transmission variations

There are a few changes that happened inside the box. I have a few gear sets and surplus gears. Is there anything written down about the different gears and how to spot them by number of teeth and measuring. I know a little bit about the AHB markings and the groove cut in the second gears as indicators. Some of these letter stampings are not clear.

Commando or all AMC gearboxes?

1966 to 1975

The information I have is for the Commando.

1st., 3rd. and 4th. gear ratios didn't change although the sleeve gear and layshaft 4th. were changed from serial 128646 due to a revised tooth form so are dimensionally different...

...I don't know what markings - if any, the pre-128646 sleeve gear and layshaft 4th. had.

The 128646-on sleeve gear is marked 'AH', with a '6' or '9' on layshaft 4th.

Stronger 3rd. gears were introduced from serial 133488 and both marked 'AH'.

2nd. gear ratio changed from 18/24T to 18/23T from 306591 on the 850 Mk1A and later (Mk2, 2A & Mk3) models. Marked AHB with the grooved dogs. The original 18/24T 2nd.gear pair is marked 'AHA' by Andover Norton but presumably originally marked 'AH'.

The single (outer end) circlip sleeve gear 064991 was introduced as far as I know on the Mk2/2A, also marked 'AH'.

Twin circlip sleeve gear 065854 as far as I know, was introduced on the Mk3 and marked 'AH...3'.

Any gears marked RSxx are not genuine Norton.

That is great info LAB. To have changes by engine number,as compared to listing of Layshaft 2nd gear - old type, or later type like from Fred's site. https://www.nwno.org/resources/OldBrittsWebsite/ob_1270.htm

Is there a simple list for the Commandos that has engine/gearbox changes by year or engine number?
I see Terry Macdonald has one like that for the Bonnevilles:

Triumph modifications/differentials by engine number 1963-83​

YukoNorton said:

That is great info LAB.

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YukoNorton said:

Is there a simple list for the Commandos that has engine/gearbox changes by year or engine number?

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Not that I know of.

I don't know how you do it L.A.B. My mental picture is you sitting at a huge desk surrounded by massive walls full of reference books and original Norton factory drawings, patents and work procedures. You get an e-mail request, stroll over to the correct shelf, pull out the desired material, adjust your glasses and provide incredible detailed information on 50 year old machines. I remain a fan!

"...adjust your glasses and provide incredible detailed information on 50 year old machines....

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I agree AC... perhaps L.A.B. is the man to create that technical reference for all...

"list for the Commandos that has engine/gearbox changes by year or engine number"

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Atlas Commando said:

I don't know how you do it L.A.B. My mental picture is you sitting at a huge desk surrounded by massive walls full of reference books and original Norton factory drawings, patents and work procedures. You get an e-mail request, stroll over to the correct shelf, pull out the desired material, adjust your glasses and provide incredible detailed information on 50 year old machines.

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Actually, a very small desk and files are generally on computer plus I have a few 'Norton' books.

YukoNorton said:

I agree AC... perhaps L.A.B. is the man to create that technical reference for all...

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It's a possibility.

The
Norton Commando Service Releases (Updated 06/13/22 )
I saw on Greg Marsh's site are 7 pages of notes on changes to the Commando, many with reference to engine/vin number:

A minor update, at s/n 147846 toughened kick-start pawls were introduced. Should have a little M marked on the side.

Deckard said:

A minor update, at s/n 147846 toughened kick-start pawls were introduced. Should have a little M marked on the side.

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yup;