Triumph's Dating Codes
The following comes from my many years of research into the old Triumph Works at Coventry, not from any documentation, for none survived from the air raid attack on the night of November 14th 1940.
From the time when Triumph started producing machines with their own
engines for 1905 the engine would be date stamped with the date of
machine assembly. Engines, frames, and later, gearboxes were made in
different parts of the Works. The frames and gearboxes
were stamped with a sequential number which identified their type,
while engines were assembled but un-numbered.
From their different shops (workshops) the engines, frames and gearboxes, along with other items, were transferred to a central stores from where they would be collected as 'kits of parts' for putting together in the Assembly Shop. As the storeman would not issue items in direct numerical sequence, and subsequently move the following items along the shelf, there was no direct correlation between numbers at any particular time. Very often the most recent items received would be placed on the closest shelves or hangers, and it would be the closest items which would be selected when the apprentice lad with his barrow turned up for the collection of more 'kits' for the assembly shop. So often an earlier frame or gearbox number might appear with a later numbered engine; and occasionally a very early number could appear with a much later engine, simply because it had languished down the far end of the stores.
Triumph identification of the assembly sequence of each model came
from the engine number, for this was stamped on completion of the
Initially the engine number was followed with the stamping of the
actual day, month and year; for example 13-8-10. (The 13th of August,
As production increased the actual date was replaced by a two letter code indicating simply the month and year. This was in accordance with the code TRIUMPH CODEY, whereby T=1, R=2 through to Y=12.
(The code was not TRIUMPH CODEX, as well circulated in books and internet Web pages! This has caused much confusion amongst owners of veteran Triumphs who will never have seen an X on their bikes, but may have seen the Y.)
The two-letter code was first used in September 1910, where that month was coded as OD (9,10)and the 1910 code proceeded through to December as YD (12,10).
The code was fine as two letters until 1913 was encountered.
The code then became three letters and January 1913 became
TTI (1,13) YTI (12,13) was December 1913.
1920 became a problem as there was no letter for 'zero'. So, while Y remained as 12, an ‘X’ was introduced as a ‘zero’. Hence the confusion over the code as mentioned above. January 1920 was indicated by TRX (1,20). Y and X appeared together in December 1920 as YRX (12,20).
This three-letter TRIUMPH CODEYX code ran until, and including,
(Apart from the Model LW/Junior/Baby which continued with it.)
Thereafter further letters appeared in the stamping, which were not within the letters of the code. The much respected late Bob Currie told me that no one had made sense of the new code, while another said that the letters didn't mean anything. I reasoned that no one picked up a punch and hit it with a hammer without a purpose - well, not a rational person, anyway, and again I reasoned that Triumph employees were pretty rational people or they would not have been hired.
Having purchased the remains of two Triumphs with such undeciphered letters I decided to find out for myself what they might mean. So I started collecting Triumph engine numbers and letters from surviving machines. (It used to be Great Western Railway locomotive engine numbers in my younger days). I had been told that the three P&M engine assemblers stamped an initial with the engine number, probably for warrantee purposes. But did ALL Triumph machine assemblers have three initials? Most unlikely.
To avoid making the task too difficult I concentrated initially on Models P, and then progressed to other models. I discovered that the reason why no one had broken 'the code', was because there was not a single code, as the pre-1924 had been, but a multitude of different codes. To prove my month and year findings I had to discover what changes there might have been between, say, between my theoretical February 1925 Model P and a theoretical August 1925 model. Thus began my researches into model variations, and although never intended I ended up learning so much that I became a VMCC Triumph specialist!
You'll not find these codes by reading on, for I have still not
worked out all months for all years. I am particularly short of
a few months of 1924, when the code first changed, and the early
1930's when sales, and thus survivors, were not made in great
quantities. Thus, I still need Triumph owners to come to me
with their numbers and letters. I'm pretty sure of the letters
which I am missing, but like my 'Facts' series of booklets I want
to be 100% SURE before I release the code information. (Someone
who shall remain nameless has used the dating information I had
given him over the years on his multitude of engines and published
on his Web page, but he has misinterpreted and added some incorrect
With my breaking of the codes I am able to approximate with reasonable accuracy how many of each model were assembled during each month, in an effort to replace the lost records of The Triumph Cycle Company Limited.
Note - In all cases the dates are that of machine assembly. The inaccurate, and deficient of some models, readily available lists claiming to give annual engine and frame numbers are MODEL years, not assembly years. My 1913 MODEL was assembled in December 1912, for example. Those lists appear to have originated from Triumph's Meriden Works during the Triumph Engineering Company days and thus can maybe excused for inaccuracies, although duplicate numbers in different years and the omission of some models I cannot excuse.