Gearbox mainshaft oil seal (2013)

maylar · Jun 17, 2013

When replacing the oil seal on the gearbox mainshaft is it common practice to also replace the countershaft sprocket spacer that the seal rides against?

Thanks

Guido · Jun 17, 2013

I would say no. Unless the spacer is nicked up causing it to ruin the seal.

maylar · Jun 17, 2013

Not nicked, but slightly grooved where it's been rubbing against the seal for 40 years.

CanukNortonNut · Jun 17, 2013

Maylar,
From all the road grit fed into that area by the chain, the spacer can show signs of a groove. It is amazing that a steel spacer can get worn out from a rubber seal turning a slurry of road grunge for many RPM's. Put a straight edge along the OD and shine a light from behind. If you see light then I would replace it. It is false economy to replace just the seal and have everything back together and still have an oil leak. My two cents
Regards,
Cheers
Thomas
CNN

dynodave · Jun 17, 2013

Dave
If it looks perfect I would reuse it....I change the spacer 75% of the time. They are not hard and they are usually grooved and I don't like to go back in there for a cheap piece just to fix the oil leak.
been there done that

dave

luckyed · Apr 3, 2018

I'm wondering if it's possible to remove the old oil seal with the mainshaft and sleeve gear still in place? I've been fooling around with a spare gearbox before attempting the job on my bike. The seal is pressed in pretty tight and it's hard to get any prying leverage with the shaft in the way. Is there a tool or a trick that anyone knows about?

batrider · Apr 3, 2018

I think I've done this but it has been a few years...... Use a self tapping screw to screw into the side of the seal and use it as a handle to yank it out with vise grips.

luckyed · Apr 3, 2018

Thanks Batrider. Good thinking. I may give that a try. If so, will report.

batrider · Apr 4, 2018

I didn't think it up myself for sure. I think it might come from one of the old non-factory Norton manuals like Haynes or Chilton.

The Buckeye Rider · Apr 4, 2018

In other applications of this same design(front crank seal of Mercedes Benz diesel) the sleeve could be turned around and the seal would have a new unmolested area to ride on because the seal didn't ride on the center of the sleeve. Just a thought!
Ride On
Dave

eskasteve · Apr 4, 2018

If I'd gone through all of the hassle of removing the primary to access the mainshaft seal I'd replace everything including the countershaft sprocket, spacer, locking nut, and the locking nut retainer and screw. About $80 or so extra.

Fast Eddie · Apr 4, 2018

eskasteve said:
If I'd gone through all of the hassle of removing the primary to access the mainshaft seal I'd replace everything including the countershaft sprocket, spacer, locking nut, and the locking nut retainer and screw. About $80 or so extra.

Yessir, that’s how I’d approach the job too.

batrider · Apr 4, 2018

eskasteve said:
If I'd gone through all of the hassle of removing the primary to access the mainshaft seal I'd replace everything including the countershaft sprocket, spacer, locking nut, and the locking nut retainer and screw. About $80 or so extra.

If one could rely on the quality, ability to meet original specs and fit of all the new parts I might agree.

Gearbox mainshaft oil seal (2013)

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