Author Topic: Clutch Issues on Cold Start  (Read 433 times)

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Online rcb78

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Clutch Issues on Cold Start
on: October 18, 2020, 01:10:31 AM
We veered off onto this topic on another thread so I thought I'd start a dedicated thread here.  This issue has been reported for both the 900XR and the 900R, which makes sense because they're the same platform.  This issue is that on the majority of cold starts the clutch acts like an on/off switch for the first few attempts to roll out, then starts working normally and continues to be good until the bike is shut off and fully cooled again.  For me this meant morning and afternoon commute so ambient temps don't seem to matter, it would happen in the 90s just as much as the 50s.
Anyways, BMW is aware of the problem and there is a PUMA case (don't remember what that stands for) in the dealers computers if they look it up.  The fix is a new clutch, mine was done yesterday, and from the look of the work order, it's the complete package and all related parts.  From speaking with others that have had the replacement, I expect this will completely resolve the issue.  What I did notice immediately on the ride home from the shop is that the slipper feature (anti-hop) of the clutch is working significantly better now.  So much so that I question if the original clutch was working as intended at all.  With the original clutch, I could easily lock the back end up by dropping gears aggressively.  I could hear and feel the engine brake control (MSR) working to minimize the lockup, but the clutch itself didn't feel much different from a normal clutch in any of my other bikes that don't have slippers.  This makes sense because slippers are just the other side of the coin when talking about 'clutch assist' features.  The assist feature drives the plates together mechanically in addition to spring force and the slipper feature drives them aparts, essentially negating some spring force.  I think the assist feature was faulty and slamming the plates together when cold and this fault extended to the slipper feature limiting how well it worked, if at all.
Another thing I noticed is that the friction zone seems to be just a hair larger than before, maybe another 5mm of travel (at far end of the lever) through the friction zone.
FWIW, the replacement clutch part number is from the 850GS.  It took a week to get the parts and a day to do the job (when scheduled) so if anyone else is having the same issue, get to your dealer.  You might be pleasantly surprised with an improved clutch when you get it back.