Re: Brake Light Switch, 1937 120

Posted by Don Shields On 2023/10/27 22:49:39

This has been my experience with DOT 5 fluid and brake light switches:
I converted a 1937 120C to DOT 5 fluid in the late 1970's, never had a problem with it. I sold that car in 2003;
I switched my 1933 Packard 1002 that had been converted to a hydraulic braking system, probably around 1940, to DOT 5 fluid in the mid-1990's, have yet to experience a problem with that brake light switch;
I converted my 1954 Convertible, bought in 2005, to DOT 5 fluid around 2008 and did experience a switch failure within a couple of years. The fluid leaked through the switch and shorted it out. I bought 2 switches at that time, have yet to need the second switch.
To me, the benefits of DOT 5 fluid far outweigh the potential detriments in shortened switch life. It is also helpful that these switches are easy to replace, inexpensive and readily available.