Packard Forum Index » Post-War (1946-54)

Well the new switch did the trick

Glad the problem was solved. You said the other switch was new. As has been mentioned before either this thread or on several others, if silicone brake fluid is or was used, the switches seem to have a very short life.

When I got the car the brakes were rusted solid so I rebuilt the wheel and master cylinders. Only used std
DOT brake fluid. Good heads up about the synthetics.
Thanks again
OTG

" if silicone brake fluid is or was used, the switches seem to have a very short life."

Good ppoint HH56. But that begs the question as to what is inside of the switch going bad due to the DOT5??? Is there something iside of the switch that does not exist in the rest of the brake system??? Some switch forensics needed here.

My Exec has had the DOT5 silcone brake fluid in it for over 12 years that i know of. Maybe longer. Original switch went bad and replaced about 12 years ago when i got the car. Replaced again about 3 years ago with mechanical switch due to brake conversion.

Bottom line: there must be somekind of material in the switches that do not exist anywhere else in the brake system. I got well over 20K miles and 12 years on mine.

I cut open the switches that went bad on my 400 where I use silicone fluid. The electrical contacts were burnt and corroded with carbon which inhibited the flow of current. This occurred on a Packard three terminal switch and also a two terminal switch that in addition to lighting the brake lights, turned off a normally closed relay that supplied current to the TL system. When cut open the failure was very noticeable. Either drops of silicone worked past the seal or some gaseous discharge of the silicone worked past the seal.
Installation of Howard's suggestion of a GM mechanical switch resolved the problem.