Author Topic: Curious Mark frame number - any ideas?  (Read 8792 times)

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Offline maverick65

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Curious Mark frame number - any ideas?
« on: 16 Jul 2006 at 15:14 »

I have just started to restore what I have thought for the past 50 years was a Mark 1 - I know I bought it as a Mk1 in 1957,  , but during the sixties pretty well any Douggie was worth a fiver for scrap, and so I may have swopped a few bits around subsequently. The original Log Book I got with it 1957 puts the original date of registration as 31st August 1948, and the frame number as 'T35/S/1572'

BUT it aint! Getting down to bare metal, I've just discovered the frame number is actually 35/1572. That's right - no initial T and no /S/ in the middle! There is, however, a 'P' in the same stamp format immediately under the rest of the number. There are no toolbox mounting stays under the top frame tubes, and the rear sub-frame lower mount is at the bottom of the frame, not on Mk1 'ear lugs'. So it should be a Mk4 or 5 - but that number just does not fit.

I know I should know the answer to this if anyone does - but I'm stumped! Here are a couple of images - can anyone help, before I do something dramatic that I know I'll regret later?


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« Last Edit: 17 Jul 2006 at 02:15 by alwyn »
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Offline trevorp

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Re: Curious Mark frame number - any ideas?
« Reply #1 on: 20 Jul 2006 at 05:17 »
maybe by the same company that built these
Hpn frame off a mk3

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« Last Edit: 21 Jul 2006 at 06:20 by alwyn »

Offline Doug

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Re: Curious Mark frame number - any ideas?
« Reply #2 on: 21 Jul 2006 at 04:20 »
I would think 35/1572 is simply a later replacement frame supplied by the factory. The HPN prefixes are speculated to also be replacement frames, but that does not mean all replacement frames had that prefix, or when they might have initiated (or stopped) that practice. The fact that the character fonts match the typical Douglas serial number stamps I think lends credence this was a Mark 1 returned to the factory for a legitimate frame replacement, and the factory stamped it with its original number. I have no idea if there was a legal requirement to note this in the old log books, or if anyone bothered to comply if there was!

So why did they not stamp the full prefix? Who knows. Perhaps they had worn out or lost the 'T' and 'S' stamp. Perhaps they did not feel it necessary; the numbers being the key element of unique identification. Also too, they eventually stopped the practice of stamping ANY prefix on the regular production numbering at some point during the Mark 3 run.

The frame does have the features of a later frame. Besides the anchorage for the rear subframe down low on the gusset as pointed out, it also has the rear frame lug terminating square to the vertical tube, rather than scarfed on an angle like the (early) Mark 3. The headstock lug is also the heavy, square lump at the petrol tank mounting rather than the slim round boss seen on the earlier bikes.