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jweicht's Avatar
 
Join Date: Jul 2004
Location: S. Central PA
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Happy 4th!

Mystery solved, mates. This was one of those neat and unique mechanical failures. I'll lead you through my morning... (took a bunch of pics along the way to show you, but can't get them downloaded to the computer at the moment for some reason. I'll add them later).

First of all, just for giggles I tried bleeding the clutch fluid line and as I suspected got no air but thick dark liquid goop which was gearbox oil mixed with the DOT 4 fluid. My wife came into the room (I've got a sweet bike work area in my laundry room) and asked "What's that smell?" - even she could smell the unique gearbox oil odor. I left the bleed port open and allowed it to drain into a pan for a while to get as much of the fluid/oil mix out of the system all the way from the master cylinder. On to the slave cylinder!

In spite of what the manual says, there is plenty of room to remove the clutch slave cylinder without unbolting the subframe for extra clearance. I removed the rear wheel, the left lower saddlebag mount, and the rear shock for unobstructed access to the slave cylinder. Removed the fluid line coming from the master cylinder, then removed the three bolts and pulled the cylinder straight back and tilted it up to clear the frame tube that crosses behind it (the thing the manual says it won't clear). Lots of brown gearbox oil goop in the gearbox bore where the cylinder mounts, but not enough that it ran overboard. The rear end of the clutch pushrod was of course in the center of the bore, and the end was dry and kinda rusty looking - at this point my old R1100RS memory bank kicked in and I said Hmmm. Pulled the cylinder out and turned it around to look at the business end. The inner race of the throw-out bearing where it contacts the clutch pushrod was cocked to one side and very loose to the touch. Bingo! My second Oilhead throw-out bearing failure! The bearing on my '94 R1100RS fragged itself at about 30k miles, just in time to ruin a 3 day trip. It's clutch followed shortly afterward, the friction material worn down all the way to the rivets - the new clutch assembly I installed was BMW's "improved" version. It still looked great when I traded the bike with 78k miles.

Back to the S story. The throw-out bearing is held into the slave cylinder with a snap ring. Removed the snap ring and out came the piston/throw-out bearing assembly and the spring behind it. I pounded the open end of the throw-out bearing/piston into my hand and four of the tiny ball bearings came out. I also noted that the inner bore of the slave cylinder was not very smooth as I would have expected it to be.

So, I had two separate issues here: Failure of the bearing and gearbox oil in the clutch fluid. Although the two may be totally unrelated, it could be that the throw-out bearing failed which then caused the bearing/piston assembly to get beat around in the cylinder bore which lead to piston seal failure which allowed gearbox oil into the fluid line. In hindsight, when the RS throw-out bearing failed it was exactly same symptom as what happened on the S - like I had a clutch cable break about 90% of the way through, still a tiny bit of disengagement when I pulled the lever. Well, I'm buying a new slave cylinder! The good news is, I had to pull the Paralever to replace the RS's bearing, this project is much easier.
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'07 R1200GS Adventure "Brutus"

Last edited by jweicht; 07-04-2006 at 08:51 AM..
Old 07-04-2006, 08:44 AM
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OK, the camera and computer decided to talk to each other again, so here are some pics to help illustrate the previous post about what I discovered:

Making room for surgery.


The gearbox bore where the slave cylinder fits. Notice the little metal fuzz on the pushrod - remnants of the failed throw-out bearing.


What came out of the bleed port into my Mityvac.


The "mud" in the clutch fluid reservoir.


The slave cylinder components. Note the cocked throw-out bearing inner race.


The four balls that came out of the failed bearing into my hand.



Hope this all makes sense.
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'07 R1200GS Adventure "Brutus"

Last edited by jweicht; 07-04-2006 at 10:04 AM..
Old 07-04-2006, 09:56 AM
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Nice! So is that the extent of the damage? Or do you think there could be more damage lurking within?
Old 07-04-2006, 12:13 PM
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Christ..........that looks NASTY!
Looks like itll need a supa good cleaning!
Do ya think anything has contaminated the clitch disk?

Thanks for the insight......
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Last edited by RoundelRider; 07-04-2006 at 01:17 PM..
Old 07-04-2006, 01:07 PM
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I'm very optimistic that this is the extent of the damage. When the RS's throw-out bearing failed it was much nastier than this, even messing up the end of the pushrod. There was no felt washer on that pushrod (BMW obviously didn't make that mod until later, this happened to me in '00), and there was no gearbox oil present at the forward end of the gearbox. I really don't think at this point that any clutch fluid made it up there yet either. I'm not pulling the tranny to find out, I know that!
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'07 R1200GS Adventure "Brutus"
Old 07-04-2006, 02:13 PM
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how many miles on that steed?
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Old 07-04-2006, 06:47 PM
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Nautical miles??? Thats nasty looking.
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Old 07-04-2006, 07:01 PM
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Just shy of 42k miles right now, all but 404 of them in the last 2 years. I don't think the fact that the bike pretty much sat for the first five years of its life is a factor though.

I know they are the same on most all BMWs with a single plate dry clutch, but that throw-out bearing just seems so fragile of a design to me. Especially now that I've had two of them fail, I am more determined than ever to not keep the bike in gear/clutch in while at a stop, just so those little balls aren't loaded any longer than they have to be. I can almost hear them screaming in pain!!!!!!

It'd be interesting to know how many other clutch slave cylinder failures actually revolved around a bad throw-out bearing. My two incidents seem to be very isolated from everything I've read on forums throughout the years, I suppose I'm just unlucky in that regard. I certainly don't sit in traffic much or otherwise subject the throw-out bearing to anything other than normal use. Anyone else have one or more of these puppies fail on their Beemer?
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'07 R1200GS Adventure "Brutus"

Last edited by jweicht; 07-05-2006 at 02:41 AM..
Old 07-05-2006, 02:22 AM
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After letting the bike sit for some time (about a month, family things you know) I took it for a ride. When I started it up I had the clutch lever pulled in as I always do and after starting the motor all I could hear was a screech from the trans. I shut the bike down and when I restarted the screech started then went away. Seems like that is the start of the throw-out bearing failure. Question now is do I do the work myself or have it done under warranty after I trailer it to the shop?
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Old 08-03-2006, 10:41 AM
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you paid for the extended warranty, correct? of course you have them do it- that's what you already paid the big $ for.
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Old 08-03-2006, 11:58 AM
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Sure was. Just talked to Browns service department. They ran my VIN and according to BMW I have no open items/recalls on the bike. Also, I was told I am still in the 3 years, 36,000 mile factory warranty timeframe.

I talked about this issue and asked if there was any recall or service bulliten as many are starting to have issues about the throw-out bearing / slave cylinder and she got quiet then told me there has been noting issued by BMW at this time.

I wonder is this is something they (BMW) are trying to ignore until it comes up on each specific bike.

OBTW Browns is booked until the end of the month so she advised me to call soon if I want them to do the work.
WayneO
Old 08-03-2006, 12:07 PM
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My clutch has been gettin' a bit soft lately. I was going to bleed the system first just to see if it'd change anything. The bike's got just about 30k and the fluid was changed out at 24k so it seemed odd that I'd suddenly need to bleed it. I decided to check here and found this thread. When I opened my reservoir, the fluid was dark, thick and smelled oh so yucky. Sure enough, gear oil in the ol' reservoir. I ordered the slave cylinder and gasket from Chicago BMW. The sales guy reminded me about the crush washers on the lines and I also got the bleeder tool for a grand total of about $120 plus shipping. The cylinder alone was quoted as $131 locally even though it lists for $121. Thanks Chicago BMW. Good price, friendly service. Can't wait for it to get here.
Old 09-09-2006, 05:02 PM
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j weicht, I think you answered your problem when you said you would never keep it in gear at a stoplight. I've had that drilled into my head by my father who was an old BMW mechanic. The throwout bearing is fragile and does not like the clutch lever engaged for extended periods of time.
Old 09-09-2006, 07:37 PM
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