Countershaft Sprocket Seal Leaks

**Mon Sep 16, 2013 7:11 pm » Post: #1 » Download Post**

Mine is weeping just a bit. New OEM (I think) seal. Fresh rebuild. Will this seat in and stop leaking? I have a few hours on it now.

If not, I'll give a new seal a try. The shaft was a bit rusty outside the seal. I polished it on the wire wheel. Perhaps it has a small bend?
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

**Mon Sep 16, 2013 11:03 pm » Post: #2 » Download Post**

You say "fresh rebuild".
Does this mean a new bearing right next to the leaky seal?
If so, did you remove the side caps/seals on the new bearing?

I think you will find that gearbox oil gets delivered to the LHS of the bearing and if the side caps/seals of that bearing were not removed when installed, it causes the sprocket seal to leak.
You will need to pull out the cassette gearbox, (leaving the motor in the frame) and pull that bearing out I'm afraid.

Or it may just be a leaky seal? Lets hope so.
_________________
[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

**Tue Sep 17, 2013 11:12 am » Post: #3 » Download Post**

Bearing was not replaced. It did not have any "felt" play. Nor does countershaft have any "felt" play.

Though I did not know a new bearing would have seals that would need to be removed. Good to know. Thanks.

I'll order up a new seal and give that a try.
_________________
MC21R9N track
MC18R2J track
CBR954
CR250

**Tue Sep 17, 2013 9:20 pm » Post: #4 » Download Post**

Sometimes the seals garter spring can jump out of its seat when installing the gearbox. Catching on the sprocket retainer groove can cause it.

I've seen a video of some factory mechanics stripping and rebuilding a bike.
They fitted an o-ring to the groove when installing the gearbox.
Then removed the o-ring afterwards, before fitting the sprocket.

**Tue Sep 17, 2013 10:41 pm » Post: #5 » Download Post**

It's also easy to nick the seal on the sharp edges of the shaft when refitting the transmission. A little masking tape over the splines will prevent that from happening.

Seen loads of seals leaking after the sharp edge of the sprocket retaining collar groove has caught the lip of the seal and damaged it.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!