The drive shaft was removed to be greased up anyway, and they examined the final drive, drive shaft splines etc at the same time. No damage or issues were to be found in any of the drive train from the gearbox back. I was inclined to think, is it a possibility the driveshaft could be unbalanced. As that could only be checked/detected on a proper test rig.
i'll keep an eye on mine, see how it goes. I do the interim oil changes on the Bike so at the next service i'll send the oil off for a check and see if there's anything untoward in there which would signify a failing component.
When i spoke to a local independent that's what he said - ride it, unless it starts to get worse. He's not heard of any manufacturing failings/common issues on these 'boxes, and it's a high cost (time & labour) to remove it all out, and then £££ to replace things anyway simply because its now apart!
Hi guys. My new GSA has been having nearly identical problem since I bought it new with 6 miles on the odometer. Unfortunately I made a mistake of not test riding this bike because it was raining but I did ride an identical bike earlier and it was butter smooth, no weird vibrations.
Of course I took this bike to the dealer. Their master BMW mechanic rode it but said it was perfectly fine. He said I should try riding with engine RPM above 4000 RPM most of the time ( bull crap, in my opinion). Everything is normal to them unless it doesn't run at all or something falls off the bike.
Another abnormality I noticed was some tapping felt in the foot pegs and the seat when accelerating at lower speed. It kind of feels like a small rock got stuck in the rear tire. I can also feel like there it something slightly loose when going over small bumps while clutch is engaged and accelerating slightly.
Another observation. In the LOW suspension setting, the bike rides smother, with less weird thrumming and tapping felt in the foot pegs. The drive shaft runs at a lower angle in this mode.
So, I believe the problem is in the driveshaft not seating properly on the transmission output shaft splines. It's either caused by a weak or defective C clip that should lock the drive shaft on the splines or a defective drive shaft. I opened the front driveshaft housing rubber boot ( cut the wire tie and slid the hood sideways to see the driveshaft). A quick inspection revealed that the drive shaft has about 1/8" (about 5 mm) forward/aft play. I can easily push it forward and back with my finger. I don't think it should move this much. It should be locked by the lock ring (C clip).
If you want it done right, you have to do it yourself. I don't have a new C clip but I did remove the shaft, pried out the existing C lip and bent it a bit with pliers.
Reinstalled the driveshaft. The free play was reduced by half. I took the bike for a ride. The tapping was barely noticeable. The vibration was basically gone. No more annoying vibration at 75 MPH at 4500 RPM.
Unfortunately the vibration came back after about 50 miles. A quick inspection revealed that the drive shaft play was back to a bit over 1/8".
I ordered a new C clip and have been waiting for it. I'll replace it and hopefully the problem will be fixed. If not, the drive shaft may have to be replaced due to improperly machined groove for the C clip. I'll let you guys know the results but wanted to post my findings to help you remedy your similar problems.
I'd be curious if any of you have checked the fwd/aft free play in the front splines on your drive shaft? I don't think there should be much play at all. It's very easy to check as I described above. Takes maybe 5 min. You'll need. New plastic wire tie, sold everywhere. Just make sure it's long enough. Take the old one with you to measure length.
Hope this helps. My engineering brain just could not believe the vibes and tapping was normal on a $30,000 bike.
