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KV Racing

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I have a 1956 all original 1956 F100. What's the issue with the brake lights? The pressure switch is a known problem on these 50s cars if you still have the original signal master cylinder

It's all stock although the pressure switch and master cylinder have been replaced. It's definitely in the switch, or more accurately, in the pedal assembly. When you drive the car, it's fine. Stop and let it sit for 10-15 minutes, the brake lights come on and stay on. Pull up on the pedal and they go out. Wait 10-15 minutes, and they come back on. I'm not sure if the return spring isnt strong enough to keep the pedal at the correct height, or if there is something else letting it "sag" putting a hair of pressure in the system making the lights come on. I was told on the HAMB it is adjustable, but I havent crawled under there yet and pulled the boot back to see what they are talking about. I am leaning towards the pedal return spring being the issue, but I wont bet a dime on being correct at this point. :headbonk:
 
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It's all stock although the pressure switch and master cylinder have been replaced. It's definitely in the switch, or more accurately, in the pedal assembly. When you drive the car, it's fine. Stop and let it sit for 10-15 minutes, the brake lights come on and stay on. Pull up on the pedal and they go out. Wait 10-15 minutes, and they come back on. I'm not sure if the return spring isnt strong enough to keep the pedal at the correct height, or if there is something else letting it "sag" putting a hair of pressure in the system making the lights come on. I was told on the HAMB it is adjustable, but I havent crawled under there yet and pulled the boot back to see what they are talking about. I am leaning towards the pedal return spring being the issue, but I wont bet a dime on being correct at this point. :headbonk:
Where did you get the psi switch? Also is this still a single bore master cylinder? You may be correct about the spring. Check Dennis carpenter for a new psi switch, some of the aftermarket ones are known to stick and do exactly as you mentioned. Did you use DOT 3 brake fluid?
 

KV Racing

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Where did you get the psi switch? Also is this still a single bore master cylinder? You may be correct about the spring. Check Dennis carpenter for a new psi switch, some of the aftermarket ones are known to stick and do exactly as you mentioned. Did you use DOT 3 brake fluid?
Everything we have replaced on the car has come from Dennis Carpenter. Since the switch was cheap I bought a second one, and it does the same thing.
Yeah, the master cylinder was a stock replacement from D.C.
Yes on the DOT 3 fluid as well. Should I have used something different in it since it is an old vehicle? We replaced the wheel cylinders and one big hunk of brake line as well after we got the car.

Just a little back story on the car. It was my gf's father's car. He purchased it from the original owners (literally, an old couple) in 1958. He drove it for a couple of years as an every day driver, then bought something else and drove it very infrequently after that. In 1977 he parked it in the garage and it sat there until he passed away and we got the car in 2008. It is a survivor car, and has 38K original miles. It has been a learning curve for me trying to get this thing back to a point where we can take it to cruise ins and drive ins.
 
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Everything we have replaced on the car has come from Dennis Carpenter. Since the switch was cheap I bought a second one, and it does the same thing.
Yeah, the master cylinder was a stock replacement from D.C.
Yes on the DOT 3 fluid as well. Should I have used something different in it since it is an old vehicle? We replaced the wheel cylinders and one big hunk of brake line as well after we got the car.

Just a little back story on the car. It was my gf's father's car. He purchased it from the original owners (literally, an old couple) in 1958. He drove it for a couple of years as an every day driver, then bought something else and drove it very infrequently after that. In 1977 he parked it in the garage and it sat there until he passed away and we got the car in 2008. It is a survivor car, and has 38K original miles. It has been a learning curve for me trying to get this thing back to a point where we can take it to cruise ins and drive ins.
I'm not to familiar with your car, but the f100 trucks have the master cylinder under the driver side floor board. On the trucks their is a return spring and since mine is a 4 speed Manual, the pivot points are on the same mount. The trucks have a grease zerk and it's important to make sure it's not sticking. Do you have all the drum brakes adjusted right? Does it stop straight or pull to one side? When you installed the new master cylinder, did you bench bleed it first before installing it? DOT 3 brake fluid is the correct fluid. Make sure that when you bleed the brakes that you do the right rear first, then the left rear, then the right front then the left front last. Make sure all the brakes are adjusted correctly. "IF" your brake pedal goes soft or to the floor, you may have air in the brake system and this could be causing your brake lights to come on after parking it. Air does not compress. If you still have a single bore master cylinder, be very careful, if the master cylinder goes bad, you lose all 4 brakes. Unlike a modern car you have 2 reservoirs. If one goes bad you can still stop. Not so on older cars with single reservoirs. It's smart to have a more modern master cylinder. I myself still have the single lol.
What year is your car? 49-50 or 51?
What engine? Hopefully a flathead V8!
Manual brakes? Or vacuum assist?

I love old ford cars and trucks!
You have any more pics? I'd like to see them if so.
 

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It's a '51, flathead with a 3 on the tree.
Yeah, the master cylinder is under the driver's side floor and there is a grease fitting on it along with one big return spring. The car stops straight and stops pretty good considering it has manual drum brakes. The pedal isnt soft, but I could always bleed them again just to make sure. At this point it cant hurt anything.
It's still a single bore master cylinder, but at least it's new. And worst case scenario, the parking brake still works. LOL
 

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We also have this that is almost back to a state where it can be driven again. A slight issue with the brake lights is all that is left. Once I get that figured out, it will be cruise in and drive in worthy.

Love shoe box Fords are you still running the flat head engine. :thumbsup:
 
 




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