How do you measure for proper transmission alignment?

[Willie]

So this is an add on thread to my clutch replacement post. It seems most (if not all) on the forums have found an actual misalignment between the trans and engine, while the rare few believe that the problem may be inside the transmission or in the clutch assembly. My trans is off being rebuilt now, so I am assuming the internal will be good to go. I am still debating how far I want to go with replacing the clutch parts. I at least need the friction disk and new bolts and per the trans builder, should get a diaphragm spring, pressure plate, and outer housing cover. He beleives that this would help with any alignment problems also. Anton believes this too, but also with a flywheel replacement.

 

Now, for those that measured the alignments, how did you do it and what was done to solve the problem. I think Dirtrider said that he made some off set mounts to correct the problem. I never did anything like this before, but have a friend that is pretty handy in his garage machine shop. If I knew the procedure and could explain it to him, he might have the tools to read the off set and possibly be able to make some shims to align the mount.

 

I am confident the trans will come back in fantastic working order. I KNOW there is an alignment problem. I'm just not willing to throw extra money at clutch parts ASSUMING that this will fix it. I value the word of people that do this for a living, but unless I know THEY will foot the bill for the next rebuild, I need to know more about what I am doing.

 

Any help, especially with pics, would be great! I need to do something to get piece of mind about this repair other than just replacing with new clutch parts. Thanks

[dirtrider]

Morning Willie

 

 

I don’t have a lot of time to at the moment to fully detail checking the trans to engine alignment. (I’m supposed to be in a meeting about 5 minutes ago)

 

Basically you need to stop the trans rebuild RIGHT NOW. As you need to get the trans front housing back to do the measurements with. Without that front trans housing there’s no need to even peruse this any farther as there is no way to measure anything worth while.

 

In a nut shell—You need to make up a simple mounting stand to bolt to the rear of the crankshaft, then bolt the old trans front housing on the engine with your mounting stand extending through the front bearing bore, then set up a dial indicator on the front housing bearing bore to allow the crankshaft to bearing bore to be swept with the indicator. That will show any misalignment.

 

If it is off center then remove the trans front housing & re-install with no housing to engine block alignment pins. Then with slightly loose mounting bolts move the housing around until the bearing is perfectly centered on the rotating crankshaft.

 

Then make up new (off set) alignment pins to PERMANENTLY move the front housing to that position.

 

[Willie]

Well, the guy is might be into the trans already as he's had it for a week now and it needs rebuild anyway, right? Can't the rear of the block be measured to make sure that the crank/flywheel is spinning true to the mounting surface? Then can't the front mounting surface be measured off the input shaft to make sure that that is true on the trans? If there is a variation, is there a way to us peel washers or something to shim the proper mounting bolts the proper direction to align the mounting of the trans? Again, I know nothing of this type of thing and appreciate the help.

[nrp]

Willie - No you must get to the transmission input bearing housing bore to measure the run out as the crank is rotated (unless you want to tear the engine apart and measure the main bearing bore while rotating the transmission input shaft)

 

One thing you can do - Measure the clearance in the rear main bearing by using a dial indicator on the flywheel that's mounted on the block. Measure it in both directions. I found that the rear main will wear in the direction of any radial misalignment. The rear main bearing radially loads against the transmission input bearing as the misalignment drags the clutch disc around on the flywheel face. The one I looked at had .007 inch main bearing clearance in the 10 o'clock/4 o'clock direction.

 

I have pictures someplace - will post later.

[dirtrider]

-----Can't the rear of the block be measured to make sure that the crank/flywheel is spinning true to the mounting surface? Then can't the front mounting surface be measured off the input shaft to make sure that that is true on the trans?

 

 

 

Sure, given enough time to machine up a proper fixtures and lots & lots of setup time. There really isn’t anything concentric enough on the engine block or the trans housing to do this without great effort, copious amounts of time, precision machine work time, and even then the results will be less accurate than just using the original front trans housing. Technically the answer is yes--Practically the answer has to be a no.

 

-----If there is a variation, is there a way to us peel washers or something to shim the proper mounting bolts the proper direction to align the mounting of the trans? Again, I know nothing of this type of thing and appreciate the help.

 

No, nothing like peel washers or shims. It is actually pretty simple as ALL you really need is proper offset to the alignment pins. The difficult part is knowing how much & where to offset to.

 

 

I will tell you up front that if you are unwilling to retrieve the trans front housing then probably just give up on the idea of checking or aligning the trans to engine.

 

Personally if I was going to put that back together without measuring anything I would at least install a new replacement front trans housing on the trans as he rebuilds it. That doesn’t guarantee a proper alignment but the chance of the problem being in that part is probably greater than other areas.

 

One thing I can do is predict your spline failure issue will return (IF) you just put it back together with the original trans housing, original clutch parts, & original flywheel.

 

 

 

[Willie]

I'll see how far he got. Are you talking about a brand new ($500) front housing or just a "different" one?

[OoPEZoO]

Willie - No you must get to the transmission input bearing housing bore to measure the run out as the crank is rotated (unless you want to tear the engine apart and measure the main bearing bore while rotating the transmission input shaft)

 

One thing you can do - Measure the clearance in the rear main bearing by using a dial indicator on the flywheel that's mounted on the block. Measure it in both directions. I found that the rear main will wear in the direction of any radial misalignment. The rear main bearing radially loads against the transmission input bearing as the misalignment drags the clutch disc around on the flywheel face. The one I looked at had .007 inch main bearing clearance in the 10 o'clock/4 o'clock direction.

 

I have pictures someplace - will post later.

 

Interested to see those pics. The engine from my RT is sitting in the middle of my garage on a piece of plywood right now. I would be really curious to recreate the setup you used so I can take some numbers and compare.

[dirtrider]

Are you talking about a brand new ($500) front housing or just a "different" one?

 

 

 

Willie

 

Yes & yes. If you can find a good used one that centers up properly then no reason to spend big bucks on a new. The problem is a used can be just as bad or worse than yours is (especially if it is for sale due to a similar alignment problem) . At least new gives you a fighting chance that it will center up properly.

 

But there is probably nothing wrong with your front housing (IF) you can get it back & take the measurements then move it to proper aligned center.

 

Your other option is to just install the rebuilt trans then ride it as installed for 10,000-15,000 miles then trade your bike in on a new bike. Not that they couldn’t fail earlier but I haven’t seen one fail at less that 22,000 miles so far.

 

[Willie]

The last option is sounding like the best for me. I only have 32k on this one, and it didn't actually fail, so I'm hoping it would last at least that long, but all of this is only a gamble anyway. I'm so fed up at this point, that if I can get the trans back, I just might put a new clutch disk in and put it back together for a trade in like I originally was going to do anyway, before I actually pulled the trans out to see what was going on. I can never make up my mind about anything that costs me money. Ask my wife The problem is that I can't find a bike that does what my RT does the way I like it...

[nrp]

At least check the rear engine main bearing clearance with a dial indicator. If it happens to be unusually loose (like more than say .003 inch), the alternating piston forces will pound hell out of the spline.

[RT Russ]

I'll see how far he got. Are you talking about a brand new ($500) front housing or just a "different" one?

 

I'm in the middle of the same ordeal. When the shop suggested looking for a used ront cover, I demanded a new cover. How would I know if a used cover would not have an alignment issue. Further......how do I know that a new cover from BMW won't have the alignment issue?

[Willie]

I'll see how far he got. Are you talking about a brand new ($500) front housing or just a "different" one?

 

I'm in the middle of the same ordeal. When the shop suggested looking for a used ront cover, I demanded a new cover. How would I know if a used cover would not have an alignment issue. Further......how do I know that a new cover from BMW won't have the alignment issue?

 

You don't know. That's the real rub here. If everyone said replace part X with part Y and the problem would be solved, I'd pull out the wallet, put on the part and sleep well at night. Very few options here and I feel like I'm already putting too much in here moneywise.

[Phil50]

Is this specifically a 2002 R1150** (ie pre twin spark) issue?

 

 

[dirtrider]

Is this specifically a 2002 R1150** (ie pre twin spark) issue?

 

 

Afternoon Phil

 

Pretty well, ALL 1150’s seem subject to the spline failure but the 2002’s seem to have the most issues (at least reported issues).

 

Not sure if it due to the parts aligning better due to better quality control in the later 1150’s or the later 1150 twin spark engines have smoother firing pulses or just plain luck.

 

 

[Phil50]

Evening DR,

 

After reading this thread and posted that questionI got interested and did a bit of reading around. I read somewhere, I think advrider, that this was caused by a problem batch of trans boxes on 2002 bikes. Does that sound right?

 

Cheers

 

Phil

[Stan Walker]

There are more '02s. They were sold for almost 2 years starting in Apr 01. Also it was the first year of a new model run.

 

Stan

 

[nrp]

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

These are pictures of my engine-transmission alignment measurement test fixture. It mounts magnetically on three flywheel bolts with a small weldment, and a standard dial test indicator from Harbor Freight or equal (about $25 as I recall). It is a little futzy to set up, but the same setup allows the evaluation of the engine main bearing clearance.

 

I built this fixture as any traditional machinists mag base etc assembly wouldn't fit in the narrow confines of the housing and would have too much deflection for an accurate measurement.

 

I used a couple of old hard drive super magnets to fasten the fixture to three flywheel bolts, and let the dial indicator tip run on the bearing housing OD. Measurments can be taken in one sweep of the crankshaft and should be less than perhaps .003 inch TIR. In addition I measured the backlash in the rear crankshaft bearing where I was surprised to find over .007 inch clearance Should be less than ~.002) in the 10 o'clock/-4 o'clock direction. This just happened to corresponded to the .012 inch run out direction I found between the crank rotation axis and the input bearing housing axis.

 

This excessive main bearing clearance means the main bearings are worn in a strange direction. The lateral crankshaft loads generated by the pistons end up being reacted across the spline beating hell out of the transmission input bearing (which has much less radial clearance) as well as the spline. I presume the main bearing wear was caused by the initial transmission misalignment. That's why it should be checked in any reassembly as wear in the mains can also wreck a spline system - even with a good housing and transmission.

 

Now I gotta figure out how to post pictures from my earthlink website.......

 

FWIW - I still have the fixture & could send it to someone that would use it. PM me.

[Willie]

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

These are pictures of my engine-transmission alignment measurement test fixture. It mounts magnetically on three flywheel bolts with a small weldment, and a standard dial test indicator from Harbor Freight or equal (about $25 as I recall). It is a little futzy to set up, but the same setup allows the evaluation of the engine main bearing clearance.

 

I built this fixture as any traditional machinists mag base etc assembly wouldn't fit in the narrow confines of the housing and would have too much deflection for an accurate measurement.

 

I used a couple of old hard drive super magnets to fasten the fixture to three flywheel bolts, and let the dial indicator tip run on the bearing housing OD. Measurments can be taken in one sweep of the crankshaft and should be less than perhaps .003 inch TIR. In addition I measured the backlash in the rear crankshaft bearing where I was surprised to find over .007 inch clearance Should be less than ~.002) in the 10 o'clock/-4 o'clock direction. This just happened to corresponded to the .012 inch run out direction I found between the crank rotation axis and the input bearing housing axis.

 

This excessive main bearing clearance means the main bearings are worn in a strange direction. The lateral crankshaft loads generated by the pistons end up being reacted across the spline beating hell out of the transmission input bearing (which has much less radial clearance) as well as the spline. I presume the main bearing wear was caused by the initial transmission misalignment. That's why it should be checked in any reassembly as wear in the mains can also wreck a spline system - even with a good housing and transmission.

 

Now I gotta figure out how to post pictures from my earthlink website.......

 

FWIW - I still have the fixture & could send it to someone that would use it. PM me.

 

I know Keith and myself would get some use out of it if you're so inclined Hope Keith doesn't mind me speaking for him...

[dirtrider]

Evening DR,

 

After reading this thread and posted that questionI got interested and did a bit of reading around. I read somewhere, I think advrider, that this was caused by a problem batch of trans boxes on 2002 bikes. Does that sound right?

 

 

Phil

 

Only BMW knows for sure & they sure aren’t talking. Problem is, most cases are limited to the very few failed bikes a person actually works with or the specific model year a person owns & has issues with.

 

I had a 2002 RT & sold it a few years back, the new owner has been all over the country and last I knew has just short of 100,000 miles on it still with the original clutch & original trans splines. Obviously that 2002 didn’t have a bad transmission alignment. I put a final drive crown bearing in that bike and shimmed the preload well before I sold it and that is still doing good also.

 

Not ALL failures are the 2002 bikes but they seem to account for more than their share.

 

If you do some research you will find that 2002 seems to have the most issues but as Stan said BMW sold a lot of that year in that model.

 

I do know early on there were very few European failures & many more US failures so there was a lot of speculation at one time it had something to do with the way the bikes were supported during shipment to the US. I haven’t ever seen any follow up to that so it might just be wishful thinking on that reason for failure.

 

[OoPEZoO]

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

These are pictures of my engine-transmission alignment measurement test fixture. It mounts magnetically on three flywheel bolts with a small weldment, and a standard dial test indicator from Harbor Freight or equal (about $25 as I recall). It is a little futzy to set up, but the same setup allows the evaluation of the engine main bearing clearance.

 

I built this fixture as any traditional machinists mag base etc assembly wouldn't fit in the narrow confines of the housing and would have too much deflection for an accurate measurement.

 

I used a couple of old hard drive super magnets to fasten the fixture to three flywheel bolts, and let the dial indicator tip run on the bearing housing OD. Measurments can be taken in one sweep of the crankshaft and should be less than perhaps .003 inch TIR. In addition I measured the backlash in the rear crankshaft bearing where I was surprised to find over .007 inch clearance Should be less than ~.002) in the 10 o'clock/-4 o'clock direction. This just happened to corresponded to the .012 inch run out direction I found between the crank rotation axis and the input bearing housing axis.

 

This excessive main bearing clearance means the main bearings are worn in a strange direction. The lateral crankshaft loads generated by the pistons end up being reacted across the spline beating hell out of the transmission input bearing (which has much less radial clearance) as well as the spline. I presume the main bearing wear was caused by the initial transmission misalignment. That's why it should be checked in any reassembly as wear in the mains can also wreck a spline system - even with a good housing and transmission.

 

Now I gotta figure out how to post pictures from my earthlink website.......

 

FWIW - I still have the fixture & could send it to someone that would use it. PM me.

 

I know Keith and myself would get some use out of it if you're so inclined Hope Keith doesn't mind me speaking for him...

 

Speak away buddy.......not that I really care at this point about my motor. For all intents and purposes it is Ebay fodder. That being said, I am still curious.

[AndyS]

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

any luck on showing us those pictures of your fixture?

 

 

[AndyS]

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

Couldn't your measurement system be wrong? you are measuring the lip of the counterbore into which is pressed the rear crankshaft oil seals? However the main bearings are on a different diameter further into the rear crankcase housing , so you may be just measuring eccentricity of the oil seal housing (which indeed could propogate a leak), but doesn't prove misalignment - does it?

... In addition I measured the backlash in the rear crankshaft bearing where I was surprised to find over .007 inch clearance Should be less than ~.002) in the 10 o'clock/-4 o'clock direction.

...This excessive main bearing clearance means the main bearings are worn in a strange direction.

Are you saying that your main bearings are loose in their housing?

or are you saying that the main bearing is worn - giving you this 'backlash'?

Andy

[AndyS]

Sorry disregard the post above, I screwed up the edit in the above post and put my question to nrp actually within his post.

This is how I would like the post to read, I was asking nrp the following:

 

Who says the problem is in the front cover? It possibly is but that is a questionable assumption.

 

... In addition I measured the backlash in the rear crankshaft bearing where I was surprised to find over .007 inch clearance Should be less than ~.002) in the 10 o'clock/-4 o'clock direction.

...This excessive main bearing clearance means the main bearings are worn in a strange direction.

 

Couldn't your measurement system be wrong? you are measuring the lip of the counterbore into which is pressed the rear crankshaft oil seals? However the main bearings are on a different diameter further into the rear crankcase housing , so you may be just measuring eccentricity of the oil seal housing (which indeed could propogate a leak), but doesn't prove misalignment - does it?

 

Also, are you saying that your main bearings are loose in their housing?

or are you saying that the main bearing is worn - giving you this 'backlash'?

Andy

[Willie]

nrp's pics... Cool little setup.

 

[nrp]

My concern is that there is that the rear main crankshaft bearing shell is worn on its ID due to the indeterminate loads applied to it by the transmission input shaft misalignment. It is a quick item to check if a dial indicator is handy. An experienced mechanic could probably can even judge it just by feel. Note though that the main bearing ID can be egg shaped in any direction depending on the misalignment error axis.

[AndyS]

Hi NRP, I am still failing to see how putting a Dial gauge onto the flywheel, and then running the gauge tip around the gearbox input shaft bearing housing would show up a worn engine rear main bearing?

The engine is not under load when performing this test and so even if the main bearing were worn, it would give a very variable reading. moreover if the rear main bearing was that worn, surely the oil pressure would be way down and the engine would be due for expiry very soon?

Andy

[wheeliepup]

I think he's measuring the alignment between the transmission input (splined )shaft and the engines crank shaft. Your right about the bearing ... dial gauge is not much help there!

[nrp]

Hi AndyS -

 

It isn't necessary nor intended to rotate the crank during this second test - except to reposition it 90 degrees (approx) to determine which axis best defines any egg shapeness of the crankshaft main bearing clearance.

 

I just gently pried the flywheel up & down (using a blade screwdriver I recall) with the indicator measuring vertical travel at the transmission bearing housing ID, then repeating the test in the horizontal axis. It isn't necessary to measure with respect to anything in particular, just to get an idea of the main bearing clearance. I recall that I started on this tack just by casually prying the flywheel & noting what seemed like excessive lash in the crankshaft bearing system, Hmmmmmmm......

 

I was surprised at the variation in clearance - and the direction of the greatest egg-shaped motion. I could understand a clearance increase in the cylinder axis direction due to firing forces. It happened the egg shape axis corresponded to the clutch housing (or whatever) alignment error measured earlier.

 

Main bearings should have less than about .002 clearance, or otherwise the rear piston loads will be transferred across the spline to the transmission input bearing, neither of which can handle that much force. Apparently the crankshaft main bearing can't handle the force required to slide the clutch disk around the flywheel either if there is a disagreement on the rotation axis..

[OoPEZoO]

Gottcha, now I see what you are measuring. I thought you were spinning the crank and taking a measurement, but couldn't wrap my head around how you were getting anything accurate enough to trust.

 

I may be able to recreate this with my motor without the front cover of the transmission. its certainly worth at least playing with it for an hour to see what I can see.

[dirtrider]

 

 

That seems like a strange way to verify rear main bearing running clearance.

 

With that dial indicator out on a lever arm then prying on the flywheel, that will magnify the rear crankshaft movement over the length of the lever arm unless the entire crankshaft moves up & down the exact same distance over it’s entire length (highly unlikely as you were only prying on the flywheel end).

 

That method will definitely show crankshaft movement but I doubt it is accurate as far a usable bearing clearance is concerned. The wear limit on the 1150 rear bearing is .0039” (almost .004”) in the cross engine direction & that is measured using precision micrometers on the crankshaft & bearing bore.

 

I guess my question has to be why only on the 1150’s. I have seen high mile 1100’s with large amounts of rear bearing running clearance and absolutely no trans input spline wear.

 

[JamesW]

Was going to keep my mouth shut but I can't help it. I think the main cause of spline wear has to do with the way these bikes are ridden. If the problem was caused by poor quality control then why are European models not affected? I think it is mostly due to the 6 speed trans and way too many bikes being ridden in 6th at slow speed. These bikes are not Harleys (thank god) and should not be ridden as if they were. I never use 6th on my '04RT unless I can ride at 80 mph or higher. I always shift at 4500 revs or higher. Pulled my trans last fall just to check splines and no wear whatsoever. Spline wear was a problem on the R100's caused by soft spline metal primarily and that issue was addressed years ago. Long and short is forget 6th gear and wind 'em out. That doesn't mean you do 9 second quarter mile starts at every stop light either, but just keep those revs up.

[nrp]

 

That seems like a strange way to verify rear main bearing running clearance. It beats tearing the engine apart though....

 

With that dial indicator out on a lever arm then prying on the flywheel, that will magnify the rear crankshaft movement over the length of the lever arm unless the entire crankshaft moves up & down the exact same distance over it’s entire length (highly unlikely as you were only prying on the flywheel end). Correct - it will magnify the clearance but it should still be a valid evaluation of the ovality of the main bearings.

 

That method will definitely show crankshaft movement but I doubt it is accurate as far a usable bearing clearance is concerned. The wear limit on the 1150 rear bearing is .0039” (almost .004”) in the cross engine direction & that is measured using precision micrometers on the crankshaft & bearing bore. Probably most easily measured with Plastigage. A dial indicator could also be used although you are correct that the geometery should be considered before selecting any different bearing shell diameters. A .004 inch main bearing clearance will be pretty noisy & I would guess that it would help pound the clutch hub spline quite badly given the stiffness of the rest of the force path and transmission input shaft bearing. My point is that this may originate as a misalignment problem, but that its complete solution should also involve evaluating the crankshaft main bearing system to avoid another premature failure.

 

I guess my question has to be why only on the 1150’s. I have seen high mile 1100’s with large amounts of rear bearing running clearance and absolutely no trans input spline wear. My crank bearing ovality measurements were on an 1100RT, and the fixture pictured above is specific to the R1100. I don't know if the 1150 can use the same fixture but at least I think the concept of a comparatively rigid custom fixture based on rare earth magnets from a hard drive is the best way to measure misalignment in the event of a spline failure.

[Boffin]

Was going to keep my mouth shut but I can't help it. I think the main cause of spline wear has to do with the way these bikes are ridden. If the problem was caused by poor quality control then why are European models not affected? I think it is mostly due to the 6 speed trans and way too many bikes being ridden in 6th at slow speed. These bikes are not Harleys (thank god) and should not be ridden as if they were. I never use 6th on my '04RT unless I can ride at 80 mph or higher. I always shift at 4500 revs or higher. Pulled my trans last fall just to check splines and no wear whatsoever. Spline wear was a problem on the R100's caused by soft spline metal primarily and that issue was addressed years ago. Long and short is forget 6th gear and wind 'em out. That doesn't mean you do 9 second quarter mile starts at every stop light either, but just keep those revs up.

 

The European models are affected - Steve1962 is currently awaiting a rebuild of his tranny to fix dead splines. This forum is predominantly US based so you do not see so many posts from Europe - especially as most of Europe is non-English speaking.

 

Andy

[NonComp]

Was going to keep my mouth shut but I can't help it. I think the main cause of spline wear has to do with the way these bikes are ridden. If the problem was caused by poor quality control then why are European models not affected? I think it is mostly due to the 6 speed trans and way too many bikes being ridden in 6th at slow speed. These bikes are not Harleys (thank god) and should not be ridden as if they were. I never use 6th on my '04RT unless I can ride at 80 mph or higher. I always shift at 4500 revs or higher. Pulled my trans last fall just to check splines and no wear whatsoever. Spline wear was a problem on the R100's caused by soft spline metal primarily and that issue was addressed years ago. Long and short is forget 6th gear and wind 'em out. That doesn't mean you do 9 second quarter mile starts at every stop light either, but just keep those revs up.

Now I can't keep my mouth shut. There are well documented cases on this forum of owners with failures in as little as 7k miles (the one that I am thinking about was a poor fellow who bought a 2002 RT with no miles on it that had been garaged for years. Splines failed at about 7600 miles if I remember correctly. Others have reported two or three failures at regular intervals, often at 12-15k miles.

 

So, are you suggesting that BMW input shafts are so fragile that lugging the engine for 7 to 15k miles will cause spline failures? Since the majority of failures seem to occur on 2002 models, does that mean that more 2002 owners lug their bikes more than others? Or are there more 2002s out there, so the proportion of failures = the proportion of luggers in any given model year? Doesn't make sense.

 

More idle speculation: Now that BMW is having all their gearboxes built on contract in India, perhaps the QA will a)improve or b)get worse (pick one).

[dirtrider]

Afternoon James

 

No doubt that lugging could contribute to a spline wear issue but then why so many spline failures even on the GS with lower gear ratios or why more 2002 spline issues than the later 03-04 1150’s ? Why not many 1100’s as I’m sure those things were also lugged around in too high of a gear for their speed.

 

Also why do a lot of the people that seem to repair these things so the problems don’t return find trans-to-engine alignment issues. Anton seems to have a pretty good understanding of the spline wear issue as and has worked on quite a few. Seems he is seeing alignment issues on the failures he has worked with.

 

I have seen quite a number of car & truck trans spline wear issues from lugging and in almost all cases the spline wear is even across the full spline length at the clutch disk contact area. If you look at the 1150 spline wear it is usually quite angular along the length of the spline so that says the clutch disk is not straight on the splines during the wear process.

 

[nrp]

If you look at the 1150 spline wear it is usually quite angular along the length of the spline so that says the clutch disk is not straight on the splines during the wear process.

The only requirement for the spline OD and ID is that all tangential surfaces have to carry load in the presence of micro fretting. The weird patterns are the result of slight differential hardness of the two elements. The spline OD may look spiraled, but I'll bet anything that if you look critically at the mating ID spline, that it will be curved in a complementary matching direction also.

 

It is easy to be fooled into thinking that the curved/slightly-spiral shape of worn splines is due to angular misalignment between the engine and the transmission. Really though the surfaces only have to be conjugal (guess on the meaning of that!)

 

There are also those that feel that if the spline were only a little longer and projected into the clutch disk a little more, that it would somehow last. I can assure you that would only be incrementally so.

 

A spline is an internal tooth gear running on an external tooth gear - of one to one ratio. The spline surfaces are cut like gears - and are generated in a curved profile like gear teeth. (OK the ID spline is broached but the broach is a generated surface too.)

 

Ideally the individual teeth only would carry the torque loads but since they may be running on slightly different center lines, they also forced to slide back and forth with respect to each other in a micro-manner that causes localized seizing - unless there is a lubricant present. Any lube will eventually be forced out of the interfaces and that's when the rust particles from fretting corrosion will begin to come out of the spline.

 

That's why an ongoing spline inspection thru the starter port may be an easy way to evaluate any potential alignment and wear problems.

[Willie]

A peak behind the starter is a good idea, but you would only be able to track the play of the clutch disk rotating around the input shaft I believe. I don't think you would be able to see the point of the input shaft that wears.

On a side note, a car mechanic buddy was over and I showed him my clutch disk splines. The tranny is off being fixed so I wasn't able to show him that. Anyway, with him not knowing about the BMW drivetrain, he firstly couldn't believe that the input shaft didn't go the whole way into the disk. Secondly, the fisrt cause of wear that he thought of the faulty heat treat or differing heat treats or metal hardness between the two parts.

Like I said, this was his take on it not being familiar with any of this stuff being discussed. I did see on the net that someone makes an aftermarket input shaft that goes the whole way into the clutch disk and is heat treated differently, but the shaft itself is the same cost as my whole trans getting fixed. I guess if it actually is an alignment issue, a longer, more expensive shaft wouldn't be the way to go anyway.

[dirtrider]

 

Evening NRP

 

Obviously until total failure the internal clutch disk internal splines will pretty well mirror the wear pattern on the OD of the input shaft.

 

I guess the point I failed to get across is that I have see a fair amount of car & truck input shaft spline wear in different phases of wearing (seldom a total failure like on the BMW) and those are worn way more evenly along the length & face of the splines.

 

Based on other automotive spline wear I have seen if all is aligned properly with the trans input shaft being centered on the crank I would expect see the wear more evenly spread all along the disk to input shaft spline contact area not so localized as shown.

 

 

[nrp]

I think you might be looking at a more consistent hardness profile in automotive etc applications. Not necessarily more equal, just happened to be more matched.

 

They also nylon coat many splines to minimize fretting. Those splines that are at the end of an extended shaft would also be more tolerant of minor radial misalignment in that the shaft can simply flex slightly to accommodate errors. Nylon (and Delrin) is very effective at needing only the tiniest quantity of oil for long life.

 

The BMW M/C splines are unusually close coupled to the supporting bearings making the application more sensitive to misalignment. The male spline is not nylon coated for whatever reason. It might be a cost or even a heat issue.

[JamesW]

Hi D.R.,

I hear what you are saying but i just can't believe BMW would have a QA issue of this magnitude and if they did not fess up. What year was the 6 speed trans introduced and when was the engine bumped up to 1150 cc ? Both of these mods could exacerbate the problem when combined with the rocking couple vibes produced by the flat twin add to that a tendency to operate at low RPM and what do you get? Also, I have never seen a follow up thread about the results of changing the trans housing. Just seems to me there are missing peaces to this puzzle. Yup, the wear pattern shown in your pix is strange. You would think it (wear) would be more linear. Thank heavens my splines are OK.

[AndyS]

Gottcha, now I see what you are measuring. I thought you were spinning the crank and taking a measurement, but couldn't wrap my head around how you were getting anything accurate enough to trust.

.

 

Hi Keith, I don't think I have got what nrp is trying to show me. I can see how his measurement would show gearbox misalignment when he rotates the flywheel he would see the measurable offset of the crankshaft axis with respect to the gearbox - that's good. But I don't see how he is measuring main bearing wear using this method.

 

Andy

[OoPEZoO]

Gottcha, now I see what you are measuring. I thought you were spinning the crank and taking a measurement, but couldn't wrap my head around how you were getting anything accurate enough to trust.

.

 

Hi Keith, I don't think I have got what nrp is trying to show me. I can see how his measurement would show gearbox misalignment when he rotates the flywheel he would see the measurable offset of the crankshaft axis with respect to the gearbox - that's good. But I don't see how he is measuring main bearing wear using this method.

 

Andy

 

I'm not interested in exact measurments of the main bearing. I'm just interested to see if there is any slop, and if there is........is it uniform around the circumference, or is it oblong in any direction. To be honest, at this point I'm not sure I even care. The only reconizable part left of my RT is the motor, and that is sitting on a piece of plywood in the garage. The rest is "neatly scattered" around the garage awaiting me to write up for sale listings. I would like to know the root cause that was the demise of my RT, but at this point I'm kind of losing interest. Trying to debate between taking precise measurements on a 126k mile motor or taking my new 1200GS out for a spin.......hmm, pretty sure the GS is going to win that every time.

[nrp]

But I don't see how he is measuring main bearing wear using this method.

 

Andy

I'm just measuring the bearing clearance in a couple of directions using the same setup using a small prybar on the flywheel. There are a lot of ways the bearing clearance can be measured, but this takes only a few seconds. I did it in a couple of directions to verify how the bearing shells were worn.

[nrp]

Keith - can you gently pry on the flywheel & "measure" the bearing backlash with your finger? In the example I worked on it was quite obvious. Tight this way, loose that way........

[OoPEZoO]

I'm going to give it a look.......I've just been way too busy the past few days.

[NonComp]

I hear what you are saying but i just can't believe BMW would have a QA issue of this magnitude and if they did not fess up. What year was the 6 speed trans introduced and when was the engine bumped up to 1150 cc ? Both of these mods could exacerbate the problem when combined with the rocking couple vibes produced by the flat twin add to that a tendency to operate at low RPM and what do you get? Also, I have never seen a follow up thread about the results of changing the trans housing. Just seems to me there are missing peaces to this puzzle. Yup, the wear pattern shown in your pix is strange. You would think it (wear) would be more linear. Thank heavens my splines are OK.

I believe that the 1150 with 6-speed was introduced in Europe in 2001 and in the US in 2002, and these have had the most reported failures.

 

BMW has a history of remaining aloof when it comes to non-safety related design problems. There have been cases before and after (the M94 gearboxes on the 1100s in the 90's and final drive failures on the early 1200's, as two examples) that were dealt with in the same fashion - ie. on a case-by-case basis under warranty. In the case of premature spline failures, dealers have been known to install new parts without investigating the cause, resulting in additional periodic failures.

 

Perhaps the reason that successes are not reported is that, when your bike stops breaking, you are less likely to get on the forum and complain about it.