Final drive maintenance

[DeeG]

How much of a chore is it to crack open the final drive and inspect the bearings?  I'm concerned about the condition of the bearings based on what my swing arm and rear wheel bearings looked like.  And I noticed some blue sealant of sorts peeking out from under the housing cover. 

At the least (no damage to bearings) I would need a new gasket. 

#2 in the drawing.  Would I also need #3, the gasket ring?

[georgesgiralt]

Hello,

Having my splines badly worn, I bought a second hand rear drive. It was so cover with muck and oil that I decided to crack it open and change all seals.
It is not a very difficult job if you have the tools to lock the input arbor while removing the nut. Do not forget to change the seal under the input pinion.
And the lip seal on the castellated big input nut.
Use a torch or a heater to heat the housing in order to have the needle bearing out. (there is a lip seal under it).
All in all I spend an enjoyable afternoon looking at that fine piece of work.
Hope this helps.
P.S. the needle bearing under the crown has two oil passages. They where to the crown on my drive. I've learn that you can put them in the other way...

[Tony Smith]

Motobins sell a kit with  all gaskets and seals needed for somewhat less than the parts individually would cost.

If you need to replace the big output bearing, buy the same brand bearing and you may avoid having to re-shim it, at least that's how it worked out on the 2nd hand final drive I rebuilt recently.

[Bob_Roller]

A little tip, the paper gasket between the cover and final drive case, it only goes on one way figure it out before you add any sealant to the gasket .

[Tony Smith]

A little tip, the paper gasket between the cover and final drive case, it only goes on one way figure it out before you add any sealant to the gasket .

Yep it only goes on one way. BUT, do not use sealant on it, it is enough of a bastard to clean the mating surfaces (as you are shortly going to discover) without also having to scrape sealant off - this one, like a number of airhead gaskets, does not require sealant, what it does require is scrupulously clean mating surfaces.

Also, if you do find yourself in need of re-shimming, when you take a deep breath to buy a selection of shims (they are expensive little suckers), then buy a couple of extra gaskets as you will find that the process of torquing the cover and then removing it to inspect the bearing blue will quickly destroy the gasket.

[Bob_Roller]

I work in the commercial aviation industry, found a material, parting compound, put it on the metal surfaces, then put sealant on a gasket .
When you take the parts apart, the sealant and gasket just peel off .

[Tony Smith]

Sound great Bob, but why use anything when none is required?

[Carott]

DeeG,

Unless you have some indication of a problem I would not open the final drive just to inspect it.
If the drained oil is free of metal particles, not brown in colour (water in oil), of a volume close to 250cc and there have not been any strange noises or substantial oil leaks, leave it alone.
The swingarm and wheel bearings are subject to more abuse as they do not give the owner any indication that the seals have failed unless the owner is inspecting them during regular maintenance.
The final drive bearings are inside a sealed oil bath and will give ample warning of seal failure before any damage to the bearings.

Brett

[mrclubike]

Use the Quad rings instead of the standard O rings on the brake shaft
Way better and cheap
And i have heard to lower the fluid level a bit

A was hassled with a leaking brake shaft until i install the quad rings

[mrclubike]

Here is the Mcmaster Carr page
https://www.mcmaster.com/#o-rings/=1efj2wd