I'm slowly sorting through the rats nest under the dash. It's not AS bad as I thought, though there are going to be some challenges.

I found out that the problem with my stop lights is that there simply is NO SWITCH of any kind- Nothing on the pedal, nothing on the master cylinder... So, I decided to add a switch. I am going to use one that is mounted to a bracket and actuated by the pedal itself... I have seen some instructions on how to go about this, but I have a question-

Should the switch be Normally open or closed??

My initial thought, looking at the diagrams, is that it would be Normally OPEN, and CLOSED by depressing the brake pedal. I bought a switch for a '70 ford truck, and when I put it on my multimeter, I found that it is normally closed, and the circuit is opened when the plunger is pushed... Does anyone know if the pressure switch on the '66 was the same way?

-Andrew

 

The 70's switch is the one to use -- its "normally closed" but only in the sense that its spring loaded plunger closes the switch when the pedal is depressed.

You mount the switch somewhere such that when the pedal is up (no braking) the plunger is depressed and the switch is open. The orignal hydralic switch is N.O.

You can make a bracket that bolts or attaches to the steering column, which is what I did for a number of years.

Or, if you are adventureous, or have the dash appart anyhow, you can drill a hole in the top of the clutch/brake pedal assembly, locating the plunger switch strategically so that when the brake pedal is up, the plunger is depressed and the circuit is open. I did this when I redid the whole firewall and swapped to automatic tranny. You drill the hole and thread it to the same threads as the switch. Makes for easy fine adjustments.

In either circumstance, you want the brake lights to come on pretty much when you touch the brakes. That is the weakness of the hydraulic actuated brake light switch -- they come on later and your risk of being rear ended is higher. To get them new switch to close at the right time, you must build a bracket or mount it in a manner that allows for adjustment.

Good luck.

I don't have anywhere easy to host pics, but if you need them, lemme know and I can send you some....

 

Ok- that makes PERFECT sense now. I was thinking backwards- The switch should be depressed, and therefore the circuit OPEN, when the pedal/brakes are not being used... And the circuit CLOSES when it is depressed, releasing the plunger....

Pics would be great- AKGott (at) gmail (dot) com

Thanks!

-Andrew

 

1948/66, the brake light switch (C1AZ-13480-A) is pressure activated. It either threads directly into the front of the master cylinder, or into a brass fitting that threads into the master cylinder.

When Ford went to dual master cylinders in 1967, the brake light switch attached to the brake pedal.

The switch used in 1967, is 1967 only as is the brake pedal.
---------------------------------------------------------
D2TZ-13480-B .. Brake Light Switch (Motorcraft SW-691-A).

Applications: 1968/77 F100/350 (except 1975/77's with Speed Control).

1964/72 Ford truck parts catalog pic of the whole tamale for a 1969/72, look here: Illustration Section 75, Page 21.

 

Thanks, Bill.

Somewhere along the road, the original brake system (among other parts) was replaced with a dual master cylinder... Which is why I had to find an alternative to the pressure switch- Although I COULD probably find a way to rig a pressure switch, it seems that they cause problems, so I might as well change over to this way of doing it!

There is evidence of a prior attempt to do this already in place- a few holes drilled- but for whatever reason it was removed.

 

Before coming upon FTE did know any better so with the front disc brake upgrade I kept the pressure switch, purchased a T fitting and used a bottom tap with same dia. and thread count as the switch, then attached it to the brake proportion valve, been waiting for it to stop working and upgrade to electric switch, this was over 15yrs. ago and still waiting, don't find too many 'tailgaters'. Agree, go with the electric switch, much safer and modification probly less involved than going w/ pressure switch.

 

There is another option. There is a drum/drum MC from American Motors, that has a place on the bottom of the MC for a brake light switch. I believe this MC is commonly used in hot rods. It also has the correct residual pressure valves for a drum/drum setup. It has a 1" bore which is common for the Ford trucks as well.

 

Use the later Ford switch.
Pic of my '66 shown: