Jackshaft Bearing - Chaincase Side

[Attak-Firecat]

Does anyone know for sure whether the top bearing on the inboard side of the chaincase gets greased? It appears that gear lube from the chaincase is doing the lubrication for this bearing, but the inside seal on the bearing seems like it would prevent gear lube from getting into the bearing. On disassembly, the bearing was clean with gear lube in it and no grease. Is this right? I'm paranoid that I'm going to lose that bearing. Thanks in advance.

 

[APEX 06]

They come with a gease in them new.

 

[WinderFab]

Attak-Firecat
no grease, the gear oil does the job, the seal is to keep the bearing clean from any metal that may be in the oil, the seal lets in gear oil that's why you seen oil in there when you took it apart,

i could be wrong but i have only seen this when i opened up my chain case on apex, older sleds don't have seals in the chain case on oil side,

when i changed my bearing in my apex a few years ago i removed the seals on the oil side like others did on this site and about 7k later with no problem,

the seal is cheap insurance just in case a piece of metal get's in the oil,

 

[Blue Dave]

The upper (jack shaft) bearing in the chain case should have no grease seals on either side. The lower (drive shaft) bearing should have a seal on one side.

This lower (drive shaft) bearing orientation is where there are some differences of opinion. The factory installs this bearing with the seal facing inwards probably to protect against metal infiltration especially when the gears and chain are breaking in.

My opinion is that when replacing the lower (drive shaft) chain case bearing with a fully broken in chain and gears you should install it with the seal facing outwards. My Yamaha dealer agrees and installs replacement bearings this way. My reasoning is if the chain and gears are fully broke in and you change your gear lube yearly I think that this bearing is better off being bathed and flushed with fresh gear lube than to have old gear lube trapped in it that does not get changed with a lube change.

However as I stated at the top this is a moot point for the upper (jack shaft) bearing as it is not supposed to have any seals. Same for the upper (jack shaft) bearing on the chain case cover. The only bearing in the chain case with a seal is the lower (drive shaft) bearing.

Here are a couple of links to previous threads related to this subject:

http://www.ty4stroke.com/viewtopic.php? ... ht=bearing
http://www.ty4stroke.com/viewtopic.php? ... ht=bearing