Boxerworks.com

1984 R100
I've been putting off lubing my tranny input spline because I've been busy with other projects. The action of the clutch is smooth and easy to operate. Does that mean that all is well and I can wait? I'd like to ride the old tank, but guilt about not checking, and fear of what may happen if I don't, has me in a quandary. I know, this is a good problem.

Splines on automobile manual transmission input shafts are not lubed, why must BMW motorcycle input shaft splines be lubed? Someone please explain this.

ZM, if you have no symptoms of a balky clutch there is no need to fret over spline lube just because x mileage has accumulated since the last lube job. RIDE!

George Ryals wrote:Splines on automobile manual transmission input shafts are not lubed, why must BMW motorcycle input shaft splines be lubed? Someone please explain this.

Aren't auto transmissions lubed by oil coming down the tunnel at the back of the transmission? There's an oil seal at the rear opening of the tunnel.

Kurt in S.A.

It is my understanding that the trans input shaft of "earlier" models weren't plated and would wear if they weren't periodically lubed. Later bikes (I believe including my 94 Mystic) had different input shafts that didn't require lubing as frequently.

According to this, the cutoff is when they went to the monolever and at that point every 30k instead of 10k miles.

http://bmwmotorcycletech.info/inputsplinesthrowout.htm

It was a huge difference in clutch action when I lubed the splines for spring 2015. Very heavy before. Smooth and happy after.

If things still feel good, I'd leave it.

I lube the clutch splines on the VWs also, although it isn't called for specifically.

The clutch splines on the /2 were never lubed and didn't need it. The teeth were very large and if the transmission was centered, they didn't wear. Many people didn't center the transmission, so they would wear as a result.

The advent of the /5 with the very thin teeth required some lube to greatly reduce the wear and extend the life.

Some bikes would have a grabby clutch, Many thought it was due to lack of spline lube and some may have been. Mostly it was a matter of having the correct end play of the input shaft by using the correct shims. In 1970-71, that was a factory error. In 72 they were OK, but some rebuilders didn't know the how/why and screwed them up.

The /5 and later were automatically centered.

Does this answer your question about spline lube? All this is on my website.

Kurt in S.A. wrote:

George Ryals wrote:Splines on automobile manual transmission input shafts are not lubed, why must BMW motorcycle input shaft splines be lubed? Someone please explain this.

Aren't auto transmissions lubed by oil coming down the tunnel at the back of the transmission? There's an oil seal at the rear opening of the tunnel.

Kurt in S.A.

None that I've ever changed a clutch on were lubed like that. I clean and lube the splines on cars and trucks when I change the clutch or pull the tranny for any reason, but I don't do it any more often than that. They generally have thicker, stronger-looking splines than our airheads.