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Rear subframe question

I am building a WM20/21 up from a frame. (I know this is crazy, but I enjoy the journey...) I've collected most of the parts to get the frame onto wheels, but need to make some decisions about the build before I go further.

The front frame was produced in 1939. The factory ledger shows that the bike left the factory in May 1940 and that it was fitted with an M21 engine. The bike was part of a contract(C3655)for the War Department. However, I don't know where it was deployed.

My preferred option is to keep the bike close to 1940 specifications, where possible. (I like the earlier petrol tank and 8" headlight, and don't want the rear pannier rack.) Option 2 is to go for more of a 1940-45 mongrel, given that bikes were often refitted during service.

Here's my immediate dilemma. The rear subframe is, I think, later than the front. It has no desert side-stand lug, but does have rear footrest mounts. Therefore, I can either proceed with this subframe or think about changing it.

- Does anyone know if this subframe may have been fitted in 1940?
- If not, would all 1940 bikes with an M21 engine -presumably for fitting to a sidecar- have had the long sidestand?

I'm not a purist, but would welcome views from Rivet Counters, too.

Thanks for reading this far,



email (option):

Re: Rear subframe question

Hello Craig,

I have send you a PM.


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Re: Rear subframe question

Hi Craig, The condition of the frame would be of greater concern for me than the fact that is it correct for the year. The differences are not that big, the 1940 frames did not have the fieldstand lug either, the stand was just clamped on the tube.

These rearframes are not that strong so if yours is in good condition I would surely use it on an early project, you even have the benefit of the pillionrests....:+1: :+1:

Re: Rear subframe question

Michiel didn't those early frames (1940) have the short field stand lug brazed onto the frame....And no pillion foot rest lugs? Mine is like that? Ron


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Re: Rear subframe question

I think there could potentially be quite a number of different rear frames as there are several different options and multiple combinations.

Rear foot rest mounts
Braised on prop stand lug
Side kick stand mounts
Sidecar lug both sides (possibly only post war but export models existed pre war too?)
Sidecar lug left side
Sidecar lug left side undrilled

This machine from contract A9764 has an undrilled sidecar lug on the left, possibly both sides?, no prop stand lug, you can see the bolt on the other side of the frame tube which makes it a clamp on mount, and the lugs under the foot brake for the side kick stand.



email (option): robmiller11(a)

Re: Rear subframe question

Yes, that is what I meant, there are so many options....that is why I think it is better to have a good later one than a bad early one.

The 39/40 Dutch Army M21 had the rear footrests as virtually all the prewar civilian bikes so they are not 'off period'. [They missed the sharp points of the later frames to be accurate].

And Ron, the first frames indeed had no lug for the fieldstand, so your frame must be a little later, more a 41 configuration. :slightly_smiling_face:

BTW, another difference between the early and later rearframes is the base material of the tubes, quite a few of the early frames, or maybe all, except the sidecarframes, had the thin walled high tensile Reynolds tubes and are very though, the later ones had thicker walls but a much softer material and will bend much easier if needed to get them straight. But no idea which frame is stronger in use....:slightly_smiling_face:

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