40's back up light switch

[gary griffin]

I need the correct mechanism that goes on the 3 speed standard shift transmission. I acquired one but found out later it is for an automatic transmission. Is there a diagram to make one, or does anybody know where I can get one. One of the last bits needed to complete my 1942-6719.

[Jay Friedman]

Gary,

I had the same problem with the back up light switch, bracket and rod to the shift lever with my '49 with a manual transmission.  Like you I had Hydra-matic parts, but with a friend's help I adapted them so that they work perfectly on my car.  (FYI: the manual transmission is the same in '42 and '49.)  We were helped by my parts manual which lists the different parts according to transmission type.

1. The switch itself is the same on automatic and manual transmissions (and also from 1940 to 1951).  The switch is constructed to take into account that on a Hydra-matic the transmission shift lever moves to a down position to engage reverse gear and on a manual transmission moves up to engage reverse.  As such, when the switch operating lever is in its middle position the switch is "off", but when it is either in its up position or its down position it is "on". 

2. The switch bracket which holds it to the transmission is also the same, except there is a part called a "support" which is used to adapt it to the back of the manual transmission.  However, since I didn't have a support (whatever it is), I merely used one of the holes in the bracket and bolted it to the back of the transmission using one of the existing bolts holding the transmission rear housing to the transmission main case.  It's it is in a horizontal position and is kept from moving up and down by being wedged against the rear housing.

3. There a difference between the rod from the switch operating lever to the transmission shift lever (the 1st-reverse lever on a manual trans) depending on transmission type.  The manual transmission rod is shorter and where it connects to the shift lever there is a part called a "spacer" to keep it from wobbling.  To adapt the Hydra-matic rod we bent it into a U shape to shorten it and added a washer to where it attached to the transmission shift lever to take the place of the spacer I didn't have.  You'll probably have to play with the rod by bending it to different angles before you get it right, but you can make it work.  The result won't be neat looking but who beside you is going to look under there in any case.

Hope this helps and let me know if you need more info,

Jay

[Barry M Wheeler #2189]

Gary, I don't believe that in 1942, they used an "automatic" back up light switch. I got the dash switch and brackets from lots of 1946 and 1947 Cadillacs. You should use a B-31 lamp and a movable (up and down) bracket with the "feathered" lens like the parking lamp lenses. I believe the lens with just "circles" on it are later than 1942. Contact Rob in Delaware and see how he fixed the lamp on his 1942 convertible. He has a different first name but his is the only '42 conv listed in the Directory in Delaware.

[Barry M Wheeler #2189]

Gary, I may have spoken too quickly. You might be interested to know that I was "thinking" about this either while I was half asleep or was dreaming it before I got up and got ready for church this morning. I realized that in 1942/47, the switch that I was removing was for fog lamps, not back up lamps. So, please disregard what I wrote, and keep on the path you and Jay were on. Good luck. BW.