When Turner introduced the 1937 range there were two frame variants. The TL prefixed for the 250 and 350 ohv and 350, 500 sv variants, the TH prefixed were used for the 600 sv and 500 ohv variants. If you are looking for more detailed information on the heavyweight TH prefixed frames please visit Rob Stockdale’s, well documented, rigid frame Triumph website via our link page.
Throughout the years there are slight changes made on the location of the frame numbers.
From pre-war the frame number was stamped around the top rim of the headstock, and often repeated on the lug under the saddle. But from mid-1940 onwards, somewhere between frame numbers TL 19354 and TL 19652 it was moved to the left hand side of the headstock
Picture 2, saddle tube frame number pre mid 1940
The frame number on the top ridge of the headstock moved to the left hand side of the headstock. Second alteration is the exchange of the frame number on the saddle tube with a T.E.C. xx.xx letter and number combination. The abbreviation T.E.C. stands for Triumph Engineering Company then the month, eg one or two digits followed by the year in two digits, see picture 3 and 4. This set up would remain until the end of the 3HW production era.