There is a pad, P/N T-1906 that is used between the CC arm and the frame. Bruce's book says it was used in 1919-1921 on the trucks, but a very knowledgeable friend tells me it is leather, and was used on the early cars. Bruce's book says it was woven cotton, possibly scrap top material?
I cut a rectangle piece of rubber for this use - probably 3/16” thick. It’s surprising how much it cuts down vibration.
Ones I’ve seen on TT’s that look original resemble band lining material.
That must be a factory number, as TT part numbers in my parts book all start with 10 or 11 and car part numbers begin at 2500.
The Rodda 1909 book makes no mention of the pad, although it does highlight the unique, rounded over shape of the upper part of the early crankcase arm.
Not to hijack the thread, but to add to it:
This pad, whatever it's made of, is insulating the engine from the frame, making it harder for the battery's (-) power to reach the starter. It's just that much more reason to place a cable between the engine and the frame.
The front pan motor mount (bearing) to the front crossmember provides plenty of grounding for battery voltage to reach the starter when the 2 rear mounts are on rubber...
Factory numbers from Bruce's C-D encyclopedia
Fac. No. T-1906 1919-20 Starter field coil end cambric insulator. .010" thick
Fac. No. TT-1906 1918-19 Crankcase arm pad. Cotton webbing
Seems the pad is only a TT part.
And... The TT crankcase arm was fastened with the bolt coming up thru the framerail, cotton webbing, and crankcase arm, then a spring (similar to the wishbone ball cap spring), then the nut & cotter pin. Wood blocks and the bolts thru the sides of the crankcase arms were not used in TT’s except at the very beginning of production.
Just for useless information the 1923 Nash was the first car to use rubber motor mounts.