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Gearbox grease

Submitted by keith_brown on Mon, 06/08/2012
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Commando

Just had the outer cover off the gearbox of my 71 to replace weeping oil seals. I noticed that the selector mechanism had quite a generous coating of grease on it. Also internal nuts and bolts above the 1 pint oil line had a fine coat of rust.

Can anyone tell me if it is normal to grease the selector mechanism or is the gearbox oil supposed to find its way to lubricate these internals?

And why on earth would the cover be assembled with slotted cheese head screws? Is that to stop the cover being over tightened?

Submitted by keith_glassborow on Tue, 07/08/2012

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Someone was in there before you!I've always assumed it's lack of use that causes the corrosion. Damp air just loves cold metal and if the bike isn't used those surfacesdo not get coated regularly, displacing the moisture. Mine was particularly bad but regular use improves the situation.Never considered greasing but it's a good idea. Yes, those cheese head screws loved by Brit bike designers!Most fit socketbolts but not for concours of course!!

Submitted by colin_sharpe on Tue, 07/08/2012

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Cheese head screws were original fittings on Norton gearboxes. I once asked John Hudson why Norton had not moved to socket head cap screws, and he said that socket head cap screws would lead to over enthusiastic owners stripping the threads out of the aluminium cases. Considering Norton used BSF screws to hold the covers on, he probably had a point - I could never understand why Whitworth screws were not used for screwing into aluminium.

Submitted by keith_brown on Tue, 07/08/2012

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Thanks for info guys. Does 20 years in a shed constitute lack of use? :) I have cleaned and reassembled with light coat of grease on parts above the oil line. Slotted cheese heads are cleaned and returned. Maybe I will shorten an allen key and replace with cap heads at some point.

Submitted by david_evans on Sat, 11/08/2012

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It's common to find the outer case of Nortons full of rust coated components. Water runs down the clutch cable and into the outer case and any condensation that forms will play havok with the unplated selector quadrant and other "stuff" in there. The gearbox "breathes" through the cable entry point, though for some obscure reason the Mk3s had a little breather fitted to the case. I would coat all the bits in there with a layer of grease or some kind of oily wax (waxoil even)

Submitted by keith_brown on Sun, 12/08/2012

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Thanks David, nice to know it's a common occurrence. I wasn't sure how hot the gearbox ran and was a little unsure if I would be contaminating my nice clean gear oil by greasing. My box had half a tub of lard coating the selector. I've cleaned and given everything a light coat of high temp lithium grease.

Interesting about water running down the clutch cable, I will pay attention in this area when I redo the clutch.

 


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