Frame Number Location
This is the frame for my 1955 T20 Road Cub - T20 15185.
I'm often asked for the location of the frame numbers on Cubs and Terriers. I also get a lot of email asking I add a bike to the people page and the owner lists either F3389 or F4421 as the frame number. Those are not frame numbers - they are the part numbers for the headstocks that are welded to the frames - sometimes referred to as the part number of the completed frame. All frame part numbers start with the letter "F". All Cub serial numbers start with "T".
In many cases, it's pretty easy to tell they are not serial numbers by the fact they are clearly molded in numbers at the time they were poured - not stamped numbers. Serial numbers were always stamped in on the assembly line - both frame and engine at the same time - by the same person.
Looking at the picture above, you'll see that below the headstock number - in this case F3389 - you'll see the number T15185 as it's stamped into the headstock, just below the headstock part number. On this machine the serial numbers match and are represented as T15185 on the Frame and T20 15185 on the engine.
To further confuse the issue, Triumph started stamping in *some* headstock part numbers in 1958/9. The fortunate part of that is the ones that were stamped are all F4421's, so it's pretty easy to discount that as a serial number.
Lastly, it appears there are some frames that were never serial numbered. I have a 1961 Cub that I know to be correct from the factory as I know the original purchaser. There is no frame number stamped into the frame.
Now you know what you're looking for, go here to find out how old that Cub/Terrier is Serial Number Dating
Simple isn't it?