The Stovebolt Site Forums The Shop Area General Truck Talk Stop light switch location on a 39 1/2 ton

I have a question for anyone that might be able to help. After searching the site I cant seam to find where the stop light switch should go on my 39 1/2 ton. Getting close to putting it on the road but i think i should have brake lights lol. anyone have some info or a picture of the location and how its mounted?

thanks
matt

Did your 39 ever have stop lights and signals ? I would plumb a pressure switch into the brake line from the master cyl.Wire it with fused power in and the other lead to your stop lights.If you have a signal switch (like a Signal Stat/Napa 900),one lead on the switch is set up for stop lamps.Signal lamps in the rear and stop lamps are the same.

Fatboy0169, I just looked it up for you.The Black/Grey wire on the Signal Stat model 900 and 905 is for your stop light switch.

i doubt it had signals but would all cars have break lights?

i bought a brake light switch from jim carter that is supposd to go on the toe board.. im just not sure where

It's on the master cylinder, goes on the side.

Here's American Classic's pic of a master cylinder

I can send you a shot of mine if you need it.

Now that I look at Jim Carter's you must have got the mechanical type. You can put it put it anywhere that makes sense. You're going to have to rig it just right so it hits at the right time. I'd recommend you just get the hydraulic as it's a breeze to install

fatboy0169 -
If you are interested in installing the correct light switch like the original one, than it will mount on the master cylinder as InMy40s states. Your master cylinder looks like the one in his picture, that he has posted for you, and it screws into the 1/8" pipe thread hole where the small brass plug appears at the back of the master cylinder on the left side (as it is mounted). That is the correct way and the way it came from the factory. You run a hot wire to one side of the switch and from the other terminal, you run a wire to the brake light. When you step on the brake, the pressure increases inside the master cylinder, to stop the vehicle, and the pressure also activates the switch. This called a brake pressure switch and it is still available from most neighborhood auto supply stores. It was used on all of the cars and trucks up ito the 40's, some into the 50's.
Again, it is a 1/8" pipe thread brake pressure switch.

Joe

thanks i guess i ll return the mechanical and get the pressure type lol...just want to thank all the guys on here for the help im sure i will get needing... thanks again

OR, you can just rip out all that stock stuff, and install an underdash pedal hanger, with the master cylinder outside the firewall!!

then you can use the mechanical switch.

Now if you were to look at a master parts book you guys could see that both are correct a mechanical switch is screwed to the toe board but they could have a hydraulic switch (common on most smaller trucks)
Mike

I have a '56 Chevy truck type mechanical lever switch screwed to the bottom of the toe board under the brake pedal arm instead of the hydraulic pressure switch. It's been good for over a decade.

Sorry. That's in my 40 GMC that's in the gallery under John Shipman.