Re: Wiring Diagram for R-6 Overdrive

Posted by DavidPackard on 2021/5/15 13:34:26
Ernie & Howard

I was looking at the wiring diagrams, and found the same artwork in a prewar Motor’s Auto Repair Manual. I also remembered that Tinman was talking about OD electrical parts for his car, so I pulled up the website that he mentioned. If my interpretation of this information is correct the R-6 solenoid is powered to electrically ‘get-out’ or ‘stay-out’ of OD . . . . Is this correct ????????

If true that would make the logic of the reverse and kickdown switches unique to the early overdrive units. It will certainly alter the parts needed if a non-OEM system is put together. Also if this information is correct the R-6 OD should work without any wiring connected. It would not have reverse protection (that’s not good), or a kickdown function (you really don’t need a passing gear), but it will shift into OD. I haven’t found information about a lock-out cable, but how else would you sell a car in San Francisco without a means to lock-out the ‘free-wheeling’ function. My Motor’s manual doesn’t talk about any differences between six or eight cylinder OD units.
Here’s the info I found:

Borg Warner R10-R11 Overdrive Solenoid Reducer 12Volts to 6 volts (

I know the product is for a 6 to 12 V conversion but part way down the product description is the following;

Note Regarding R6 and R7 Overdrives.
The R7 installed in Chryser/Desoto/Nash/Hudson/Packard cars is a semi-electric type OD where the upshift is entirely done by centrifugal governor inside the OD. The only thing the Solenoid is used for is kickdown while still above the OD threshold of 25-35 MPH, means there is only power to the solenoid during kickdown function.
Without the solenoid connected, the car should operate as the 1st generation OD’s from 1934 did – they had no kickdown function.
R6 was mostly used in 1939, and R7 mostly in 1940 & 1941. Between marques, there are different setups.

The website text continues with instructions for wiring the older designs, but let’s go back to the Motor’s manual. Here’s an excerpt that caught my eye, we’re in the paragraph about working on the 40-42 OD, “The new solenoid operates exactly opposite to that of the 1939, in that it pushes the pawl in when energized instead of out.”

This statement may only be information about the interchangeability of solenoids, not the wiring of same.


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