Clutch and input shaft spline - need advice please

[PGlaves]

Very interesting. Thank you for your explanation and advice, nrpetersen.

I'll check the flywheel (as much as I can) and follow your advice during transmission-engine bolt up. However, I don't fully understand how the clutch would force the transmission offset considering that those dowel pins seem to keep the cases pretty snug. But you did question the stiffness of the housing.

I don't think the splines can be lubed through the starter opening; unless there is a technique that I am not aware of.

If the disk is slightly off-center when the transmission is installed it makes aligning the splines and the clutch rod entry into the pilot bearing in the crankshaft difficult. But I seriously doubt it would allow you to bend the transmission case or bellhousing. Those are stiff enough to constitute the main frame of the motorcycle. And, the clutch is going to be relieved of any lateral pressure on the clutch disk the very first time you pull the lever and release the spring pressure so any lateral pressure will not exist through any heat cycles. As an aside, as soon as there is appreciable wear on the splines gravity will slightly off center the clutch every time it is fully released in a stopped position. Then when you engage the clutch it engages in that slightly off centered position. I suspect it tends to recenter when you shift to 2nd, etc. But once worn a little the splines wear faster thereafter at an ever increasing rate.

[nrpetersen]

If the disk is slightly off-center when the transmission is installed it makes aligning the splines and the clutch rod entry into the pilot bearing in the crankshaft difficult. But I seriously doubt it would allow you to bend the transmission case or bellhousing. Those are stiff enough to constitute the main frame of the motorcycle. And, the clutch is going to be relieved of any lateral pressure on the clutch disk the very first time you pull the lever and release the spring pressure so any lateral pressure will not exist through any heat cycles.

My contention is that it never recenters. If there was an initial misalignment, that misalignment will reappear and the resulting shear force across the spline will be present every engine revolution. The spline shear force vector will be stationary, as the spline rotates. If I was to build a spline wear fatigue test system (my pre-retirement job) I would use a rotating spline set and radial misalignment control.

As an aside, as soon as there is appreciable wear on the splines gravity will slightly off center the clutch every time it is fully released in a stopped position. Then when you engage the clutch it engages in that slightly off centered position. I suspect it tends to recenter when you shift to 2nd, etc. But once worn a little the splines wear faster thereafter at an ever increasing rate.

Again - it never recenters except for the trivial case where the clutch is disengaged. The radial stiffness of the aluminum housing with its thin and open sections could be checked with a dial indicator & a screwdriver to pry things. I am suspicious of the R series in that they are the only ones that have the open starter port.

Later - OK, if the clutch disk - engine transmission assembly is elastically sprung/dragged together with the engine transmission bolts, and assuming the alignment dowels have no clearance and are in the correct position, and the crank main bearing, and the spline clearance is near zero, and there is no housing deflection, then the clutch, when first released, will allow everything to center. But heat cycles can't overcome the faying surface friction under typical bolt preloads.

There's a lot of chance for assembly errors to compound alignment problems despite an accurately machined clutch housing.

[nrpetersen]

A radical screwball idea -

Maybe leave the engine-transmission bolts a half turn loose, start the engine, and repeatedly engage the clutch in neutral until a happy point is reached by the assembly where there is no relative motion between the two cases. Then slowly torque everything up.

My concern though is that there is nothing in such a lash up except chance that will ever lock the transmission to the engine with no run out. A finger bridging the case joint would be able to feel any motion though.

[jconway607]

Over many years, I have had to replace the clutch disc, flywheels, pressure plates, etc., on a variety of cars, almost all foreign made. In all that time I have never seen an input shaft with worn splines. Nor a clutch disc with worn splines for that matter. Many of these vehicles had high mileage on them. No one I know who buys a used car with say, 50,000 miles on it, immediately sends it to the shop to have the transmission dropped and the clutch assembly re-lubed. Any car company either suggesting, or requiring that, would be quickly out of business.

Taking these bikes apart, essentially splitting them in the middle on the oildeads-on, is no walk in the park. And often, it seems, the input shaft is worn. Well, there's $1700 for a transmission rebuild. And the worst part is that all you're doing is just re-setting the clock till it goes again. I'm just really curious what it is about these relatively little engines, and even littler clutch assemblies, that makes them so fragile, and such a maintenance problem to own? Like the one guy says, should you expect to split the bike in half every year or so just to make sure your "splines" are not on the verge of failure? This has got to be a moneymaker for the BMW dealerships.

There is no way to know from outside that these things are failing, or have proper lube, etc. As someone looking for a new bike, it's depressing to realize that the first thing I will have to do after driving it home is to disassemble half the machine, with a deep sense of dread that inside that shiny transmission case I will find a worn or shot input shaft. Yes, I know that Japanese bikes have their own problems, but taking them apart to lube/replace transmission shafts on a fairly regular basis doesn't seem to be one of them. Jeeeze, I would think BMW could come up with a solution to this seemingly unending and major problem/headache on their bikes. Apparently I'd be wrong, though.

[PGlaves]

Over many years, I have had to replace the clutch disc, flywheels, pressure plates, etc., on a variety of cars, almost all foreign made. In all that time I have never seen an input shaft with worn splines. Nor a clutch disc with worn splines for that matter. Many of these vehicles had high mileage on them. No one I know who buys a used car with say, 50,000 miles on it, immediately sends it to the shop to have the transmission dropped and the clutch assembly re-lubed. Any car company either suggesting, or requiring that, would be quickly out of business.

Taking these bikes apart, essentially splitting them in the middle on the oildeads-on, is no walk in the park. And often, it seems, the input shaft is worn. Well, there's $1700 for a transmission rebuild. And the worst part is that all you're doing is just re-setting the clock till it goes again. I'm just really curious what it is about these relatively little engines, and even littler clutch assemblies, that makes them so fragile, and such a maintenance problem to own? Like the one guy says, should you expect to split the bike in half every year or so just to make sure your "splines" are not on the verge of failure? This has got to be a moneymaker for the BMW dealerships.

There is no way to know from outside that these things are failing, or have proper lube, etc. As someone looking for a new bike, it's depressing to realize that the first thing I will have to do after driving it home is to disassemble half the machine, with a deep sense of dread that inside that shiny transmission case I will find a worn or shot input shaft. Yes, I know that Japanese bikes have their own problems, but taking them apart to lube/replace transmission shafts on a fairly regular basis doesn't seem to be one of them. Jeeeze, I would think BMW could come up with a solution to this seemingly unending and major problem/headache on their bikes. Apparently I'd be wrong, though.

I agree, but then again, you can always buy a bike that needs to have the engine removed to replace the stator every so often. Pick your poison.

p.s. I have an R1100RS in the awkward tail up position, with the transmission sent off to Pennsylvania as I type, so I do feel the pain.

[jconway607]

p.s. I have an R1100RS in the awkward tail up position, with the transmission sent off to Pennsylvania as I type, so I do feel the pain.

Paul,
I, for one, would love to know just how many miles that R1100RS of yours that has suffered terminal spline failure has on it? Thanks,

John

[jammess]

I agree, but then again, you can always buy a bike that needs to have the engine removed to replace the stator every so often. Pick your poison.

p.s. I have an R1100RS in the awkward tail up position, with the transmission sent off to Pennsylvania as I type, so I do feel the pain.

Seems I read or heard somewhere that BMW is soon to do away with the dry clutch all together and go all wet clutch just like the made for Hondakawsusyammi.

[AntonLargiader]

My contention is that it never recenters.

Can you support that? When the clutch disk is positioned solely by the spinning input shaft, what is going to throw it off-center again when the clutch engages? And in that case, why wouldn't it be thrown off-center even if originally installed perfectly?

A radical screwball idea -

Maybe leave the engine-transmission bolts a half turn loose...

It must have been in a different thread where that came up recently. You're not familiar with the system in question: not only is there simply no movement between the engine and transmission due to the dowels, but the upper bolts are heavily obscured in later reassembly.

[Bohan]

...... Taking these bikes apart, essentially splitting them in the middle on the oildeads-on, is no walk in the park. And often, it seems, the input shaft is worn. Well, there's $1700 for a transmission rebuild. And the worst part is that all you're doing is just re-setting the clock till it goes again.

..... As someone looking for a new bike, it's depressing to realize that the first thing I will have to do after driving it home is to disassemble half the machine, with a deep sense of dread that inside that shiny transmission case I will find a worn or shot input shaft.

My thoughts exactly. Needless to say, right now I am quite disappointed with BMW, R bikes in particular. If I knew going in that I'd have to replace the transmission input shaft and clutch assembly at 54k miles I would have considered another model or manufacturer.

[PGlaves]

Paul,
I, for one, would love to know just how many miles that R1100RS of yours that has suffered terminal spline failure has on it? Thanks,

John

357,658 miles

[PAS]

Let me ask again. My recently purchased 2003 R1150RT now has 13K on it. Would the spline grease still be good to go to 40K? Or is that asking too much of old grease

[PGlaves]

Let me ask again. My recently purchased 2003 R1150RT now has 13K on it. Would the spline grease still be good to go to 40K? Or is that asking too much of old grease

If that were my bike and I intended to keep it, I would bite the bullet sooner rather than later. Pick a convenient time rather than a specific mileage. Then feel free to go 40K from that point.

[nrpetersen]

Can you support that? When the clutch disk is positioned solely by the spinning input shaft, what is going to throw it off-center again when the clutch engages? And in that case, why wouldn't it be thrown off-center even if originally installed perfectly?

As soon as the clutch quits slipping with respect to the flywheel, there will be maximum spline radial loading due to misalignment one half turn of the flywheel later. (Not sure I understand yr question?)

It must have been in a different thread where that came up recently. You're not familiar with the system in question: not only is there simply no movement between the engine and transmission due to the dowels, but the upper bolts are heavily obscured in later reassembly.

The only advantage of having a spinning engine when aligning the engine to the transmission is then the input shaft is aligned to the hydrodynamic running rotation center of the crank, rather than the sagged location of the crank as determined by static run out measurements and fiddling with the dowels. That was the initial reason I measured the rear main clearance as described above.

I recall a post a couple of years ago on a spline failure of a nearly new bike which had no dowels in it from the factory.

[bikerfish1100]

there was an extensive write up on the Pelican site (with pictures) of a clutch realignment done on a R1100S. it included filling existing holes, realigning the engine to bell housing interface using dial indicators, and then redrilling new holes that corrected the misalignment. i looked for the thread, but it is no longer available (poster had originally included links to his own pages, rather than copying the entire job to Pelican, and his linked pages are now down).
however, his process corrected the problem- but it was not about an error in the clutch assembly process, but rather a physical misalignment between the engine and the trans housing. minimal misalignment, but sufficient to create mucho spline failures until corrected.

[jconway607]

357,658 miles

Let's agree Paul, this is unheard of mileage for most people who can't spend 12 hours a day in the saddle. But if I go by that single number, I have to assume a few things.

One, everyone, like the original poster of this thread, who seem to have spline failures at much lower mileages (54K in his case) just got bad bikes from BMW. We both know this guy isn't the only one with this problem. So...quality control at BMW suffering? Production a bit too high?

Two, are you saying that your 357,658 mile bike was never apart before for the famous spline lube? If so, we are all chumps for believing we have to do it about every 40,000 miles or so, which if memory serves, you yourself recommend. That's roughly every three years, maybe. Of course immediately if the bike is just old and has sat. (the 13K, 2003 guy on this thread) Let's see , 357,658 miles divided by 40,000 means your bike has had to be split apart roughly NINE times to do this "routine" maintenance job. Dealerships charge about $1000 to do this? Nine thousand dollars in maintenance costs. Not bad. Of course if you are practically living on the bike, I suppose it's cheaper than a house payment.