Chaincase Bearing

[nhrxrider]

If the seal was toward the case and the open side toward the drivers, then no oil would get onto the bearing until the seal was worn; then oil would leka out of the chaincase. Also, with the open side toward the drivers, dirt would get into the bearing. I wish I remembered my replacement bearings...I think I had double sealed bearings, but if I don't, then I would have installed the open side toward the chaincase for lubrication. Any particles in the chaincase oil would be minor compared to the outside dirt always getting into the bearing. Also, since there is no actual pump in the chaincase, most shavings would stay in the bottom of the case unless there were enough to get up to the level of the bottom of the chain...in which case, you have more to worry about than the bearings. As was already compared, its no different than the bearings in a manual transmission, which are open, and those don't have problems from metal shavings.

I actually think I would stick with one seal and put the open side toward the case. That will allow better lubrication than the double sealed bearings, which tend to go dry fairly quickly (a year or so) in an application where they see high speeds for long periods of time.

Jim

 

[az99]

There is no separate seal between the gear and the bearing. The seal is in the bearing facing the gear. The side of the bearing facing the tunnel is not sealed. There is a separate seal between the tunnel side of the chaincase and the open side of the bearing. I have no idea how oil gets to the bearing but it was very oily. That is why I asked the question. The other bearings are open toward the chaincase oil. It is too bad Yamaha can't afford to put a magnet on the dipstick like the other mfgs. The amount of metal on the end of my SD dipstick is amazing. That is the only reason the seal in made sense.

 

[RX1 Yooper]

Thanks 99,
As for magnets. You could epoxy an earth magnet on the outside of the chaincase.