chain case bearing seal

[stomper]

I pulled the chaincase off of my 06 attack and noticed that one of the seals on the bottom bearing (drive shaft bearing) was removed. I realize that it was probably removed so that the bearing could get lubricated by the chain case oil and that this is a common practice on some sleds. The thing that confuses me is that it was the outer seal (towards the engine) and not the inner seal. Shouldn't it have been the seal that is faceing into the chain case instead of away from the chain case. Or maybe both of them remove. Both seals are removed on the jack shaft bearing. After all there are seals on the chain case housing.

 

[Yamadogger]

The way you noted is correct - seal removed on the engine side. The bearing still gets lube due to the slip fit of the bearing inner race onto the drive axle shaft. It's kind of an ingenious "filter" of sorts as the fairly tight clearance keeps out large contaminants but still allows oil to get in. I know others have removed the opposite seal with the thought that the bearing gets more lube since it's directly open to the oil but the bearing then sees more contaminants in the oil. The upper bearings are open because they only receive oil that's thrown up there by the chain and this "filter" system would likely not allow enough oil to pass on these bearings. I know this topic has been discussed many times on this site and there are many opinions of the best way to do it. Personally, I've run pretty much every combination and had the best luck with it the way it comes from the factory. I even went as far as to run double sealed bearings on the bottom of my SRX as a little trial and that worked pretty well too. No contaminants can get in and there's about zero chance of moisture getting in. I ran many seasons with this set-up.

 

[stomper]

Cool, it will stay the way it is then. Just thought I would check.
Thanks

 

[Bradford]

Now, that makes sense. Just wish I knew that when I reassembled my chain case this fall. I questioned it putting it back together and ending up reinstalling the bearing with the non seal side to the outside. It will stay that way for the season