P11A? Frame with number outside of the expected range

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Following your advice, I've cleared off more paint and found more numbers. Not what I was expecting though.
I have never seen any stamping in this area before. You have a '12' there, '1' appears to be less serif - maybe it's there, just not that clear, '2' appears to have the same font as your bogus stamping higher up on the headstock. My guess is the villains used this area as testing ground and later camouflaged the trial stampings.
To back up this assertion, there is no reason why there should be sifbronze on this part of the headstock. Usually there is some spill within 10mm of a joint.
Unfortunately the villains have ground off quite a bit of metal where the frame number should be.

-Knut
 
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These stampings with the SiBronze in the them are tiny. Not the same stamps.

Also, I used a straight edge to find out where material had been removed for the frame number and there are no irregularities.

Further, I stripped paint from my 1960 G9 and found numbers in the same area as these little numbers. They began with M12 and then a longer series of numbers. There is also some kind of a logo in an oval. So, they are all there from the factory. (except the P11 Frame number, which must have been added)

I wonder if my P11 frame was an unnumbered replacement frame and someone just stamped it to make it work with their loose Commando motor.
 
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This is quite interesting! I have a BSA A7 Special Racing Twin with stamps that are not super deep. Also have a A50 from the competition department that was given to a sidecar racer in '68 and those stamps were driven home pretty hard. I never thought about the life of the stamper. My job seems less repetitive now.
No doubt he stamps them deeper depend ing if it is a Monday morning or a Friday afternoon.
 
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I wonder if my P11 frame was an unnumbered replacement frame and someone just stamped it to make it work with their loose Commando motor.
Yes potentially, but where is the documentation to back it up. Without that a future prospective owner has to assume the worst when considering the value. Whilst you have it and enjoy riding it then this does not matter so depends on what your long term plans are.
 
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I wonder if my P11 frame was an unnumbered replacement frame and someone just stamped it to make it work with their loose Commando motor.
It was difficult to assess size of these "new" stampings. I don't think they were provided by AMC - possibly by the foundry casting the "malleable lugs", as AMC called them. I know the engine lugs for G12/G15 frames were cast by an outside company and given part numbers by them, I guess that's true for all the lugs used on these frames.
What a puzzle to prepare the lugs and assemble it all with the corresponding tubes!

As for the hypothesis of a replacement frame - if the original frame broke, it seems unlikely the engine broke at the same time. If it broke, wouldn't it be more likely to restamp a new set of crankcases and a replacement frame while spare parts were available, using the genuine number? If the engine didn't break, even more so!

Did AMC / N-V provide replacement frames at all? I have seen loose rear loops (from the Berliner Bros. warehouse, actually), but never a front frame / "diamond". I believe there were some restrictions on the sale and registration of chassis replacements even in the 60's, otherwise anyone could grab an existing frame number and have a "duplicate" bike registered. P11 production ceased in Nov. 1968, and I doubt there were any "loose" frames available (if at all) following the demolition of the AMC factory and warehouse in the autumn of 1969. Of course, it is possible that a spare part frame came from the Berliner Bros. sometimes in the 70's.

Have you tried to backtrace your frame's history by talking to the previous owners? It might be an interesting exercise.

-Knut
 
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Funny you should mention the previous owner. I just got a lead on who that might be. Unfortunately, he moved 4800 km east of me and has an unlisted number. So now I'm hunting for some old friends of his who may have contact info.

I have also never seen a spare frame. A few not-stamped engine cases but no frames.
 
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I have a Late G15CS and a Ranger. Both are stamped the same way on both the engine and frame - the 1 looks like this 1 in this font. I think this frame was stamped to match a '68 Commando engine, for which a PO probably had a title.

Commando motor would fit in a P11 frame, but wouldn't be balanced for rigid mount. Transmission and primary would need to be Matchless items, too - lugs on a Norton tranny are different than the P11 and G15. Also the engine is shimmed to the timing side and the tranny to the drive side to align the drive chain with the rear wheel. Both hybrid frames were designed for AMC motors, so shimming was needed to get the sprockets all in line.

Also, because the Ranger was built after the '68 Commando, Rangers have Commando head castings - except the side oil holes for rocker lubrication are not drilled and tapped. The oiling is still done, Atlas style, on the top of the head.
 
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