I bought this old MOPAR overdrive transmission yesterday from a CL ad. It seems to be a simple version of the OD's used in Airflows in the early 1930's. The seller said it was from a '36 Plymouth, and my Plymouth Master Parts catalogue lists it for 1936 only. It appears to be in really good shape internally, but when I move the lever on the side of the case to thee rear, it only engages free wheeling - no overdrive. I can see two pawls through the inspection hole on top, and they appear to move out under some amount of centrifugal force and lock the planetary. Has anyone here had experience with one of these transmissions, or know how it is supposed to operate. It seems to be all mechanical - no governor or solenoid, nothing electrical. I'd like to use it in my '36 coupe if it 's worth the effort.
That is probably what it is ,free wheeling option no OD. Free wheeling was a fairly popular deal in the 30s ,lift off the gas and no engine braking.
I had one of these from a DeSoto Airflow of about 1935 in my '51 Plymouth against a 262 Chrysler 6. It was an overdrive but also had freewheeling til you stepped on the gas. This setup gave me 6 forward speeds but second OD and straight high were the same ratio. It was fun to run top end against someone on the highway (rural AZ) in second OD and shift to high as I went by. This was all in the '50s.
The Jalopy Journal
