Wierd Gearbox Number

maximini · Oct 7, 2010

I picked up a used gearbox off a 750 at a swap meet this week and when I cleaned away some of the crud on it I noticed that it has a strange id number stamped on it. The fourth digit is tough to make out as there is a small nick in the case.

The number is 126810 Y (i think the fourth digit is an 8 but not sure. What I can't figure out is what the Y is. I've never seen a Y after the number. Anyone have any idea what this might be?

BillT · Oct 11, 2010

I believe the letter after the serial number indicates some running change in the gearbox. The one on my Ranger has an 'S' after the number, and the NOC thinks it may signify a change in the 4th gear.

Perhaps this is what the 'Y' means - a modification to one of the gears or bearings?

Marathon Man · Oct 11, 2010

FWIW, I've got a 'K' stamped in my case about an inch to the right of the serial number.

maximini · Oct 11, 2010

This appears to have been stamped at the same time as the identification number as the stamp size and style are identical. Also, the 'Y' is right after the number. I asked an older gent who was a mechanic at a New York Norton dealer in the 1970's and he said that he thought that they stamped the 'Y' to indicate that it was a warranty replacement. He said that sometimes they stamped them and sometimes they did not bother. Has anyone heard of this?

pelican · Oct 11, 2010

Don't know? Maybe it is a qc or lot indicator. I have a T stamped on my rh4 head.

rwalker28 · Nov 2, 2012

I picked up a used gearbox shell 1481XX (not really XX, those are X's are so I don't print the whole number, I am paranoid,) serial number stamped way to the left (so 1971) and an L stamped way to the Xright an inch (2.54cm) or so from the edge.

MFB · Nov 2, 2012

My 70 model has its gearbox number way to the left, and the letter M way to the right, only 5mm from the edge.

mechanic matt · Nov 3, 2012

This is very interesting. My 1973 850 has a "C" stamped after the serial number. I raised the question on this forum but never received an answer. I thought it might stand for close ratio or competition, but all the gears had the standard number of teeth. I guess it really means nothing.

Wierd Gearbox Number

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