Frame and engine numbers before the war were not matching as became the practice post-war.

Each engine number is unique, that is to say one numbering sequence ran through all models. In other words, engine number 10778 might be a 5T, 10779 might be a 6S. In this way engine numbers progressed at a faster rate than frame numbers as lightweight models used a different frame but were included in the engine numbering sequence. The engine number is always preceded by the year & model code so an 8-5T prefix denotes a 1938 5T. A 'C' suffix to the engine number denotes combination (sidecar), indicating a lower geared drive sprocket fitted.

As a general rule, when it comes to dating, four digit engine numbers (excluding the prefix) run from 1937 to early 1938. Five digit engine numbers beginning with a 1 then ran until mid '39 until numbers beginning with a 2 started in mid '39. The sequence may have reached a 5 digit number beginning with a 3 in 1940. This is only a rough guide as the numbering sequence is not strictly chronological as manufacture and sales proceeded at different rates. However, over the three-year period it generally follows this sequence

Only one type of frame was used for the heavyweight range in 1937/38 and it is prefixed with the letters TH. The earliest TH frame number I have recorded is TH 130, a 6S from 1937. It seems likely that it started with TH 101 according to later practice. As a general rule 3 digit, and 4 digit frame numbers beginning with a 1 are 1937. Frame numbers beginning with 2 - 6 are 1938 and numbers beginning with a 7,8 or 9 are 1939. TH frame numbers did run into 5 digits at the end of 1939.

In 1939 a new frame was introduced for the T100 with a TF prefix to differentiate it. The number sequence started from the beginning again. The earliest I have recorded is TF 190 so it seems likely that it started with TF101. As with the other engines the T100 used the same prefix (e.g. 9T100 for a 1939 Tiger 100) but continued the previous engine numbering sequence so T100 engines started with a 5 digit engine number. The new frame coincided with the advent of the 4 gallon tank with knee-grip recesses (continued after the war) and the two tanks are not really interchangeable as fitting the 4 gallon tank to a TH frame will result in the forks hitting the tank on full lock. This is due to design changes around the steering head. The headstock was mounted at a steeper angle and the forks used a shorter lower link to reduce the trail.

The TH frame used 105mm (between centres) lower links on the girder fork whereas the TF frame lower links were 100mm. The effect of fitting the longer (TH) lower link to a TF frame is to produce an alarming high speed wobble. In addition, the TF girder used a different top crown (also referred to as ‘head clip’ in the parts book). The T100 top crown/head clip had a deeper cast lug for the spring top retaining bolt making it stronger. Quite possibly it also had other more subtle differences so should not really be substituted by the TH version. Apart from this, the girder fork remained the same until 1940 when check springs were added. Again, the lower link changed as it now incorporated a lug for the spring. This mod also necessitated a different headlamp mounting strut arrangement. For the 1940 season the TF frame was applied to all models.

Frame numbers are stamped horizontally at the top of the headstock and again across the back of the saddle tube. The front frame half is most easily identified by the absence of the crease in the front down-tube for the dynamo on post-war models. The rear frame half should only have sidecar lugs on the drive-side making it easily identifiable from a post-war rear frame which has sidecar lugs on both sides. The front petrol tank mounting bracket was constructed from flat steel pressings welded together up to 1938 but for 1939 was modified to a one-piece casting. The odd blank lug underneath was drilled on the singles to provide a cable stop for the valve lifter cable. On the singles the head steady arrangement was bolted to the rear petrol tank mounting bracket using the double ended stud F946 used to fix the rear mudguard stays to frame

Note: The four domed bolts that hold the handlebar top clamps are 5/16'' bsf, 22tpi, not the regular 26tpi.

Unfortunately there are no factory records for pre-war production as on the 14th October 1940 the Luftwaffe destroyed the factory. This, together with the non-matching numbers makes dating difficult. I have been compiling a database for many years based mainly on original log books and am now able to provide an approximate dating service or indicate whether engines & frames now together are indeed a matching set. Owners in possession of a machine with the original date of first registration are invited to contribute the information to help this valuable resource. I am particularly interested in hearing from owners who think they may have Tiger 100s dating from the 1941 season as it appears there may have been some such machines exported to Canada.