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'63 manual trans back-up light switch - rehab?


BillyBob
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I recently replaced my 3-speed back-up light with NOS -- lights now work. I tested the removed switch for resistance (ohms). They were very low as compared to NOS. I suspect internal contacts are dirty. What experience is there in rebuilding/rehabbing old switch? Thanks, Bill

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  • 2 weeks later...

I recently had experience with the Starter Cut Out Switch (SCOS) with my powershift AT. In fixing that I noticed that this switch is similar to the back-up light swtitch. In fact, I think Studebaker International supplies to same part to replace both. All of this is a long way around to say that I suspect your manual transmission back-up light switch may be similar or interchangeable with the switches I was working with.

The first thing I noticed and address was that the electrical connectors were very dirty and corroded, so I thoroughly cleaned both the mail and the female parts.

But there were more problems, and I did replace my SCOS. But I never throw an old part away unless it is painfully obvious that it cannot be fixed. So I decided to see if there was any chance the old switch could be rescued and I decided to open it up. First I had to tear off what appears to be rubber silicone sealant the covers the terminals. When I did that, the first problem was obvious. One of the wires soldered to the terminals was hanging by only two strands of wire. But still I was convinced there was something wrong with the switch internally, so I pried up the 3 metal tabs that hold the Bakelite top in place, pried out the Bakelite top, being careful not to allow any parts to fly out and get lost as I pried it apart and making notes of how the two internal components were assembled and needed to fo back together. Once inside, everything was a little dirty, but otherwise perfectly normal. I cleaned the parts even though I do not think that was the problem. However the bellcrank on the switch could be moved with only the greatest effort. So I soaked it in a solution of AT fluid and acetone for two weeks, and when that did not make a significant difference, I switched to WD-40, but with no significant improvement. I finally realized that the reason why the bellcrank was frozen up was that there was a buildup of rust between the surface of the bellcrank and small disc between the bellcrank and the SCOS mounting arm (the flat piece of metal attached to the bottom of the SCOS). From that point on it was pretty simple—all I had to do scrape out that rust with thin blades of various sorts. That freed up the movement of the bellcrank and hence of the SCOS. After cleaning everything up, I soldered two new 14 gauge wires to the terminals on the top of the Bakelite cover (the old ones were both brittle with the insulation cracked and coming off), connected them to the male electrical connector, and reassembled the switch. (Actually, the connectors are mixed gender, depending on how you look at them—if you do not get the humor, I apologize.) Then, I covered the Bakelite cover with a protecting layer of silicone rubber cement.

What did I learn from all of this? The starter cut out switch has three week points—the wiring harness connectors are prone to corrosion, the wires are prone to breaking at the point where they are soldered to the terminals in the Bakelite cover to the switch, and rust buildup between the bellcrank arm and the disc attached to the mounting arm can freeze of the switch so it is inoperable. Fix all three of these things and the SCOS will be almost as good as new without disassembling it as I did.

I suspect that what I learned will also apply to your back-up light switch.

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Thanks - quite a story! Yes, curiosity got the better of me and I, too, disassembled the switch. Mine was sealed with tar-like material. What a mess! Wires had good connections and bellcrank moved freely. One terminal inside the bakelite cover has some kind of discoloration - does not look like corrosion. Inside was clean and filled with oily-like substance. One day when I've lots of spare time, will clean terminals, attach new gender-appropriate connectors to new wires and solder to switch connectors. Will probably use liberal amount of dielectric grease on reassembly. ...and make trial installation on car. I attempted to take ohm measurements on old and new switches and really couldn't make much sense of what I measured other than new switch had consistently higher readings.

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