39 Stop Light Switch

[buick4547]

My stop light switch quits working every three years or so.  I install a new one and it works fine for a few years than stops working and then the cycle continues.   I think I once saw a post that stated that the failure had to do with the switch not compatible with modern brake fluids.  Is this true or did i just dream it? 

 

Thanks

[jenz38]

Thats sad..

I think the cheap china "quality" of all the switches are the problem..

try to get another brand also with another on/off range or connectors on it , Mainly the thread is the same.

My switch i have changed 5 years ago (Standard ) an it works fine with DOT 5 Silicone fluid.

Maybe you have too much power on the switch? thatd can be a reason too.

You have DOT 4in your lines ?

Dont do that, use DOT 3 because of the agressive additives in the DOT4.

[trp3141592]

Hi,

 

My experience with hydraulic stoplight switches in the 40 LaSalle was that replacing the switch was an annual event until I flushed out the silicone brake fluid and installed DOT 3 fluid.  I had gone so far as to install and idiot light in the dash to indicate that the brake light wires were energized.  I now use DOT 3 in all the cars, and the brakes get flushed every other year.  I have not replaced a swich since I started that practice.

 

The discussion of pro-silicone/anti-silicone rages on every year.  I suspect the questions over the Kennedy assassination, President Obama's birth certificate, and the home planet(s) of UFOs will be resolved before the brake fluid debate is ended.

 

--Tom

[buick4547]

Thanks to all for their reply.  Dot 3 and a good flushing it will be!

[DonMicheletti]

I have restored a couple of cars with hydraulic brakes (one my '38 Roadmaster). I replaced all rubber parts and stoplight switches and converted them to silicone fluid. The ;38 was done 25+ years ago and I have not had a bit of problems with the stoplight switch or anything else.

The switch failure being attributed to the silicone fluid (which is pretty innert) is surprising, especially since DOT 3 is such an aggressive paint stripper.

[packick]

A guy in our local Packard club had the same problem with his '58 with silicon brake fluid.  He switched back to Dot 3 and never had the problem again.