Clutch Spline lubrication through the starter hole...?

[biometrics]

I read this idea this morning over on the BMWMOA site... (here is the source URL to give the original author Ken F the credit: http://www.bmwmoa.org/forum/showthread.php?t=63028 ) but there was only one comment to the idea over there...

 

I thought the concept might get more discussion here...

 

...You can get to the clutch hub through the opening for the starter.

Why not put a small grease zerk in the hub of the clutch, and machine a small groove around the inner part of the clutch hub splines for the grease to travel through?

 

Just thinkin.....opinions welcome.

 

Ken

 

I like this idea and I think this idea has some real merit for preventive maintenance.

 

If there were a way to insert the appropriate moly grease into the clutch/driveshaft joint from the hole where the starter is installed, it could definitely contribute to reducing spline failures.

 

I had previously thought that instead of a grease zerk (which might influence the balance of the clutch unless you put several equidistant around the hub), just a series of holes drilled in the clutch hub at an angle which would permit the insertion of an appropriately sized syringe needle like the type used by veterinary services for internal irrigation (see attached photo) could be used to insert the moly grease... without a major disassembly of the bike.

 

I would love hear member comments on these 2 ideas, especially dirtrider, GeorgeinVA at BUA, and Anton... all others folks who do their own wrenching are especially welcome too.

 

Thanks, -John

[biometrics]

Here is an example of a grease zerk fitting for those that don't know what they look like...

[MT Wallet]

If you went to all the trouble to gain access to do this work wouldn't it be just as easy to grease the splines while things are open?

[Tobias]

After reading the link I have several concerns:

Would putting a zerk fitting on the clutch hub create a balance issue?

A grease zerk in the clutch hub would only lube the single spline.

You can't see where the grease is going and eventually excess grease will push out and contaminate the friction disc.

Drilling the clutch hub to accept a syringe seems equal to perforating a tear strip on paper.

[dirtrider]

Morning John

 

Adding a grease fitting to the clutch disk hub center would be so close to the shaft center line it should be a non issue balance wise.

 

As to using a series of holes in the hub --that could be a problem as those holes would end up full of grease so the fast spinning disk could throw any remaining grease all over the clutch area.

 

I have mixed feelings on cutting a groove in the disk splines then adding a grease fitting.

 

My first thought is we shouldn't have to ever grease the clutch splines if the alignment is correct. No call-out in the BMW service manual to grease the splines. The good I see coming from tearing the thing apart & greasing the splines is the INSPECTION part not the greasing part.

 

OK, my feeling on greasing the splines aside--

 

A few problems I see with cutting a groove in the disk splines then adding a grease fitting are:

 

Even with the internal groove cut in the disk spline, with just one grease fitting you are asking the grease to enter through the grease fitting, follow that groove around then evenly find it's way to grease all the other splines the same even amount. In reality most likely the grease will over grease the splines in the grease fitting area & not much will find it's way into the far side spline area with enough force to move out & fully lubricate the far side splines.

 

There is GREAT RISK of over-greasing the hub area as you can't easily control the amount of grease that flows through to the spline area.

 

Once you see grease appear on the edges of the splines it is over greased at that time & there is great risk of the spinning disk spinning that grease all over the clutch friction area.

 

Even if you could control the greasing process the first time, after many heating & cooling cycles & normal usage there is a good chance that groove would partially plug up with old hardened grease & crud so you are back to not knowing if a new shot of grease is lubricating the off side splines.

 

Lubricating spline hubs works pretty good in farm equipment but the parts are exposed & excess grease thrown all around doesn't get on any clutch friction surfaces.

 

The thing to keep in mind here is there are many BMW boxers that go full life on the original clutch splines without any extra lubrication & some BMW boxers that fail the splines like clock work even with a new trans shaft, new clutch disk, & good lubrication at each disk/shaft replacement interval of 20,000+ miles or so. What's the reason?-- Probably alignment.

 

[roger 04 rt]

... My first thought is we shouldn't have to ever grease the clutch splines if the alignment is correct. No call-out in the BMW service manual to grease the splines. The good I see coming from tearing the thing apart & greasing the splines is the INSPECTION part not the greasing part. ...

 

Ever since I was a kid, I've enjoyed taking things apart to see how they work and putting them back together. That said, I hadn't realized that well aligned splines could be run without lubrication.

 

My dad, a lifelong heavy equipment mechanic, has always been a fan of using only enough grease to put a film on surfaces. It's all that protects and lubricates, the rest just attracting dirt and getting thrown off.

 

Maybe I'll go the route of just inspecting the rotational movement through the starter opening.

 

Good food for thought, thanks.

[biometrics]

If you went to all the trouble to gain access to do this work wouldn't it be just as easy to grease the splines while things are open?

 

Hi Richard, I guess I failed to make myself clear that this modification would be made during a required clutch disk change, and not specifically to make lubrication possible...

 

Thanks to all for your comments... It helps clear the cobwebs when others share the problem.

[Uncle Beemer]

Morning John

 

SNIP

 

My first thought is we shouldn't have to ever grease the clutch splines if the alignment is correct. No call-out in the BMW service manual to grease the splines. The good I see coming from tearing the thing apart & greasing the splines is the INSPECTION part not the greasing part.

 

OK, my feeling on greasing the splines aside--

 

 

 

I am so glad to finally hear someone say this . Thanks Dirt Rider

[Stan Walker]

No call-out in the BMW service manual to grease the splines.

 

So sorry but NOT entirely true!

 

The R1150RT Service Manual calls for greasing the clutch plate and gearbox input shaft along with diaphgrgm spring contact surfaces when replacing the clutch. See page 21.7 under installing the clutch. I would also like to point out they come from the factory with greased splines.

 

Same for the R1100 Repair manual.

 

Stan

[dirtrider]

Afternoon Stan

 

What you are referring to is at initial assembly, or at clutch replacement time.

 

There is no BMW specified periodic lube (or re-lube) of the clutch spline area ether by mileage, time, or annual service, & no service bulletin from BMW that I have ever seen saying to do so.

 

Seeing as the original poster was talking about periodic spline re-lubrication the comment in the posting I made above was in the context of maintenance type spline lubrication not initial install or new disk replacement.

 

[smiller]

My first thought is we shouldn't have to ever grease the clutch splines if the alignment is correct.

Yes. It is a frequent assumption that lack of lubrication causes spline failures but I don't think that is really the root cause. If spline alignment is correct then the splines will live just fine getting greased only when the transmission is off for some other reason, such as a clutch replacement. Otherwise disassembly of the bike merely to do a spline lube may be more likely to do more harm than good. If alignment is incorrect then more lube might make things last a little longer, but the real problem is in the alignment and accelerated wear will occur regardless of the amount of lube present.

[ltljohn]

There is an old thread about lubricating the splines through the starter hole HERE . I have ther splinal tap tool that Jamie made. Drop me a PM with an address and I will send it to you.

[JamesW]

Evening D.R., I hear what you say about not needing to lube the input shaft splines because they will be fine if alignment is correct. That said I believe BMW did come out with a requirement for lubing the splines on the airhead bikes at, I think, 12K miles. Seems trans input shaft splines became an issue when displacement became close to 1000 cc.

 

I have lubed the splines on my 1150 at around 35K miles and found their condition to be pristine so if nothing else I felt better. When I bought my new '93 R1100 last February I removed the trans and lubed the splines since 20 years of doing nothing might have hardened the factory lubricant. Upon inspection I found only small trace amounts of lubricant so at least I can say I started out with well lubed input shaft splines. When lubricating airhead splines lots of folks like to leave the 4 mounting bolts loose between motor and trans then fire the bike up and let out the clutch to insure good alignment. Wonder if this procedure would be a bad idea on our oilheads? I don't do this on my '81 R100RT, maybe I should? When lubing splines I use a 50/50 mix of SIG3000 and Honda Moly. One should only apply lubricant to the shaft splines NOT the clutch disc splines or thou shalt be replacing the clutch.

 

Another thought. If you are going to inspect and or lube your input shaft splines take the time to do the job right and that means separate the trans from the motor, clean and inspect, then apply lubricant wether you think the trans shaft splines need it or not. Now if you have an alignment problem no amount of taking apart, cleaning, and lubricating is going to, in the end, be of much help. IMO

[millbert]

I removed my starter and lubed the spline with Dupont Krytox in a long syringe (Babcock - ??) years ago,the know-how came from this board. No problems,50,000 miles and 7-8 years. It was harder than it seemed but I took my time used little grease,so it wouldn't be thrown on the clutch,worked out good. Got the grease from McMaster-Carr.

 

http://www2.dupont.com/Lubricants/en_US/products/Products_Greases.html

 

[Galactic Greyhound]

.......The thing to keep in mind here is there are many BMW boxers that go full life on the original clutch splines without any extra lubrication & some BMW boxers that fail the splines like clock work even with a new trans shaft, new clutch disk, & good lubrication at each disk/shaft replacement interval of 20,000+ miles or so. What's the reason?-- Probably alignment.

 

Hi Dirtrider,

 

I might be off the wall with this theory but I would be interested to hear any comments from yourself or others.

 

Am I correct in thinking that the R1100 gearbox input shaft is floating at the clutch end i.e. there is no pilot bush in the flywheel or clutch assembly to support the end of the shaft?

 

If this is so, then assuming that the transmission casing is mis-aligned to the engine casing due to factory error, when the clutch is operated (not engaged with the transmission) the friction disc will automatically centre itself on the input shaft.

 

The spline wear problem might therefore occur with the clutch released (driving the transmission) and the engine rotating as this would mean that the centre of the clutch disc/input shaft would not be aligned with the centre of the flywheel. This would cause the clutch disc/input shaft to describe a small circular motion around the flywheel/crankshaft centre which would fret the clutch disc and input shaft splines so causing the wear. Lubrication of the splines would therefore only postpone for a short time the inevitable catastrophic failure of the splines.

 

[David R]

Greyhound guy you have it right. There is no pilot bearing. The transmission shaft is well supported by the transmission. Its just a nub sticking out.

 

Leaving bolts loose would not help, there are dowel pins to keep everything properly aligned or mis aligned.

 

I too thought of drilling small holes in the hub for future lubrication. No grease fitting, just small holes for a syringe type greaser. If this was to be done and sold over the internet, there would have to be a way to limit the amount of grease in each hole. Too much grease will trash the clutch as well.

 

I also thought about a longer hub for more contact area. The input shaft could use about one more half hub length with no other modifications.

 

I finally did the right thing with my R1100RT.

 

Today I pick up a 2012 R1200R. Red!

 

One of my thoughts is 130 lbs lighter than my R1100RT may be easier on the entire redesigned drive line.

 

Oh yeah and over head cams.

 

David

[dirtrider]

Morning Ced

 

Yes the front end of the BMW 1100/1150 trans input shaft is free floating as the input shaft is hollow & has the clutch release push rod running through the full length of it. No way to use a front pilot bearing (a lot of front wheel drive automobiles with manual transmissions use the same free floating input shaft)

 

With a misalignment between the trans input shaft & center of crankshaft the clutch disk tries to center up on the spinning clutch pressure plate & housing. But in reality I would imagine the thing actually centers up just a bit off center because of the side load placed on the disk by the offset trans input shaft.

 

Here's the issue---Once the disk locks up to the pressure plate & housing if the trans input shaft isn't completely centered on the crankshaft it turns the clutch-to-input shaft spline joint into a sliding contact joint.

 

In a perfectly aligned clutch spline joint the loads that the splines see are just about all compressive. (very little sliding or oscillation). But, with just a little misalignment (actually very little) the spline contact load then becomes a sliding or a moving contact (a lot like a gear to gear mesh) only the mesh is between the exact same teeth all the time.

 

Now if you add in a bit of angular misalignment to the straight misalignment the joint not only has a sliding contact but also some oscillating movement.

 

With all the movement possible in a misaligned clutch spline joint just adding a bit of grease works good (for about a week) but the grease (even moly based) just can't stay on those moving/sliding contact surfaces long enough to do much long term good.

 

 

Or, as an old friend of mine in our powertrain durability department once told me when I questioned him on reducing spline wear.

3 things are the key to reducing spline wear -- ALIGNMENT, ALIGNMENT, ALIGNMENT. Or if you can't keep it aligned keep it continually lubricated & if you cant keep it aligned or continually lubricated (like in an oil bath) then change the joint material or make the joint large enough that wear isn't an issue.

 

Added: In re-reading your post above I see you mention fretting wear? In the worn spline BMW's I have worked on I haven't seen much signs of fretting as fretting wear is usually rough & pitted looking, the wear between the disk & input shaft I have seen is very smooth not rough.

 

[biometrics]

Thanks to all for your comments and ideas, and especially ltljohn for his kind offer to give me the tool...but based on this discussion I think I will just wait until I have time to do the proper disassembly and inspection as recommended by dirtrider...

 

Of course once I have done that, I may re-evaluate how I would lube it in the future ...

 

Thanks again,

-John

 

 

[dirtrider]

Morning John

 

I don't have any data to back this up but a personal view I have on lubricating BMW clutch splines or taking them apart for inspection is:

 

If you take one apart for inspection or re-lubrication & find there is wear evident that means the clutch disk & the input spline shaft has a very distinct wear pattern on each tooth of the spline. That also means that IF you don't get the clutch disk back on the input shaft EXACTLY in the same place you now have increased the risk of accelerated wear as the contact surfaces between the disk & input shaft now have drastically mismatching contact surfaces.

 

Like I said I have no data or any field testing on this in the BMW context so it is basically based on spline wear findings in other applications.

 

 

[roger 04 rt]

This thread has made me reconsider the whole idea of transmission spline lubrication. My plan for now is to evaluate the clutch plate rotational play through the starter opening, and to do nothing until/unless the play is unacceptable.

 

I do plan to replace the clutch slave cylinder due to its age.

[Jovial Henry]

My splines were worn so bad I replaced the trans with one out of a wreck. It had 57k and looked like new. Put in a new disk. Lubed very sparingly with anti seize. I was concerned about alignment but new trans went in although pretty tight on the alignment dowels. Only time will tell. First one lasted 50k.

[Galactic Greyhound]

Evening Dirtrider and David R,

 

Thank you both for your replies.

[nrp]

In order to get to the holy grail of infinite spline life at typical engine speeds, the radial alignment would probably have to be within say .001 inch. Ain't no way - especially when the main bearing clearance of the crankshaft is about .002 inch.

 

What's happening is that if nothing else, part of the piston forces are reacted across the spline to the transmission input bearing.

 

IOW - the crank will always be slightly fretting with the best of any spline alignments. Fretting doesn't necessarily have to have metal transfer, it manifests itself as simple rust powder.

 

I do think there is a future in hypodermic lubing with a slightly thinned moly grease - least for some of the lube intervals. There is clearance between the shaft tooth tip OD and the root of the clutch disk hub's teeth of about .030 inch. That's enough for a bent hypodermic needle which can be gotten cheaply from a druggie - or a drug store. Care would have to be used though to be sure to "grease" each tooth since a spine will not allow lubrication to otherwise migrate.