New sleeve gear is larger then my old sleeve gear

I purchased a new sleeve shaft gear from a guy how had new old stock. I installed it but it fit too tight against the mating gear.
It was very hard to turn. I remove the new gear sleeve gear and compared it with the old sleeve gear. Using a micrometer I found the new gear was larger in diameter then the old gear. New gear was 2.591" vs my old gear at 2.536". Both gears have 23 teeth. The shaft size was the same for both gears, just the gear size was different.
Question: What transmission would this new sleeve gear fit. It looks the same as my old gear only the gear is larger then the old one?

I forgot to mention that I have a 1971 Norton with the stock 4 speed transmission.

A lot of this NOS stock is recovered from the reject bin and the fault is not discovered until someone tries to fit it. As the bearing it fits in has a nominal bore of 2.5" 2.591" is too large, not aware of the bearing changing over the years. You can get the gear bearing journal ground down to suit the bearing.

"too tight against the mating gear"


You need to get another one.. and it's mate.

nortonisthebest said:

Using a micrometer I found the new gear was larger in diameter then the old gear. New gear was 2.591" vs my old gear at 2.536". Both gears have 23 teeth. The shaft size was the same for both gears, just the gear size was different.
Question: What transmission would this new sleeve gear fit. It looks the same as my old gear only the gear is larger then the old one?

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The sleeve gear tooth form (along with layshaft "4th") was altered in late '68 (from eng. 128646) so it's possible what you may have been sold is the earlier (040422) sleeve gear?

Edit: 2.536"-2.537" would be the correct diameter for the later (061057) sleeve gear.

The earlier 4th gear sets were 24 teeth and 18 teeth.
If a 23 tooth is oversize on its OD it is probably totally wrong in its pitch diameter and should be returned to the person who sold it to you and a refund demanded. Mind you as old Ted Bloomfield of Motor Cycle Shop would say....British bike owners very rarely return bits that are wrong, they either bin them or put them on a shelf and forget them.

J. M. Leadbeater said:

The earlier 4th gear sets were 24 teeth and 18 teeth.

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The 24/18 4th. gear set was used up to 1960. This is different again to the "early" (pre-128646) Commando (late Dominator, Atlas etc.) 23/18 4th. gear set.

I contacted the gentleman that sold me the sleeve gear and gave him the measurement off my old gear. He found another NOS sleeve gear from his old stock that was the same diameter as my old gear. I will send the sleeve gear he sent me back to him and he will be sending me another one with the correct gear size of 2.536"