MTFCA Forum

What is the original shaft diameter of the crank at the pulley? I understand that there were 2 sizes of cranks.
Thank you

1.248 IS STANDARD, Bob

Thank you Bob,
do you know if there were 2 sizes of cranks?

only one size I know of, Bob

The way I read the question is the diameter of the crank at the pulley, so 1.248 is not correct, that's the journal size. The gear presses
on to the shoulder of the front main journal so the pulley diameter of the crank shaft is smaller.

There may be a misunderstanding on the crankshaft front pulley area. The crankshaft diameter is the same all years. It is the pulley, at the fan belt diameter, that changed. The small pulley for the narrow nose pan but used in early wide nose pans into around 1919 and the large pulley for the wide nose pan but started use around 1919.

kmatt2 wrote: ↑

Mon Dec 14, 2020 3:19 pm

There may be a misunderstanding on the crankshaft front pulley area. The crankshaft diameter is the same all years. It is the pulley, at the fan belt diameter, that changed. The small pulley for the narrow nose pan but used in early wide nose pans into around 1919 and the large pulley for the wide nose pan but started use around 1919.

Yes, but the diameter of hole in the pulley did not change. Besides, the OP didn't ask about pulleys, he asked about the crankshaft diameter where the pulley goes.

I believe that Kerry is correct. The diameter in question would be less than the front main journal diameter.

Contrary to what has been said above, not all Model Ts used the same crankshaft.

The first 2500 Model T’s used a gear driven water pump and fan, so there was no pulley at the front of the crankshaft. Additionally, the starting crank ratchet on these cars was a different design, and the front of the crankshaft was machined smaller in diameter than the crankshafts used on post-2500 cars.

Respectfully submitted,

Trent Boggess

I just measured over a dozen - nothing in the '09 era but diamond web & AA & EE cranks are approx. 1.1855 in the pulley area.

Jerry, I did say that the crankshaft diameter at the pulley was the same for all years. I did not consider the early waterpump cars. The pulley at the fan belt information was given for general information to all readers, some of who are new to the Model T. Sometimes things get lost in word of mouth over the years.