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Gearbox Oil Leaks

A review of correspondence from NOC-L

How to stop oil leaks from the kickstart and gear lever


Quad ring modification

It is quite possible to modify the covers to take a lip seal, but it requires some skill with a vertical mill. However, you might try removing the standard O- ring, and replacing it with a 'Quad' ring which has a sort of rectangular section. This is because it appears to be moulded from 4 thin O-rings, which are stacked to make a square section (hence the name). You can find Quad rings at hydraulics repair shops. When you install them, thoroughly clean out the recess, and seal the ring to the case with silicone, or another good sealer.

Greg Kricorissian ( on NOC-L26th. Sep 1997

Quad rings - recommended

Phil Radford at Fair Spares, San Jose, CA., installed seals similar to the Mk.lll in my outer cover; they seem to work fine.

Greg Nolan ( on NOC-L 26th. Sep 1997

Gearbox cover seal modification - a source

Fair Spares, U.S.A. has a fix listed in their catalogue that requires you to send them your cover and they fit the proper seals. I believe it requires some machining but overall seems quite painless. I'll be going that route.

Jeff Schneider ( on NOC-L 27th. Sep 1997

Gearbox cover seals - a product recommendation

The O-ring on the kickstart shaft can be replaced by a proper oil seal. The one I use is TCM (brand) # 10121VM. To install it you must heat the outer case to release and reinstall the steel bushing. The kickstart shaft should be free of burrs or grooves for this to work.

Pete Serrino ( on NOC-L 26th. Sep 1997

Gearbox cover seal modification - very successful

I wrote looking for a solution to gearbox leaks. Greg Kricorissian suggested fitting a 'Quad' ring in place of the O-rings. I have done this on the kickstart shaft and it is a complete success.

Chris Ghent ( on NOC-L 29th. Oct 1997


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