The splines on my drive shaft and final drive unit are badly worn, so I will have to replace both shortly. The current shaft is a 16 spline unit. Does anybody know if the splines at the gearbox end are the same on the 16 spline and the 20 spline drive shafts, or are they different? Since I need to replace both the shaft and final drive it would give me more choice of used replacements if the gearbox ends were the same.

i think they are 20 spline avenger .....recently i changed a 16 tooth for a 20 tooth spline drive shaft and a 20 spline bevel box . mated up just fine .

bit worried about the looseish fitt with the 20 spline model pinion diff to shaft though , the 16 tooth was sweet and tight by comparison

good luck mate

Hi Charlie, did you just swap the 16 spline shaft and bevel box for a 20 spline shaft and box, and keep the original gearbox?

yes mate.... its all good

Gear box end are all the same, it's just the rear end that differs. Try and find a 16 spline diff and driveshaft, they do not wear anywhere as much as the later 20 spline units. I can not for the life of me work out why BMW changed from 16 to 20, the 16's just do not wear out whereas the 20's wear badly. I was chatting to motobins a couple of months ago and they said that they rarely see good usable 20 spline driveshafts, but normally have a number of good 16 spline shafts available.

Thanks for the replies, I suspected that the gearbox ends were the same, just didn't have one of each to compare. Mine is a 16 spline and the splines on the bevel box are bad, worn to a point with a ridge on them. Since I am using the bike locally, I will chance it for the moment, but I am looking out for replacements. I am after a damaged 100RS at the moment, but when I contacted the number in the add I got the owners son and he didn't know whether it is an 8 valve or a 16 valve bike or what year it is. Mind you to buy a 16 valve and change the gearbox and fit the paralever rear end might be interesting.

i think they changed to 20 spline some time in late 86 ...one thing to look out for is the gear ratios on the bevel box ...(there stamped on the box about the square section near the bevel /verticle part under side from memory )

theres a few out there avenger ...

one thing to look out for is the gear ratios on the bevel box

Thanks Charlie, I'm aware of that, but wouldn't mind fitting a RS bevel box to gear it up a bit.