have 0.004" of misalignment at the intermediate housing and 0.021" or so at the front cover of the tranny adding up to cause your shaft misalignment.

Are you confident that the 0.025" gap actually corrected the misalignment into the output shaft of the engine? If so, I think you have a good plan to prevent a recurrence by cutting the intermediate housing. Then you'll have a 'custom' matched assembly. There IS a little bearing play in the tranny input shaft but very little on the engine output shaft bearing.

 

Mick

[matanuska]

...Are you confident that the 0.025" gap actually corrected the misalignment into the output shaft of the engine?

Not enough yet to justify taking the cut!

 

Last night, I took some further measurements. Now that I have the Intermediate Flange off, it actually became a simple matter to mount a dial indicator and measure various angular alignments. So far I’ve checked:

 

Squareness of the Clutch surfaces to the engine output shaft axis.

Squareness of the engine output shaft axis to the Intermediate Flange mounting surface.

Parallelism of the front and back Intermediate Flange mounting surfaces.

Squareness of the Transmission input shaft axis to the Intermediate Flange mounting surfaces.

 

So far, everything is within +/- 0.002” (including the Intermediate flange mounting surfaces after I bolted it up to the transmission housing). Only thing left to check is the radial alignment of the Engine Output and Transmission Input shafts.

 

If the two shafts are in fact slightly offset to each other, it could be when I tilted the tranny slightly the other day this simply pointed the end of the shaft more towards the end of the engine shaft allowing the gauge to slide in, but created slight axial misalignment at the same time. In other words, if I take the cut I might just be trading radial misalignment for angular misalignment (though I suspect the latter would be less destructive in the long run).

 

I will know more when I make up a test fixture to perform the final measurement in the next few days. I just hope I’m able to find SOMETHING. It will really suck if the measurement shows the shafts are aligned. What would that mean?

 

DR

[bmwmick]

I will know more when I make up a test fixture to perform the final measurement in the next few days. I just hope I’m able to find SOMETHING. It will really suck if the measurement shows the shafts are aligned. What would that mean?

 

DR

 

I guess that would mean we've ALL been the 'Twilight Zone' for this entire process. 0.002" in any axis is NOT going to result in the wear you saw unless the clutch hub was slightly tilted in relation to the friction surfaces.

Hard to measure that now.

 

Mick

[ELP_JC]

I'm sure probably all here know this, but wanted to mention this due to a 'crank' comment. The engine output shaft is not the crank; it's a shaft below it, driven by a beveled gear. Good day.

[James Clark]

I'm sure probably all here know this, but wanted to mention this due to a 'crank' comment. The engine output shaft is not the crank; it's a shaft below it, driven by a beveled gear. Good day.

 

If you're going to be pedantic . . .

 

It's driven by a helical gear.

[matanuska]

Just finished making my test plate to measure shaft alignment. I measured a 0.011” offset between the engine output and transmission input shafts. Is this the smoking gun I’ve been looking for? Would this be enough misalignment to produce spline failure in 33k miles?

 

 

I was hoping to see something really glaring like 0.030”, but this is a little more subtle. It would be nice to know what the factory spec for the alignment is. If 11 thou really is capable of producing this much damage, I would think most splines out there must be pretty close to dead-nuts on.

 

Correcting this misalignment shouldn’t be all that difficult. The transmission housing would need to be shifted up by the corresponding amount. I would probably plug the two locating holes in the transmission casing then bore and ream them to size in the correct location. Since the offset is so small, I could probably just bore out the four remaining transmission bolt holes to accommodate the move.

 

Question is though; is all this really worth it for a measly eleven thousandths of an inch?

[nrp]

Derek -

 

I don't know what else there is in the drive connection between the engine output and the transmission input shaft that will accommodate .011 inch of shaft rotation axis difference. Surely the transmission input shaft is radially very rigid, and I suspect the engine output shaft is too.

 

Actually I would have expected wear problems to start to show at perhaps .003 inch TIR, at which point I would guesstimate the individual spline teeth loads due to transmitted torque, might be cycling say +/- 50% every revolution (that's an eyeball finite element analysis based on 43 years of mechanical engineering experience!) Note that this is a two component wear pattern that will never "wear in". It is simply high frequency fretting that's unending.

 

Again I'm not familiar with the assembly details. There was talk earlier of there being a gear-driven jackshaft output rather than the crankshaft itself. Is the bearing system of this jackshaft loose by chance? Tangential gear tooth loads will make such an arrangement shift the rotating axis under load. (do I even understand this weird thing correctly?). I also am concerned that you are measuring from the correct reference surfaces but I think you understand that correctly.

[bmwmick]

Correcting this misalignment shouldn’t be all that difficult. The transmission housing would need to be shifted up by the corresponding amount. I would probably plug the two locating holes in the transmission casing then bore and ream them to size in the correct location. Since the offset is so small, I could probably just bore out the four remaining transmission bolt holes to accommodate the move.

 

Question is though; is all this really worth it for a measly eleven thousandths of an inch?

 

Derek,

Looking at your dial indicator, if I'm looking at the rear of the intermediate housing with your plate bolted up, it appears the engine output shaft is 0.011" LOW? That would mean you will have to LOWER the transmission in relation to the engine output shaft, not RAISE it.

 

How difficult would it be to make some offset dowels rather than fill and re-drill the mounting holes? I used to use these offset bushings to get the timing advanced or retarded when I zero'd the cam on my small block Chevys. You could leave the front half of the alignment dowel stock and offset the circumfrence of the back half that locates the tranny. The rest of the tranny bolt hole might already have enough slop in them to accomodate the 0.011" offset you need........just a thought.

 

Mick

[matanuska]

...(do I even understand this weird thing correctly?)...

 

Niel - I'm with you there, this whole thing is making my head hurt too!

 

Yes, you're right about the engine output shaft being a separate jackshaft, gear driven from the crank. I've checked and it doesn't seem to have any excessive play. I'm also encouraged to see that the magnitude of my measured offset is consistent with that found in the other spline thread currently on the Oilhead forum. This lends credence to the theory of some type of random manufacturing error. Maybe the German CNC operator was a little hung-over from a good Oktoberfest party the day these parts were made!

 

DR

[matanuska]

Looking at your dial indicator, if I'm looking at the rear of the intermediate housing with your plate bolted up, it appears the engine output shaft is 0.011" LOW? That would mean you will have to LOWER the transmission in relation to the engine output shaft, not RAISE it.

 

How difficult would it be to make some offset dowels rather than fill and re-drill the mounting holes? I used to use these offset bushings to get the timing advanced or retarded when I zero'd the cam on my small block Chevys. You could leave the front half of the alignment dowel stock and offset the circumfrence of the back half that locates the tranny. The rest of the tranny bolt hole might already have enough slop in them to accomodate the 0.011" offset you need........just a thought.

Mick,

 

See above, this whole thing makes me dizzy! Yes, you’re right, I’ve double checked my work several times and had others provide peer checks. The tranny needs to move down with respect to the engine output shaft. That agrees with what I observed before when I could tilt the tranny casing down (opening the .025” gap) and my go/no-go gauge would fit.

 

I’ve debated several ways to correct the problem – offset pins, drill and offset the holes, etc. Each has its advantages and disadvantages. Some require accurately locating the center of the present holes, calculating offsets, drilling & reaming, etc. However, final alignment will be determined upon the accuracy of the calculations and any errors in locating the new holes. Same with the offset pins – final alignment is going to be determined by indirect calculations and fabrication tolerances of the pins.

 

However, since I’m shooting for absolute perfection here (remember my OCD) I’ve decided the cleanest way is to remove the old pins allowing me to freely adjust the two shafts to absolute dead nuts alignment using the indicator and bolt the tranny and intermediate flange together. Then I can put the whole assembly up on the Bridgeport and drill/ream/pin them in place in one shot with no doubt that the alignment is correct.

 

DR

[bmwmick]

Sounds like the best solution since you have the tool to do it!

Us mere mortals would probably opt for an easier fix.

Mick

[sb955i]

This is a very interesting thread to follow I must admit. I'm wondering, if there's barrel-shaped wear on the input shaft, is it possible that there is :

 

1) housing flex under load

2) previously inaccurately torqued housing studs allowing flex

3) housing mating surfaces curved in one plane to allow it to rock, producing a logitudinal difference under load , or when unloaded.

 

It would be a shame to correct any planar intolerances through alignment changes, when flex is/was the culprit.

 

I'll butt-out now.. i'm an IT guy after all