Norton Gearbox

Hi guys,

I am restoring a 72 Combat and I want to temporarily install a gearbox I bought years ago while I rebuild the original matching numbers box. The problem is I dont know if it is a working unit. It turns smoothly but I cant seem to shift the gears on it. Should I be able to shift the gears and find nuetral without the gearbox installed on the bike? It seems to be in gear because when I use the kick start lever to turn it over the drive sprocket turns with the mainshaft. When I move the shifter up and down it moves freely but does not seem to engage a new gear or find a nuetral position. I guess I am hoping that there is a way confirm that the unit is at least functioning before I Install it. Any feedback appreciated.

Regards,

Gordon

You should be able to find neutral. From what you describe it sounds like something needs tending to inside the first cover. Often times moisture leads to corrosion of the spring and paul mechanism.

A service manual would be handy for this but not essential as board members can walk you through this based on what you see and report back.

You should be able to cycle through the gears while turning the main shaft on the other side. Things need to turn in order to engage or release. Turning the main shaft you will see the sleeve gear (the gear/shaft that the sprocket is atteched to) change rotation speeds as you change gears.

If needed and for what it is worth, because you have one out on the bench, checking its condition is quite straight forward. Once you have done it successfully once, it is a piece of cake to do again. And I will add, totally rebuildable in the bike.

Hi Guys,

Great advice and within minutes of posting.

I took the front cover off and discovered that the spring peg ( I think thats what they call it ) was on backwards so it was not engaging against the ratchet plate.

Put it back together and it shifted through all gears and neutral like a champ!

Lots left to do but there is light at the end of the tunnel.

Thanks again. What a great forum.

Regards,


Gordon

Gordon said:

Hi Guys,

I took the front cover off and discovered that the spring peg ( I think thats what they call it ) was on backwards so it was not engaging against the ratchet plate.

Put it back together and it shifted through all gears and neutral like a champ!

Click to expand...

Should be a flag of caution. The spring peg (or whatever you are looking at) being in backwards probably did not happen at the factory and certainly is not a matter of wear and tear so keep a critical eye open for other things that are not correct. My unfounded gut feeling is you have flushed out the gear box problems.

Does it have the Portugese lay shaft bearing?

Dances with Shrapnel said:

Should be a flag of caution. The spring peg (or whatever you are looking at) being in backwards probably did not happen at the factory and certainly is not a matter of wear and tear so keep a critical eye open for other things that are not correct. My unfounded gut feeling is you have flushed out the gear box problems.

Does it have the Portugese lay shaft bearing?

Click to expand...

My thoughts too. Do you intend to take a long time rebuilding the numbers matching gearbox and ride the bike in the interim? If you aren't sure the layshaft bearing in the used gearbox has been replaced, but you can be sure that it has been worked on by someone who shouldn't have, then do you feel comfortable investing the time necessary to install a used gearbox you can't really trust? Knowing, in addition, that you'll have to replace it again later with your rebuilt one?

An alternative is to open the used one and check/replace the layshaft bearing and eyeball everything else; but then you're doing an extra "rebuild" (even if it won't be of the same quality reserved for the original one).

None of my business, of course, and I'm not trying to second guess you, but unless you can't rebuild the original gearbox fairly quickly (for whatever reason) I'd not invest the time/money to deal with the used one, except possibly for parts and a later redo for a spare or resale. IMHO. :|