AMC Gearbox serial numbers

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sjr
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AMC Gearbox serial numbers

Post by sjr »

Does anybody have data on the AMC gearbox serial numbers, which numbers in the series belong to which years?
SPRIDDLER
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Re: AMC Gearbox serial numbers

Post by SPRIDDLER »

Curiously, data on serial number progression doesn't seem to have been documented (or if it has I've not been able to find it), although I believe Don Madden (N. America section) has collated some numbers in a listing.
Some individual numbers have been discussed in various posts on the web but all I can find giving general identifying info is a post by Les Ward who was this club's dating authority back in (I think) 2011:

AMC gearboxes from 1957 are stamped M for Matchless/AJS and N for Norton, as the outer cases differed. Competition boxes have sometimes been stamped S and T, presumably for Scrambles and Trials, also R on some later boxes, but it isn't short for "Race" as they are from road bikes. From the early 1960s the designation goes to MA for Matchless and NA for Norton. G15 machines can have either NA or MA. Later P11s have the same number on frame, engine and gearbox. None have a date code.


The club dating service holds some records of the gearbox number on specific bikes.

As an side, we had a factory tester at our section some years ago who told us that several testers were given bikes with the first production AMC 'boxes and offered a fiver if they could break them. Obviously they tried very hard but not one of the 'boxes failed.
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burrage
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Re: AMC Gearbox serial numbers

Post by burrage »

The "R" on AJS and Matchless boxes indicates that it was fitted with a 17 tooth final drive sprocket and not a 16 which was standard. 650 CSR models were fitted with 17 tooth sprockets and are marked "R".
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Re: AMC Gearbox serial numbers

Post by mdt-son »

SPRIDDLER wrote: AMC gearboxes from 1957 are stamped M for Matchless/AJS and N for Norton, as the outer cases differed. Competition boxes have sometimes been stamped S and T, presumably for Scrambles and Trials, also R on some later boxes, but it isn't short for "Race" as they are from road bikes. From the early 1960s the designation goes to MA for Matchless and NA for Norton. G15 machines can have either NA or MA. Later P11s have the same number on frame, engine and gearbox. None have a date code.
The NA/MA designation was introduced for the model year 1963 (i.e., in September 1962) and indicates some detail changes. At this time the clutch was redesigned as well to be able to handle more torque, probably as a result of the G15Mk1 development.

Most of the P11 machines had the following stamped on its top lug: P11/xxxx. The very late P11 Ranger 750 from S/N 128646 to S/N 129145 had the same number stamped on frame, engine and the gearbox inner cover. Curiously, the letter M was stamped after the serial number digits (with a space in between), similar to the R letter mentioned above. Does anyone know what the letter M means?

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biggles
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Re: AMC Gearbox serial numbers

Post by biggles »

Picking up on this old post from 2018 does anyone know what the letter M after the gearbox number means. Also, I have a gearbox stamped MA 14170 G and would be interested to know what the G means?

JT
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Re: AMC Gearbox serial numbers

Post by biggles »

Picking up on this old post from 2018 does anyone know what the letter M after the gearbox number means. Also, I have a gearbox stamped MA 14170 G and would be interested to know what the G means?

JT
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ajscomboman
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Re: AMC Gearbox serial numbers

Post by ajscomboman »

M is pre 62 with standard early type spring (slides into a hole in the inner case), MA designates that it's an Matchless/AJS from 62 on with the later type kickstart return spring (has a spigot for the spring to wrap around and no hole on the inner case), no idea what the G or the M after the numbers means though.
peterg123
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Re: AMC Gearbox serial numbers

Post by peterg123 »

G or M after the numbers etc could be codes for the month and last digit of the year manufacturer.... Burman also did the same.
Jampotswaney
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Re: AMC Gearbox serial numbers

Post by Jampotswaney »

My 1950 18S is stamped G88 C 50, built March("C") 1950.
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clive
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Re: AMC Gearbox serial numbers

Post by clive »

Jampotswaney wrote: Sun Dec 19, 2021 10:46 pm My 1950 18S is stamped G88 C 50, built March("C") 1950.
The Burman CP and GB (Also known as B52) gearboxes were stamped with a letter for the month and the year, without the 19. The later gearboxes, known as AMC because they were built in house, were introduced in the 1957 model year, so from September 56 onwards. The AMC boxes did not have a year stamp and this thread is trying to sort out what the markings did signify.
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