Packard Forum Index » V-8 (1955-56)

Thanks to all for the welcome. I feel like I'm amoung friends. To Pack120c, yes the 53 is the maroon one we drove to Galena last summer, hope to see you this summer at one of the POC events, maybe I'll have the 55 driveable by then. Regarding the T/L problem with the 400, I've ruled out fuses, but since I have no brake lites, I'm going to replace the stop light switch and rule that out as a cause for the brake light and T/L problem.

Based on my own experiences, if your T/L was working normally before and stopped coincidental with the brake lights not working, I'd say about 99% chance it's the brake light switch.

Quote:
If you discover that it's not the b/l switch, check the BTV. When I received my 56 Exec, I noticed that my TL was inop and my brake lights didn't work either.

Shortly after replacing the bl switch (with the '70's VW switch) and the brake lights still didn't work, my BTV went out. I guess because of insufficient fluid pressure to operate the switch. I followed Craig's plans and replaced my BTV with a modern brake booster and master cylinder. It was because I didn't trust the BTV.

That was just the start of my Packard adventures, as I soon discovered that not all mechanics are to be trusted and will bypass limit switches and install their own TL manual switches. The result was a TL disaster that has since been corrected. That was with the fantastic help of everyone on this website

Is there a way to test the stop light switch without it being on the car?

Was there a tester of sorts, "back in the day"?

Is there a way to test the stop light switch without it being on the car?

Was there a tester of sorts, "back in the day"?

I have known mechanics to use air pressure but it takes a fair amount -- around 100 psi or so to start. Kind of depends on the switch brand and sensitivity--some more, some less.

Welcome to the website. I am a fellow 1955 Packard 400 owner as of tomorrow! You can see her on the registry!

Esquireman

HH,
Is 100 psi what the pressure in the system on the car? Would the pressure be the same for all brake systems?


Found this so far;

forums.aaca.org/f120/how-test-brake-light-switch-272014.html

Not the same on all systems and conditions. 100psi would be an amount to make most switches turn on -- 50-75 might even do it on some sensitive ones. Pressures in the brake systems the switches are subject to vary by type unit, pedal ratio and pressure applied so not a constant. Range can be 100 to 1000psi or more.

As an example, I did some measurements during my brake project. A BTV with 1:1 ratio, a relatively small ram into an enclosed space (but not a piston) with 100psi applied to the pedal and no vacuum has 200 out to lines. Same 100 applied but with 20" vacuum assist and pressure out went to 800. Right off, I know mine will be less in real life conditions since it very much depends on vacuum available and my Packard has less than 20:.

Standard systems with around a 6:1 ratio should be somewhat in line with BTV numbers.

The aftermarket unit I'm playing with has less pressure than a BTV right out of the box. Because it has a 1" diameter piston in a cylinder pushing fluid instead of a narrow ram forcing into a confined fluid filled space and displacing the fluid, it is very dependent on pedal ratio for the output.

Phil,
for including your '53 Patrician Touring Sedan in the Registry.