AMC transmission

I bought a G 80 bare bones basket case a few years ago in one of my weaker moments and I have a question about the trans. The number on the trans is M 35481 and the last letter looks to be an X but it looks more like a teepee and above the 5 it looks like a 1 but it doesn't resemble the 1 in the serial number it looks to straight to be a scratch and it has 16 teeth on the sprocket any idea what this trans might be?

Mark

Depending on what year your G80 is it may be either Burman CP or Burman B52, the CP for the 40's and early 50's followed by the B52 which finished during '56 and followed by the AMC [Norton] Box in 1957.

possm said:

and followed by the AMC [Norton] Box in 1957.

Click to expand...

As has been discussed in the AMC eGroup lately, the AMC gearbox was actually a design and manufacture of Plumstead. Norton bought the Sturmey-Archer design in the 30's and brought out the "Laydown" gearbox for 1949. The AMC gearbox is an evolution of the latter but there is no commonality of parts. Hence, it is correct to say ".... followed by the AMC [Matchless] box in 1957."

https://www.accessnorton.com/NortonCommando/what-is-the-lay-down-transmission.16046/

-Knut

M35481 sounds like the serial number of an AMC gearbox. Please post a picture.

-Knut

Thanks for all your input. I figured the M was for Matchless but didn't know what the X was or whatever that mark is. As far as I know the bike is a 62 it has the CS style fuel tank on it but I'm pretty sure this bike was thrown together out of whatever parts that was laying around. Could there be any other numbers or identifying marks on the trans I should look for?

Mark

Not that I am aware of. Introduced for the 1957 season, the AMC gearbox was improved for 1960 and again for 1962. Serial number progression of gearboxes probably exists somewhere, but isn't retrievable at this time. Your best chance of dating is to order a dating of your frame and/or your engine, hopefully the trans belongs to one of them, or both. You may take a look at other AMC heavyweight bikes as well. I would start looking at 1959--1961 model years.

It seems the factory stamping may have been damaged - accidentally or deliberately. The code was always Mxxxxx L , where 'x' are numerals and 'L' is a production code letter indicating what kind of gear cluster and final drive sprocket was fitted.

For 1962, your frame should be a duplex frame.

-Knut

It's been a long time since I have played with AMC Machinery my last being a '61 AJS 650 which I had to fit a Steel crank to after a failure, any way up to the early 60's the engine number started with the last 2 digits of the year followed by the model number in your case- year/G80/s/n, I think the frame number has its own series of numbers that with research should identify year also, if you have a mag the tag on it should have 3 or 4 digits on it identifying month and year of manufacture, I have found Roy Bacons series of books very informative and of immense help.

I have Bacon's Matchless and Norton books but I did go through the books and didn't find anything to help me. I have some spare AMC trans laying around however if this a 62 dated trans I don't have any AMC trans that old probably starting around 1964. I could be all wet here but I seen to remember the AMC trans on my 66 Mat CSR and the P-11 had those letters included in the serial Number its been quite awhile since I 've messed with those Trans I'll have to go up in the barn and check them out. I went out and got the Trans # off my 64 Mat CS and this # would be M 5392 G, thanks all for the info.

Mark