If its seized on the rear shaft bike will still run although the final drive shaft moves slightly on the front shaft. The movement is very small because BMW seem to have found a geometry that means the shaft is not constantly expanding and contracting - that said it does put stress on the shaft and the free rotation. I have a 2016 GSA (23000 miles and the final drive gaiter was in perfect condition) and the rear shaft was seized solid. So much so I had to drop the final drive off completely and remove the FD shaft from the front splines. Because I didnt want to stress the FD input bearings and shaft too much after basic attempts at separation the only way I could find was to use freeze spray (a penetrating oil) over 2 days to get the 2 surfaces to crack. I have to be honest the only other once it has got so bad (that I have seen used on YouTube vids) is to then cut the outer UJ head and then use a Bearing Puller to get the final part of the UJ off. Thats a complete new shaft required to rebuild so its worth persevering.
I was finally lucky and could split mine - after hours cleaning with a dremel circular wire head and wire wool I got mine back to std. Once rebuilt it is now fine but what I did notice is that the back wheel always used to run "lumpy" almost awkward and with some resistance - this is not the case anymore it now runs as smooth as silk.
Thinking about how smooth it now runs compared to before I would be interested to know if I get any fuel saving when I finally get to run it - I doubt it because the rubber stress joint in the final drive would have probably taken most of the "resistance" out of the process of delivering drive??
What I would say is that never again will I own a bike that I dont get to know a little better - in other words I will do the spline lubrication as part of the annual self service (the dealers wont do them) because it is a few quid in parts and a few hours of time. When I look at the state of the drive on my bike (2016 well looked after, good gaiter protectors, never pressure washed, and never off roaded or ridden in deep water) then I suspect that any Lubrication at the factory on build up was a courtesy wipe over with a Greasy Molly rag. I reckon the best time to do the Lub would be before every scheduled Final drive oil change and then the dealer is dropping the oil (although you have to drop the oil anyway during the process but at least if you did it days before then you could replace the same oil and the seals and let the dealer change them days after.
if you really want to make the job easy then find a BUNG for the ABS speed sensor hole in the final drive during the process then you wouldnt have to drop the oil.
Rik
I was finally lucky and could split mine - after hours cleaning with a dremel circular wire head and wire wool I got mine back to std. Once rebuilt it is now fine but what I did notice is that the back wheel always used to run "lumpy" almost awkward and with some resistance - this is not the case anymore it now runs as smooth as silk.
Thinking about how smooth it now runs compared to before I would be interested to know if I get any fuel saving when I finally get to run it - I doubt it because the rubber stress joint in the final drive would have probably taken most of the "resistance" out of the process of delivering drive??
What I would say is that never again will I own a bike that I dont get to know a little better - in other words I will do the spline lubrication as part of the annual self service (the dealers wont do them) because it is a few quid in parts and a few hours of time. When I look at the state of the drive on my bike (2016 well looked after, good gaiter protectors, never pressure washed, and never off roaded or ridden in deep water) then I suspect that any Lubrication at the factory on build up was a courtesy wipe over with a Greasy Molly rag. I reckon the best time to do the Lub would be before every scheduled Final drive oil change and then the dealer is dropping the oil (although you have to drop the oil anyway during the process but at least if you did it days before then you could replace the same oil and the seals and let the dealer change them days after.
if you really want to make the job easy then find a BUNG for the ABS speed sensor hole in the final drive during the process then you wouldnt have to drop the oil.
Rik
