Checking for spline wear 1999 R1100S

The wear pattern on the shaft, with its curved shape remains very telling. I like Anton's solution of replacing the shaft and all clutch parts, which he says from experience works. Here's why it makes sense to me.

Looking at the clutch disk, it has 5 flexible arms. This helps the clutch system to accommodate any clutch disk planarity issues. Setting aside misalignment for a moment, almost any of the parts of the clutch system could produce an error in planarity with the clutch disengaged. When fully engaged, the housing covers control final planarity, which replacing the clutch pack would resolve as Anton says in 99.x% of cases.

Fully engaged, a planarity error puts a load on the input shaft that could cause wear.

As you engage the clutch, the load from a planarity error will progress radially around the shaft until all surfaces and shafts are moving at the same speed, in a sort of wobble. Try and imagine what that would do if the shaft to hub engagement were less than it is.

Either fully or partially engaged, once wear begins if there is a planarity error, it's not hard to imagine wear accelerating.

So I think I'd take Anton's approach which uses available parts and doesn't require an alignment analysis and repair. Then, myself, I'd take the added step of a Bruno's extended hub (since GSAddict's shaft isn't available) for full engagement to reduce any tendency of a planarity error to progress during engagement or wobble with wear.
RB

roger 04 rt said:

..............Fully engaged, a planarity error puts a load on the input shaft that could cause wear...................

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I'm not sure what you mean by a "planarity error". Do you mean an angle between the transmission vs engine axes? or do you mean a radial discrepancy between those two axes?

I contend that these failures are caused by a small radial discrepancy that is making the transmission shaft drag the engaged clutch disc around the flywheel face - every revolution.

There is no easy way to measure the radial discrepancy except to make a fixture & dial indicate to the inside of a disassembled transmission case.

Assuming that there are no radial or axial alignment errors of the shaft centerlines, by planarity I'm referring to the clutch housing, and/or the unloaded clutch disk being in a purely square-radial plane to the engine and transmission shaft centerline. That is the issue I'm commenting on in my last post. There may be a better term for what I'm describing.

Torsional whip

Read this article and look at the effects on the splines. Very similar to our problem.
Keep in mind in the oilhead case the damping is past the input shaft splines inside the transmission. (unsprung clutch)
I'm wondering about the "buzziness" @ 4000 rpm being the harmonic that causes the most wear


http://www.jackstransmissions.com/pages/keep-your-balance-shafts

GSAddict said:

Read this article and look at the effects on the splines. Very similar to our problem.
Keep in mind in the oilhead case the damping is past the input shaft splines inside the transmission. (unsprung clutch)
I'm wondering about the "buzziness" @ 4000 rpm being the harmonic that causes the most wear


http://www.jackstransmissions.com/pages/keep-your-balance-shafts

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Don't know if anyone has pointed to this sight yet: www.rbracing-rsr.com I found this sight several years ago and saved it for future reference just in case, scroll down to about midway in this link to the section on BMW clutches. At about 36K miles I did a spline lube/inspection on my '04RT and found splines to be pristine with absolutely no wear. It is interesting what Anton says about spline issues mainly having to do with the 6 speed trans models. The way I have ridden my bike since new is to hardly ever use 6th gear and I wonder if this mode of operation has contributed to negligible spline wear. Since installing a wideband O2 sensor with LC-1 which resulted in a much improved low end power output I have found 6th gear much more usable but I can't help but wonder what increased 6th gear use will over time mean for the trans input shaft splines. Hmmmmm...

I am curious, are there any high mileage 1150's that DON'T exhibit this wear pattern?

GSAddict said:

Read this article and look at the effects on the splines. Very similar to our problem.
Keep in mind in the oilhead case the damping is past the input shaft splines inside the transmission. (unsprung clutch)
I'm wondering about the "buzziness" @ 4000 rpm being the harmonic that causes the most wear


http://www.jackstransmissions.com/pages/keep-your-balance-shafts

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Interesting, but I do not find this torsional whip idea feasible. The clutches of the 1100's and all airheads not damped either. Therefore this theory should apply to them as well.

Blacque Jacque Shellacque said:

Interesting, but I do not find this torsional whip idea feasible. The clutches of the 1100's and all airheads not damped either. Therefore this theory should apply to them as well.

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Airheads especially later large displacement (R100) models had spline issues and spline lubrication was recommended, I think, at 10K miles intervals.

jammess said:

Airheads especially later large displacement (R100) models had spline issues and spline lubrication was recommended, I think, at 10K miles intervals.

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That's true. But airheads wear the splines evenly, not scalloped. My own R80RT has 360k KM and spline wear is negligible.

Blacque Jacque Shellacque said:

That's true. But airheads wear the splines evenly, not scalloped. My own R80RT has 360k KM and spline wear is negligible.

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Also, in the case of the airhead corrosion and fretting of the input splines occurs which is not an oilhead issue. Point I was making is that input shaft issues didn't begin with the oil head. Also, power output of an R80 with 32 mm Bings is much different than that of an R100 with 40 mm carbs. Another big difference in your R80 and my R100 is the final drive. Your R80 most likely has a 34-11 FD ratio and my R100 came with a 32-11 FD. Hence, less loading on trans input shaft splines on your R80. Another reason I changed my FD to 34-11 and it does make 5th gear much more user friendly. Another reason I like the R1100 over the 1150 is the 1100 doesn't have 6th gear which imo makes the 1100 more spline friendly.

Blacque Jacque Shellacque said:

That's true. But airheads wear the splines evenly, not scalloped. My own R80RT has 360k KM and spline wear is negligible.

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I don't know about scalloping, but my '75 airhead ate its spline @ ~25,000 miles many years ago. I know from trying to center things up last winter, that the engine and transmission axes are not aligned now, and the pilot diameters between the two won't let it align.

In hindsight, I probably could have pursued it a little more last winter when I went thru the bike. Instead, I just decided to keep lubing it more frequently.

I didn't learn anything from the "torsional whip" paper either. I think the guy is embroidering about the consequences of the second order torsional vibration inherent in any inline 4 cyl engine vs ways to counteract it.

roger 04 rt said:

The wear pattern on the shaft.........................wobble with wear.RB

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I think I understand what yuo meant here. You are suggesting that a warped flywheel or weird worn clutch disk would moment load the spline across the flex plate (spider).

I don't think this is so as the number of loaded cycles (transmitting torque while slipping only) is so small that we would not be seeing the kind of high-cycle fretting wear products we are encountering. The flex plate should be soft enough in generating overturning moment into the spline hub, that the wear component would be miniscule. I doubt the flywheel face etc would have that much run out.

The flex plate however is very stiff radially, and even a minor axes misalignment would generate a lot of spline wear dragging the clutch disc around. I figure the rotating radial force vector being applied to the spline in a misalignment is on the order of 1000 lbs. And it continues always being that full ~1,000 lb force vector every revolution whenever the engine is running and the clutch is released.

Remember many bikes don't show spline wear at all. Unfortunately, not enough though.

This is a very interesting thread.

I have never heard of these issues with a tranny input shaft wearing out when using a pilot bearing. Well, maybe in super high horsepower applications. Both Nissan and VW use the same sort of clutch design and I have rarely, has happened, seen input shaft splines wear out.

Bottom line, in my opinion, when you release the clutch, the clutch plate drops a bit, the pressure plate grabs it, off center and hence, the wear.

I am willing to go so far as to say that an urban bike will wear the input shaft much faster than a rural bike with fewer clutch inputs. I can say with absolute certainty, this problem is not unique to Oilhead Beemers but has been around a very long time.

Torsional vibration I believe contributes. Center line of the crankshaft to the center line of the tranny contributes.

I am a firm believer that gravity is the real culprit.

Keep posting though and don't accept my opinion. I am learning a lot from this thread.

Engine to tranny alignment

nrpetersen said:

I don't know about scalloping, but my '75 airhead ate its spline @ ~25,000 miles many years ago. I know from trying to center things up last winter, that the engine and transmission axes are not aligned now, and the pilot diameters between the two won't let it align.

In hindsight, I probably could have pursued it a little more last winter when I went thru the bike. Instead, I just decided to keep lubing it more frequently.

I didn't learn anything from the "torsional whip" paper either. I think the guy is embroidering about the consequences of the second order torsional vibration inherent in any inline 4 cyl engine vs ways to counteract it.

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Curious what you found to prove your airhead alignment was out of spec?

In my case - 1983 R100RT @ 179,000km on original input shaft by way of records (I've had since 110,00kms) and I have the transmission out at this point as I'm working with a paddle disc as an upgrade project.
I've dialed both the engine belhousing surfaces, as well the tranny face and protruding support lips and found:
-transmission shaft has potential to move 0.002" when loaded to side, but provides zero's when measurements are taken relaxed with shaft facing vertical.
-engine flywheel would move roughly 0.002" again (via main bearing) when coaxed with a pry bar, but provided immeasurable runout.
-I was suspicious of the "smallish" line up lips on the bottom two points of the transmission (the piloting is not continuous but provided by short sections of material coming from the tranny side into engine side recessions), but those appear quite normal and unworn.

Curious how line up is controled on the oilhead six speed, is it via dowels? Has anyone documented "misalignment" by taking measurements?

Lorne.

Blacque Jacque Shellacque said:

Interesting, but I do not find this torsional whip idea feasible. The clutches of the 1100's and all airheads not damped either. Therefore this theory should apply to them as well.

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Yes, but those have full spline engagement.

R100RTurbo said:

Curious what you found to prove your airhead alignment was out of spec?

In my case - 1983 R100RT @ 179,000km on original input shaft by way of records (I've had since 110,00kms) and I have the transmission out at this point as I'm working with a paddle disc as an upgrade project.
I've dialed both the engine belhousing surfaces, as well the tranny face and protruding support lips and found:
-transmission shaft has potential to move 0.002" when loaded to side, but provides zero's when measurements are taken relaxed with shaft facing vertical.
-engine flywheel would move roughly 0.002" again (via main bearing) when coaxed with a pry bar, but provided immeasurable runout.
-I was suspicious of the "smallish" line up lips on the bottom two points of the transmission (the piloting is not continuous but provided by short sections of material coming from the tranny side into engine side recessions), but those appear quite normal and unworn.

Curious how line up is controled on the oilhead six speed, is it via dowels? Has anyone documented "misalignment" by taking measurements?

Lorne.

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2 hollow dowels are used to align the tranny to the engine on the 6 speed.

AntonLargiader said:

View attachment 42630View attachment 42631View attachment 42632View attachment 42633

No, they are on their way to looking like this:

Now, trust me on this: the splines on the clutch disk remain straight as they wear. You can see that in the pictures, too.

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Again looking at the R1150 input shaft wear pattern, I think it is telling that all the wear is right where the clutch hub splines end. It is fascinating that the end of the hub (a softer material) can cause so much wear and at what looks like a 5 degree angle on the input splines.

I'm thinking that with full insertion, that end of the clutch hub is moved past the end of the splines, eliminating whatever the end-of-hub cutting effect is. It will be interesting to see GSAddicts when he eventually pulls the transmission.

Does anyone know why BMW went to the hydraulic clutch on the oil head? What advantage does the hydraulic clutch have over cable operated in this application? I certainly can't see how the hydraulic clutch benefits we the end users.

R100RTurbo said:

Curious what you found to prove your airhead alignment was out of spec? .

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It stripped out the spline suddenly about 1995 at about 25,000 miles. That was before this forum etc & I thought it might be because there was no obvious factory lube in the area. Just lotsa rust and grey stuff inside the clutch housing. I replaced everything (shaft and clutch disk) & reassembled using Neva Seize lube.

Recently I opened it up again to relube with that same anti seize. Things looked good (i. e. no real wear) but there probably were only an additional 5,000 miles on the bike (the odometer had quit). On reassembly, I left the bolts between the engine and transmission very slightly loose and started the engine. By bridging the interface with my finger, despite the pilot diameters I could feel a slight breathing whenever the clutch was let out. I tried releasing and re-engaging the clutch many times (maybe 20) but was never able to get that micro-motion detected by my bridging finger to go away, or even to change. Something was prying between the clutch/transmission rotation axis and the crankshaft axis. The alignment between the two is determined by a pilot diameter which is near the OD of the entire clutch housing - perhaps 10 inches in diameter. Not to be casually distorted.

I decided that reworking that large a pilot diameter was practically hopeless & that re-lubing was the best way out of this dilemma. In hindsight, maybe I should have tried to at least find out the geometric nature of the alignment error.

I now suspect that partial circumference shims might deform the pilot interface enough to eliminate the error. But how much? and where? The assembly is absolutely blind & I didn't feel like tearing the transmission apart again just to indicate on the input bearing bore like I had done with another R1100 bike here in town (see my post number 65 at http://forums.bmwmoa.org/showthread.php?56977-Clutch-and-input-shaft-spline-%C3%94%C3%87%C3%B4-need-advice-please/page5). I should have checked the crankshaft bearing clearances with a dial indicator, but didn't. I did try a quick multi-directional set of prys on the flywheel but didn't feel anything significant.

Hollow Dowel Alignment

GSAddict said:

2 hollow dowels are used to align the tranny to the engine on the 6 speed.

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Well, if a mis-alignment issue did exist on a six speed, I think all can agree that stress and wear to the beleaguered "mostly engaged" splines would benefit/ reduce from a correction.
How to do?
Perhaps a ring might be machined accurately with dowel pin center line established that could be located onto either engine or transmission (dowel protruding one side, with recess the other) to dial each side and denote correction required. Offset dowels might be tough to machine with such potentially small corrections, or oversized ream fitted on a corrected circle. Obviously a repair shop tool - perhaps this is in existence?
I concur with the opinion that gaining full spline engagement (especially when it runs out so close to disc center line on a rather flexible plate) would be beneficial, just another opinion however.