Ariel Owners Motorcycle Club

Iv just dismantled the gearbox on my scruffy NH 350 as it had some some serious end float on the mainshaft
..After looking at it all the dogs and the teeth they all look good but never having never been in any gearbox of any description I'm out of my depth. I ordered a 6303 bearing at the suprisingly cheap price of less than 3 pound it comes on monday
I turned my attention to the rest and there was no washer or shim between the last cog on the main shaft and the aluminium casing.. it just seem right. As the cog can rub straight on the casing. And I was sooo careful when I dismantled it but I might have messed up and missed it. Can you enlighten me if this is correct please anyone
Iv tried looking at exploded diagrams on the net and I can't get anywhere

Also there was a tiny piece of aluminium which was in the bottom of the casing
Pictured next to .the bearing

Burman's did not use shims or spacers on the GB. Mainshaft end float is controlled by the k/start ratchet bush. It may be worn although it is kin hard. A shim can be used here but if very thin is unlikely to survive. End float should be around 1/64 but is not critical as the intention is to ensure that the shaft doesn't bind. I think the bush should be .861" long

Hi

The gear shouldn't touch the aluminium case, it should be held in place by the bearing inner when the kickstart mechanism is torqued up.

That bit of 'alloy' looks like it may be a trumpet nipple, or a part of one, from the clutch cable - just a thought.

Regards Mick

Edited to add, I hope you ordered a 6203 bearing and that the 6303 was a typo.

Thank you mick. I'll wait for my bearing on Monday and attempt to put it back together.
I need this as my winter bike. Iv decided if it ain't British I'm not riding it

Rick Hughes wrote: Fri Nov 06, 2026 4:00 pm ... decided if it ain't British I'm not riding it

Good for you. They get you like that.