identifying a douglas - mk3 (HPN frame prefix)

[trevorp]

Reg may be able to help with this i have a friend with a douglas unrestored the frame number is hpn and the engine number appears to be a 4 digit number starting with a 6 it has then been overstamped with a t35s2*** it appears to be a mk3 and is built like a sports although it really is a bitsa

[Reg]

Reg may be able to help with this i have a friend with a douglas unrestored the frame number is hpn and the engine number appears to be a 4 digit number starting with a 6 it has then been overstamped with a t35s2*** it appears to be a mk3 and is built like a sports although it really is a bitsa

The prefix letters HPN appear to have been introduced firstly on the later Mark 3 models of 1949 and then used on the Mark 4 series which began with machine number 7000 introduced in November 1949. These prefix letters however were not found stamped on all frames from this series. There is also no indication whatsoever as to what HPN actually stood for. Your friend's Douglas may well have been a late Mark 3 as the engine number beginning with 6 indicates a machine of this series. Why it has been overstamped with a number configuration indicating a T35 (Mark 1) I have no idea. Maybe to satisfy vehicle taxation authorities? 

Reg.

[trevorp]

Thanks reg much appreciated

[pryfield]

I have a couple of Douglas frames with  HPN as the only identifiable marking. Twenty odd years ago, a fellow who had purchased a MKIV brand new , told me that quite a number of frames were replaced under warranty due to frame breakage in the early fifties. He was of the opinion that frames with the HPN number were replacement frames. I  have no idea if this is actually correct but its certainly plausable..Nev

[Doug]

I was just looking through some NCR back-issues dating from 1976, and came across a letter from Eric Brockway replying to a query about the HPN frame prefixes. In the Oct/Nov issue, he states the prefix refered to Heat-treatment Pickle Normalized. It seems strange that they would make a special note of a production process in the frame number. But the late Eric Brockway was Managing Director for Douglas Sales and Service, so would have been in the position to know. As previously mentioned, they were issued as warrenty replacment frames.

-Doug

[trevorp]

well we are all a bit smarter now thanks all

[Daren W Australia]

Hi all I have just bought 2 new frames one is an unused replacement frame no numbers and the other is a Mk5 style frame with a frame number T35/S/890 stamped on it also has the engine and gearbox fitted with the same numbers the rear subframe has been stretched on 890 to combine mk frame and T35 subframe pics to follow Regards Daren

[Daren W Australia]

Hi the number for the blue mk5 style frame is actually T/35/S 883 and you can just see the HPN stamp on the unused frame Regards Daren

[rpf94]

 in the 1970s i helped clear out CLAUD RYE'S (FULHAM DOUGLAS MAIN DEALER) celler of all his motorcycle spares as he was changing his business to bearings,
among the new parts removed were a number of mark series frames all brand new and all had HPN stamped on them.
hope that is of interest.