BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

Stopped by a local machine shop to see about having the offset dowels made (no problem) and I gave him my old input shaft for reverse engineering and quotation purposes. I'm going to have it made 0.2 inches longer than the original. If he comes back with a reasonable price, I will probably order a safe number - say 10. Enough to get the price within reason, but not so many that I couldn't safely sell them. I know that this forum won't reach the RT and GS crowd, but it's a good start. The shaft could go along with a loaner measurement setup and whatever size dowels are required as a package.
Not sure what the price will be yet. We still have to determine the proper material and hardening method. Hopefully well under the $900 price tag mentioned earlier.
I welcome any feedback on this. Positive, negative, interested in one, whatever.
Thanks

AndyRR

I may be wrong but I think people will hold off in response until they have an indication of the cost. My 10 cents.

Interesting/interested. Just wondering how the splined extension would be installed. Just thinking out loud (writing out loud??), you could probably get a better tolerance and tightness of fit to the clutch splines compared to the factory, and maybe get some better hardness - and get more strength than just the .2 extension...there's some possibilities here. Let's explore.

Count me in for one. What's current price for the OE replacement part?

Two R1150Rs in the garage means twice the chance of getting splined & shafted.

Will the additional 0.2 inch splined length fully engage the clutch hub throughout its range of motion?

How much longer is the privately made longer shaft currently available for $900 ?
I'd go with longer than .2 inch so it protrudes past the end of the clutch disc hub. As far as it can go without touching the crankshaft! The production costs for a precision machined hollow shaft, the premium steel needed and the surface hardening required are not cheap when the production run is very small.

To clarify, it's not an "extension" of the stock part, it's a completely new part.

I'm looking at the best solution to this problem in the form of a 2010 F800-ST where a clutch, final drive or even the engine are a piece of cake to completely disassemble. I'm sure it will have it's own German engineered shortcomings, hopefully only in it's history.

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If I recall, the previous after market input shaft maker didn't get enough orders at $900 to justify production beyond the prototype. It had closer tolerances and harder steel than the OEM input shaft in addition to being exactly long enough to completely engage the clutch splines. I'd be reluctant to commit to buying 10 of them and hoping to sell nine. One of my former partners loved to say: " hope is not a business strategy ".

AndyRR

Kudos for taking the initiative.......

Along the same lines the weakest part of the system is the hub of the clutch disc which is made out of sintered meatal (can you spell "cheap") and to not distract you from you venue, but the same can be realized by improving the metallurgy plus the .200" extension of the part (which will run it up closer to the bearing that supports the tranny input shaft). One would have to drill the clutch disc rivets and install the new hub.

I think that one of our ilustrious postershad taken it upon himself to pursue this solution with a clutch disc manufacturer....I never heard anyhing more.

Best of luck.........

Thanks for your replies. I really value your feedback.

Current price for the OEM part is $250.

0.2" would be what it takes to fill the clutch hub. There isn't a lot of room behind it before it would hit the diaphragm spring. I'll take some more measurements and see what we have to play with. Not sure exactly how long the $950 (I thought it was only 900) shaft was, but I don't believe it was ever produced beyond the prototype.

You are absolutely correct in that extending the clutch hub would also yield improvement. Bonus is that it is in the other direction (towards the trans case) so that both could be implemented so that the FULL length of the splined area of the input shaft could be used. A friend mentioned that there used to be (and perhaps still is) a local shop that would replace the friction material on clutches (because the splined section lasted forever ) and they were able to install some sort of flexible, spring-loaded rivets. These were able to take up a little slop and smoothed things out on takeoff somewhat. Have a longer hub installed with that type rivet and you might even be able to get away without the offset dowels. Problem is that now we are talking about another part being made, plus $150 for a new OEM clutch, plus assembly cost. This might be feasible if the price for the shaft is low enough. Someone undergoing this repair would be buying that clutch anyway.

The problem with producing this part is that there is a very limited number of people that KNOW they have a problem. This is why trying to collect deposits before placing an order didn't work. Someone placing a deposit early would likely wait months (with their bike in pieces, taking up garage space, spouse bitching about the mess, oh and NOT RIDING) before enough deposits were collected to make a minimum order.

AndyRR

Things have changed so much.....I used to have, when I was way thinner than at present, a Lotus Europa with a Renault engine, talk about cornering like a go-kart. I had a local clutch shop rebuild the clutch disc, change the springs and friction materials for less than $25....where is all of that now???

But I digress....my reference to the clutch disc is that it is the weaker of the two parts, the input shaft being the other. That being said to me it would be better to improve the clutch disc splined hub and use with the OEM shaft. If we enlarge the hub back it rides close to the input shaft bearing and places more of the cantilever load closer to the bearing.....but like I said before I'm not here to discount your efforts but to praise your initiative....

My first reaction is "respectfully disagree" - replacement of the input shaft with improved part is preferred over clutch hub changes. But the idea of alternative hub came up before, and if a new hub could be inexpensively produced (broaching the female splines for accuracy, assuming that the broach is off-the-shelf) and retrofit to the clutch, then this might be lowest cost option.

If/when splines fail in either of our bikes, I intend to balance the new clutch as part of the rebuild. I have heard distinct clutch rattle a couple of times when clutch was released on our Roadster, making me think it's the bike that will need repairs first.

Believing that a company's economic condition often reflects itself in its product quality, I note that Sachs was split up in 2001, with drivetrain components manufacturing purchased by ZF. Sachs is source for the OE clutch parts on R1150 bikes. <edit> I also see that prior to the ZF purchase, Sachs had been held by Mannesman AG... this is eerily analogous to AMF's ownership of H-D: both Mannesman and AMF initially involved in metals; Sachs and AMF involved in bicycle parts mfg.; , both parent companies diversified broadly and then sold off to stem losses.

Nonetheless, I intend to install an improved input shaft if available & reasonable.

Mark
Oregon
2002 Roadster
2004 Rockster

I'm of the camp that likes to make the easy shots first. Having a deeper/longer steel clutch hub replacing the BMW clutch's sintered metal part is the best approach. It eliminates the weakest link and does it cheaper because the transmission doesn't have to be taken apart -and- the hub will most likely be less expensive to make, special rivets and all.

It also has the ability to arrest the progression of minor/noticeable wear on less than new bikes like mine. It would be an excellent retrofit for BMW to make this expensive failure go away for good. From the looks of the clutch hub's partial shaft engagement, I suspect it's not representative of their reputed world class German engineering.

CycleRob wrote:It also has the ability to arrest the progression of minor/noticeable wear on less than new bikes like mine.

My thinking was that the input shaft would be a replace as needed item and the improved shaft simply offering a better alternative to the same, faulty OEM shaft when replacement was required anyway. There's no way I would expect anyone to replace an otherwise OK input shaft as a preventative measure. If I'm reading you right, you are suggesting that replacing the clutch hub might be a good idea for higher mileage bikes without any obvious misalignment issues other than the universal lack of full engagement. I think you and boxermania have made an excellent point. I'll poke around locally and see if there are any shop still doing clutch work like that. If a shop could install a relatively inexpensive, improved clutch hub, AND replace the pad material on an old clutch for near the price of an OEM clutch then perhaps we have something here.
I have the offset dowels, but I'm still waiting for pricing on the input shaft. I'm not sure I can resist the temptation to put her back together this weekend.
Thanks again for your feedback.

AndyRR

I'm really impressed with your work, in view of that I would like to add the following:

There doesn't seem to be any issues with the clutch facing material, in regards to wear. That brings us to the clutch disc hub. If you notice it has an extension towards the engine....if one can visualize drilling out the rivets and rotating the hub to where the extension now faces the tranny, now, by doing so the full spline contact of the hub to the input shaft has been realized re-capturing that portion lost due to the ~.200" hub to spline loss of contact in the original position. The only other issue would be to manufacture the hub from improved materials.

During my research of the failures and the potential sources I had obtained a donated clutch disc and input shaft which I passed on to another member that was collaborating on the project and was like you investigating an alternative solution.

I would be willing to assist you with exploring a hub solution especially on the design/manufacturing as I have some resources at my disposal, you would have to be the guinea pig as I no longer have my bike.

boxermania wrote:AndyRR

I'm really impressed with your work, in view of that I would like to add the following:

There doesn't seem to be any issues with the clutch facing material, in regards to wear. That brings us to the clutch disc hub. If you notice it has an extension towards the engine....if one can visualize drilling out the rivets and rotating the hub to where the extension now faces the tranny, now, by doing so the full spline contact of the hub to the input shaft has been realized re-capturing that portion lost due to the ~.200" hub to spline loss of contact in the original position. The only other issue would be to manufacture the hub from improved materials.

During my research of the failures and the potential sources I had obtained a donated clutch disc and input shaft which I passed on to another member that was collaborating on the project and was like you investigating an alternative solution.

I would be willing to assist you with exploring a hub solution especially on the design/manufacturing as I have some resources at my disposal, you would have to be the guinea pig as I no longer have my bike.

I have an oil soaked clutch I am willing to donate. I can EMS it to the US.

Anyone willing to donate $1000 towards my repair bill, you are most welcome. LOL

Extending the hub has already been done. Take a look at this link. The thread is on BMWSportTouring.com

http://bmwsporttouring.com/ubbthreads/u ... Post402610

The first post has a link to the pictures at http://picasaweb.google.com/johnlupton6 ... CLUTCHHUB#

Hope this helps.

oiasghar wrote:Hope this helps.

It helps a lot. Thanks! I liked this guys alternate approach. Re-boring the dowel holes in the transmission case is probably a little better than the offset dowels, but it would be more expensive and it needs to be right the first time. No do-overs. I was a little surprised that with what he apparently has at his disposal, he didn't re-rivet the hub to the clutch. I like the bolting solution mostly because - I CAN DO THAT! I wonder if he had to do anything special to ensure the hub was centered correctly.

boxermania wrote:AndyRR

I'm really impressed with your work, in view of that I would like to add the following:

There doesn't seem to be any issues with the clutch facing material, in regards to wear. That brings us to the clutch disc hub. If you notice it has an extension towards the engine....if one can visualize drilling out the rivets and rotating the hub to where the extension now faces the tranny, now, by doing so the full spline contact of the hub to the input shaft has been realized re-capturing that portion lost due to the ~.200" hub to spline loss of contact in the original position. The only other issue would be to manufacture the hub from improved materials.

Thank you, but don't get too impressed until I get the bike back together and put a few thousand miles on it. I'm just a blind squirrel tripping over nuts here.
I'm not quite picturing the rotate the hub part. I know you know what they look like, but so that we are all on the same page - here's the engine side:



And the tranny side:



In the stock setup, the input shaft stops approximately at the center line of the clutch. My original input shaft is at the machine shop, so I don't have a handy measurement of how much of the input shaft is unused. Extending the tranny side of the hub would possibly net more gain in interfaced area for less money, but I still see a need for the longer input shaft. I'm just a below average shadetree mechanic, not an engineer, but when I look at the setup I don't really like having all the engaged area off on the tranny side of the clutch. I would like to see the input shaft protrude past the center line of the clutch over to the engine side and use the little bit of engagement that is there in the stock setup. I may have wandered off the reservation here, so let me know what you think.

The total solution I'm picturing for a bike that's going to need the input shaft replaced is:
Viagra treatment to the clutch hub and input shaft.
Accurately measuring and correcting the offset.

boxermania wrote:I would be willing to assist you with exploring a hub solution especially on the design/manufacturing as I have some resources at my disposal, you would have to be the guinea pig as I no longer have my bike.

I would really appreciate your help. Do you think the shop that fixed your Lotus is still in business? Even though there may be no wear issues, I would still be interested in new clutch material and spring rivets if the price is right. If you would like to talk live, PM me your phone number and a good time to call.

snowprick wrote:I have an oil soaked clutch I am willing to donate. I can EMS it to the US.

Thank you. Please hold on to it for now. I have one new and one bad so I couldn't justify the shipping cost at this time. I'll PM you if we need it.

One step forward, one step back on the clutch hub. Found a clutch shop that can replace the center hub and clutch material for a reasonable cost. They said that spring dampening is not an option on a clutch of this size. They suggested that I try to find an existing application that has the same hub profile with the greater depth I'm after. Cannibalizing a $40 automotive clutch for the hub I need sounded like a win-win, so I trotted merrily down that path to find an apparent dead end. There are a few automotive applications with a very similar hub profile, but nothing I could find would give me the depth. I called Sach's tech support and found that the hub profile was not 3/4" as I thought. It is 19.9mm or .783". Tech support was not aware of any other application that uses that profile (figures). So, it's back to the custom machining option.

Andy-

Sounds like the revised tramission input shaft is the best option for now. Why is it not surprising that the hub spline profile is a rarity?

Ever heard of these guys?
http://www.atiracing.com/products/bands/inputs.htm
Wonder if the torsion bar concept would help spline durability.

sweatmark wrote:Andy-

Sounds like the revised tramission input shaft is the best option for now. Why is it not surprising that the hub spline profile is a rarity?

Ever heard of these guys?
http://www.atiracing.com/products/bands/inputs.htm
Wonder if the torsion bar concept would help spline durability.

Thanks!! They looked good, but I gave them a call and they weren't interested in making anything custom. They are "too busy".