The shafts are similar but small differences make them non-interchangeable. The 1100 and 1100s shafts are similar but the transmission spline is different. The overall length of the 1100S and 1150 shafts is the same but the joint will be in the wrong place, causing more sliding action as the suspension moves and possibly interfering with the swingarm.
Note the long nose on the R1150 driveshaft. This is needed to reach the output shaft, for the same reason that the hub on the clutch disk has to be longer to reach the input shaft: the six-speed transmission is shorter than the 5-speed one that the R1100 series was designed around, and this was BMW's solution. Later 6-speed bikes, like the R1100S and K1200RS, were designed around the shorter transmission and therefore didn't have these extensions.
5-speed transmissions from the R1100RS/RT/GS/R have 16-tooth output shaft splines whereas the 6-speed transmissions (including the 5-gear versions in the R1200C and K1200LT) have 20-tooth output shafts. This obviously changes the spline at the front of the driveshaft.
The two complete driveshafts below are shown properly phased (the U-joints are mirror images at each end). This is important for reducing vibration.
|Top to bottom: R1150, R1100S, R1100.|
R1100 driveshafts were changed during the production run. Early shafts had an unsplined nose on the stub which simplified engagement, but the female portion had to be longer to compensate. The stub is nearly bottomed out in the shaft during operation.
|Top to bottom: early R1100, late R1100/1150 stub splines|
|R1100 5-sp||26 11 2 311 847||42||188||323||none||Obsolete, used with early end|
|26 11 2 325 747||42||188||304||26 11 2 332 547||16t trans spline|
|R1100S||26 11 2 332 997||42||195.5||300.5||none|
|R1150||26 11 7 655 802||55||195.5||289.5||26 11 2 332 992||longer nose|
|R1150GS Adv||26 11 7 671 303||keyed|
|K1100||42||232||250||16t trans, 20t pinion|
|K1200RS||26 11 7 663 759
26 11 2 332 995 E
|K1200LT||26 11 2 332 996|
Dimensions in mm. All have 20t final drive splines. R1100 has 355mm swingarm.