R1100S Judder on Downshifting

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jonwills
Posts: 5
Joined: Fri Jan 25, 2008 1:04 pm
Location: Gosport, Hants

R1100S Judder on Downshifting

Post by jonwills »

I've got a 'Y' reg r1100s, 24,000miles fully serviced, replacement gearbox and final drive bearing 12,000 miles ago. New final drive oil seal 1,000miles ago as part of annual/6,000mile service.

It has recently started developing a judder through the transmission/final drive as the clutch is slipped in during downshifts. There is no judder when pulling away. If the revs are matched on down-shifts it all works fine.

I've had the back lifted off the ground and removed the brake caliper to check the bearing for play (all okay) and I'm not aware of any extra backlash play in the final drive.

Any ideas where the problem might be?
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oyster
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Location: retirementland kent

Post by oyster »

Tyre wear/tyre pressure? 36 f + 38 r.
Oyster. 1999 R1100S. Almost original.
jonwills
Posts: 5
Joined: Fri Jan 25, 2008 1:04 pm
Location: Gosport, Hants

Downshift Judder

Post by jonwills »

The rear tyre is a little square from commuting but the pressures are all fine (checked weekly), I'm sure this isn't the rear tyre skipping it also happens at very low speeds if the clutch is slipped in using the engine braking.

I was wondering whether there might be a problem with the clutch but that doesn't make complete sense when it is absolutely normal when pulling away, when it gets slipped the most.
jonwills
Posts: 5
Joined: Fri Jan 25, 2008 1:04 pm
Location: Gosport, Hants

Post by jonwills »

I've sorted the judder now.

It appears that the BMW shop managed to put the Shaft back together out of phase when they replaced the Final Drive oil seals just before Christmas. I had it apart to check the UJs as I thought that they may have been the problem but they were fine as was the Final Drive and Paralever bearings. When I put it all back together it felt great and has done since.
r550s
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Location: Baaarnsley

Post by r550s »

interesting point - wrong phasing causing judder on downshifts. It's been mentioned a few times that a 3-4000 rpm cyclic thrumming in third/fourth on a level road is due to wrong phasing (happened to me), but afaik the downshift thing is new, makes sense though. Bet you're chuffed you solved it!
'Hinterachsge' translates as 'rear axle'.(Not 'Differential', so f*** off)
jonwills
Posts: 5
Joined: Fri Jan 25, 2008 1:04 pm
Location: Gosport, Hants

Post by jonwills »

Too right!

I guess the phasing was just wrong enough to cause some sort of oscillation at just the wrong moment. I didn't think to look to see how far out it was when I removed the final drive as I wasn't looking for that at that point. Now it's right I realise that there was more vibration generally.
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