I find that even with nothing fitted, the mount blocks the top of the rev counter. With something fitted, I can lose the top of the speedo and the rev counter is hidden. Any recommended product to raise the satnav mount? I’m in the UK so would prefer something from UK or Europe.
Some motorcycles use shaft drive rather than chain drive. In addition to the hinge point near the gearbox, modern designs have a second hinge point near the axis of the rear wheel. This is done so that a parallelogram linkage can be used to isolate the suspension from the effect of engine torque - without it, you can lose a significant amount of ground clearance if you back off the throttle in a corner. Externally, the rear hinge point is implemented as hinge in the shaft casing. Internally, the shaft has a simple universal joint in all cases that I have seen. While there is another UJ at the front of the shaft, the two do not operate together as a conventional constant velocity joint because the two points will commonly bend in opposite directions.
The rear UJ does not run in the oil bath of the rear bevel box because it has to move around, and depends on grease fitted at the factory. It is a known weak point: if the joint overheats and seizes, it can break, letting the remaining shaft thrash around and break the swinging arm, which can detach the rear wheel and introduce a sky-ground-sky scenario. BMW have introduced a free mileage-based replacement of the shaft for life on some models, and the problem is known to happen on other makes. While using a double Cardan joint would not solve the lubrication problem, it is said to be more suitable for high articulation angles. These tend to happen on bikes due to varying load and suspension movement. The shaft casings are made to have a large amount of internal room at this point to accommodate movement, so fitting a larger joint doesn't seem to be an obvious problem.
So in brief: is there some reason why simple UJs are used rather than constant velocity joints?
No photo - I couldn’t get my phone in to camera mode before it dived. As far as I could tell, it had external ears, so I think it was a sea lion.
