Do not downshift..... do not

deilenberger said:

Yes it is fine - and I was sort of curious on a motorcycle transmission how you can shift it without ever downshifting.. is there some magic here I'm missing.. my motorcycle transmissions are sequential - 1-N-2-3-4-5-6, 6-5-4-3-2-N-1 Somehow I can't figure out how to get from 6th to 1st without downshifting (color me slow today.. )

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There was a BMW that had a neutral lever. Whatever gear to neutral. I forget which one.

cjack said:

There was a BMW that had a neutral lever. Whatever gear to neutral. I forget which one.

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Hmmm, dunno about that, but the R12 (not R1200) and R17 had a "4 on the floor" H pattern shifter. Neutral always available.

The earlier bikes had 3 speed linear shift transmissions. 1st and 3rd were constant mesh, but 2nd was what I've heard called a "crashbox" gear, where you actually push the gears into mesh. 2nd gear had dogs on both faces, and the shift lever actually pushed it into mesh with 1st or 3rd, as well. Besides the normal neutral between 1st and 2nd, if you shift carefully, there's a neutral between 2nd and 3rd.

I just filed a complaint with the NHTSA. To get it on record.

Thanks for the suggestion.

Here is an interesting writeup on BMW transmissions. Interesting about using 90 weight only. No multigrade except in winter. I like the bit about o-rings to quiet the clunk.

http://groups.google.com/group/rec....ff84629a83/6acd8001a55ccb96#6acd8001a55ccb96#

PGlaves said:

A ball bearing is designed to take a given radial load - and in the case of a transmission the radial load is not huge, esentially created by the gear mesh in the transmission. I said "excess" radial load.

I did not make my original comments up. I learned them from a good engineering book on driveline mechanics. Most row crop and hay farmers know fairly well what happens when driveline slop happens in splined connections.

I suspect we will just need to agree to disagree on this one. I believe it - you don't.

You also might or might not believe my understanding as to why a damaged driveshaft universal joint caused an output shaft bearing to fail too - but the lab that did the analysis said it was excessive radial force causing a lack of lubrication because the clearances closed up. And this on a bearing designed to take a given amount of radial load.

We'll just have to disagree I guess.

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I get what you are saying there Paul. How is the BMW different from a car clutch with the shaft in a pilot bushing in the motor? Wouldn't the same thing happen in a car, and if so, wouldn't it happen in ANY dry clutch?

Not trying to be argumentative, just understand how the BMW motorcycle is different?

Jim

JimVonBaden1 said:

I get what you are saying there Paul. How is the BMW different from a car clutch with the shaft in a pilot bushing in the motor? Wouldn't the same thing happen in a car, and if so, wouldn't it happen in ANY dry clutch?

Not trying to be argumentative, just understand how the BMW motorcycle is different?

Jim

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Yes - in principle a badly worn spline in any dry clutch can off-center and impose loads on the transmission shaft bearing.

Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.

PGlaves said:

Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.

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This is something I have often wondered about. I have owned a lot of manual transmission cars (from Honda to BMW to Porsche), and I NEVER remember seeing a requirement/need to lubricate transmission input shaft splines in between clutch replacements.

"Why is that, Captain Ron?"

PGlaves said:

Yes - in principle a badly worn spline in any dry clutch can off-center and impose loads on the transmission shaft bearing.

Two differences that I know of: normally the transmission bearings are beefier (technical term for designed to take larger radial loads) and most can splines don't seem to have the habit of wearing like BMW motorcycle clutch splines do.

I have no positive knowledge why that is - but the length of the spline is usually much longer - thus spreading the loading over a larger area.

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Is THAT what beefy means?

Seriously, I often wondered why BMW didn't extend the length and add a pilot bushing. Any reason you can think of?

Jim

JimVonBaden1 said:

I often wondered why BMW didn't extend the length and add a pilot bushing. Any reason you can think of?

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Crappy engineering with the cost accountants controlling all the decisions. Same idea behind the "SEALED! Lifetime lubricated" differential fiasco. They saved the price of a pair of bolts for fill and drain (and machining operations to make the holes) and created a generation of BMW-Flamb?®.

BeemerMike said:

This is something I have often wondered about. I have owned a lot of manual transmission cars (from Honda to BMW to Porsche), and I NEVER remember seeing a requirement/need to lubricate transmission input shaft splines in between clutch replacements.

"Why is that, Captain Ron?"

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I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?

torags said:

I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?

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The snide answer is, "by doing it properly." To be more specific, the front edge of the clutch hub is in line with the disk and lube can be flung from this location onto the friction surface. But the rear of the clutch hub extends back and is not in line with the friction surface, so lube flung from this location will not foul the disk.

So to lubricate that spline you should first clean all traces of old lubricant, dust, and metal grindings off both the clutch hub splines and the input shaft splines. You should then apply a thin layer of lubricant so it completely covers the entire splined area of the INPUT SHAFT ONLY.

If you do this any excess will be pushed back along the shaft by the rear of the hub and if flung is not in line with the disk. If you put lube on the splines in the hub any excess will be pushed forward out of the hub, and if flung it will contaminate the friction surface.

If, after lubing the splines you (for whatever reason) slide it together and then again pull the transmission back, then you need to clean the lube that stuck in the hub out before you put the transmission back forward.

If you use this procedure and avoid slathering a lot of excess lube on or in the splines, disk contamination will not be a problem.

torags said:

I'm with you. How do you lubricate an input shaft without having the lube spritz on within the clutch cavity onto the clutch?

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I believe the short answer (to supplement Paul's long answer) is "you separate the transmission from the engine the same as you would if you were replacing the clutch".

Does that mean lubricating the shaft along the clutch plate travel? It is a dry clutch. The oil bathes are in the motor and the transmission and the cavity where the clutch is, is lube free - hence the term dry clutch. Or is the end of the thrust shaft lubed into the engine bearing.

Enlighten me if I'm off base.

Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

I don't know of any owner/maintenance lubrication means.

Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)

torags said:

Does that mean lubricating the shaft along the clutch plate travel? It is a dry clutch. The oil bathes are in the motor and the transmission and the cavity where the clutch is, is lube free - hence the term dry clutch. Or is the end of the thrust shaft lubed into the engine bearing.

Enlighten me if I'm off base.

Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

I don't know of any owner/maintenance lubrication means.

Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)

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For dry clutches, some lubrication on the input shaft helps the clutch plate slide back and forth more easily.

Lubricant is typically a paste of some kind. I prefer Honda's Moly60. It's very thick and sticks well. Making sure the input spline is well lubed allows the clutch to move easily, but also provides some lubrication and prevents the clutch splines from chewing on the input spline when power is fed through it.

I hope that's helpful. After you've lubed the input, you'll notice remarkably smooth and easy clutch and shift effort.

torags said:

Does that mean lubricating the shaft along the clutch plate travel?

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I believe the answer is "yes". Paul?

torags said:

Additionally that would have to be done on manufacture or any subsequent transmission removal, is that right?

I don't know of any owner/maintenance lubrication means.

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See notes below.

torags said:

Perhaps there are three reasons for the clutch spline to get cheesed. A sloppy engine bearing fit or a misaligned transmission. If yes, than responsibility for the condition lies with the last entity that assembled engine/trans, or extreme mileage (over 100K, but the plates would probably fail first)

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I believe you have correctly summarized the frustration many of us have with the (unspecified, but apparently necessary) periodic maintenance on a difficult-to-access part at intervals less than required for major repair (i.e., clutch replacement). We acknowledge and deal with it, even if we don't agree with or understand it.

KBasa said:

For dry clutches, some lubrication on the input shaft helps the clutch plate slide back and forth more easily.

Lubricant is typically a paste of some kind. I prefer Honda's Moly60. It's very thick and sticks well. Making sure the input spline is well lubed allows the clutch to move easily, but also provides some lubrication and prevents the clutch splines from chewing on the input spline when power is fed through it.

I hope that's helpful. After you've lubed the input, you'll notice remarkably smooth and easy clutch and shift effort.

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Sounds reasonable, But..... Even if you apply the lube with a qtip. The operation of the clutch sliding along the shaft will create a "oil burr" with the threat of centrifugal force throwing the burr onto the clutch plate.

I've never done a BMW clutch job and I don't know what the clutch spline is made of. However, If I did the metallurgical design I would use bronze for the clutch spline. Softer than steel and wear powder would dry lube the shaft. I just wouldn't use grease in that cavity, just my .02.

torags said:

Sounds reasonable, But..... Even if you apply the lube with a qtip. The operation of the clutch sliding along the shaft will create a "oil burr" with the threat of centrifugal force throwing the burr onto the clutch plate.

I've never done a BMW clutch job and I don't know what the clutch spline is made of. However, If I did the metallurgical design I would use bronze for the clutch spline. Softer than steel and wear powder would dry lube the shaft. I just wouldn't use grease in that cavity, just my .02.

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I think the trans input shaft spline is steel, and the mating clutch splines, since about 12/97 are steel plated with I think zinc. I think also that BMW uses some kind of white grease sparingly on new bike input splines.
A thin smear of moly60 or similar does not spin out on the clutch in my experience.

torags said:

Sounds reasonable, But..... Even if you apply the lube with a qtip. The operation of the clutch sliding along the shaft will create a "oil burr" with the threat of centrifugal force throwing the burr onto the clutch plate.

I've never done a BMW clutch job and I don't know what the clutch spline is made of. However, If I did the metallurgical design I would use bronze for the clutch spline. Softer than steel and wear powder would dry lube the shaft. I just wouldn't use grease in that cavity, just my .02.

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That's the difference between theory and practice.. in practice, contamination of the driven disk with lubricant hasn't been a problem. You normally use a brush to apply the Honda-60, it is very messy stuff.

And the clutch disk only moves a very tiny distance as the clamping force of the clutch pressure plate is released.. if I had to guess - less than 1-2mm.

I suspect bronze might not be a good selection for a power transfer spline - it's soft enough to deform with load. Once it deforms - it's done for. It does work well for bushings - but not bushings with any side load on them.

Paul, Jim, Dave, Don, et al,
How about spline lube on the Hexheads? Are people seeing the same need to tear half the bike apart to lube the splines on those models, or has BMW made some improvements that make them more "maintenance friendly?"

Paul - would you still recommend a 50K teardown on a Hexhead to check/lube the splines?

Thanks,

Motorcyclist said:

Paul, Jim, Dave, Don, et al,
How about spline lube on the Hexheads? Are people seeing the same need to tear half the bike apart to lube the splines on those models, or has BMW made some improvements that make them more "maintenance friendly?"

Paul - would you still recommend a 50K teardown on a Hexhead to check/lube the splines?

Thanks,

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Speaking for myself - don't think anyone knows yet. BMW did try to address a lot of "problem" areas in the R1200 design (some more successfully than others - like the rear-drive.) My hope is they addressed the need to lubricate the splines. Not too many people have over 50k miles on their R1200/hexheads yet - but a few do, and I haven't heard of any spline problems or shifting problems that might be due to dry splines.

I'm keeping my fingers crossed (which makes it harder to use the BMW switch-gear, but we won't go there.. )