1939 Ford Brake Light Switch

The kind of messy way I've done it is to apply VERY SLIGHT pressure on the pedal to keep a minute amount of fluid flowing outward while I unscrew and then reinstall the switch. That keeps the fluid pathway full and doesn't allow air in as you slowly screw the new switch in place. It's worked for me on both old Ford and motorcycle switches, but one must be careful of the pressure or you get a big mess. Keeping the fluid path full, esp as you install the new switch, is the key.

 

If your using silicone fluid, it eats brake light switches. I install a 49-5?? chevy lever switch
under floor under brake pedal arm. End of problems.

 

you should try the harley pressure switches too. Little more spendy but last lots longer and are more in tune with modern brake fluids.

 

Used the same approach as suggested by Crestliner. Installed a mechanical lever-arm switch from a 1956 Chevy pickup. Don't know the part # but it's readily available at NAPA, O'Reilly's, etc. Cheap and not affected by silicone fluid.

As for replacing the switch without having to bleed lines, the slight pressure suggestion seems a good one, but that turns it into a two-person operation ... which is pretty much what bleeding the brakes requires -- unless you have the right tool!

 

I might be totally backwards but just fill the reservoir to the top and replace the switch....refill the reservoir and cap.
there shouldnt be any ****ing of air as the switch end should be only where gravity takes the fluid.

 

Screw a '55-'60-? Chevy truck lever switch to the bottom of the toe board.
problem solved.
Brake arm physically closes and opens it.
I bought three at NAPA for about 6-8 bucks? put them away for other projects.
That's what I did on my GMC after the first new pressure switch went south.
I didn't know it was bad because when I tested it in the drive way, you know, stand on it and have someone say "yea. they work" was good but just going down the road using light pedal they don't light up. Someone in our club told me they didn't work after we caravanned somewhere...
Put a mechanical switch in it.

 

I must have gotten lucky. I didn't bleed the system or do anything more than replace the switch on mine.

My next project is to do a full system flush as my fluid looks more like sewage than brake juice.

 

I always use one of these. The one on my 32 Roadster is almost 20 years old and the one on my 32 3W works perfectly also.

I got mine from SO-Cal but others sell them ... like on the dreaded auction site ( FLEA-BAY ).

 

Ryan,

http://www.oreillyauto.com/site/c/detail/BOR0/S233.oap?pt=02071&ppt=C0039 this is the part number for the Chevrolet stoplight switch. I just left the old Ford switch in place and mounted this one on the floorboard of my .50 Fordor. Much more dependable.

 

I'm converting my old '36 roadster over to 12 volts and while Im at it ,Im converting over to a mechanical switch. I sourced one from a local supplier. The switch looks like it originated from Speedway motors so the part number appears in the lazily scanned image.
The attached text scan is from a newsletter that I receive and it touches on this subject, so someone probably might benifit from the information that it has.
A Harley Davidson switch relies on less pressure to activate so it over comes the problem of no brake lights activating when soft application of brakes is required, and that should be most of the time!
The snippet is taken from a 'restorers club' newsletter so it is proof that they in fact 'do' modify their cars LOL!

Hope this helps! Hot-Rod Dude

 

if its not leaking hydraulicly why not use a motorcycle back break switch hooked to a spring then to the brake pedal.. no bleeding required...

 

If the switch isn't leaking, leave it in place and install a mechanical unit.
There is a guy on ebay selling misc lever action switches for fairly cheap.
It doesn't matter what the original switch was made for as long as you can
mount it to a bracket that will cause it to be activated by the swing of the pedal.


.

 

This is exactly what I just did on my 39 a few weeks before Christmas. I had no problems and no air in the lines. I also found a newer style switch that only requires light pressure for the lights to come on. I can try to find the info on that switch if your interested.

Murph

 

Another vote for the lever switch. I use the same kind pictured in the Orielly's link above. Cheap and easy. No need for the fancy adjustable arm kind (sorry Duece Roadster), you can bend the steel arm on the regular one just fine and the screw won't come loose.

 

If you installed the switch fitting in a position that faces up to feed the switch you should only lose pressure and not allow an air bubble to be trapped. You would remove the switch, place the new switch in, lightly touch the brake lever to allow the trapped air to escape and flush fluid through the loose thread, upon seeing fluid the switch would be tightened, do not let up on the lever until the switch is tightened or air will be drawn in. This should give you an isolated line bleed of a branch in the line, since the air could not have escaped into the main line, the line should not require a full line bleed. If you placed the switch on its side you would have to loosen it slightly in the line while the system is under slight pressure and rotate it up so as not to introduce air into the line. I also use the Harley or Ron Francis Silicone switches.

 

I too went to the lever switch.

 

Just depress the brake pedal slightly, about 1" down, block it from the seat front with a piece of wood dowel (old broomstick) or a telescoping brake pedal strut tool.
The idea is to push the piston past the residual valving. Remove the old switch, and start the new one, just 2 threads, not snug. REmove the strut, tap the pedal lightly, (not pumping, just going past residual valve; the small amount of fluid that will drip can be contained in a couple of shop towels underneath) Now reach under and tighten the switch.
Good operation, no air in lines this way...
NAPA has a later Ford pickup switch that is good quality, with the right thread.

Or fix it as suggested with Chevy parts...

 

I have replaced a handful of those stock switches in my 40 coupe over 45 years. With the last build I installed one of the lever switches with no problems. I also installed one in the 40 pickup I'm building. So easy to install.

 

One more vote fore a mechanical switch. I find too many problems with the pressure switches, and replace them with mechanical switches often

 

I never realized there was anything wrong with the stock switches. Guess I'll throw another $3 one in my toolbox just in case.

 

One of the good things about a lever switch, is that the movement wipes the contacts clean inside, which pressure switches don't do.

 

ok, maybe I got a bad one, but when I was checking one of these switches with my DVM, It shows to only be closed when it is at rest. Then it opens when I sweep the arm for most of its travel. I'm confused because it seems like it ought to be normally open, then closed for most of its sweep. My switch looks like the ones posted. Were there maybe different types? I bought it loose so I don't know for certain its application, but looked like a NOS switch for a Chevy.

 

Hi guys!
I own several soviet made cars (1963 Volga (GAZ-21), 1981 Volga (GAZ-24)) and have seen a lot of soviet vehicles using same type brake switch.
I was quite surprised while working on my friends VW Beetle that this car has same switch
I tried to install it on Volga and BINGO - the same threading etc except wire connector.
It is quite hard to find working soviet made switch here. Last time I bought about 8 switches and they all appeared bad.
So I had to install VW switch and replace original wire connectors with modern ones.
Then I start thinking about history of GAZ plant and the fact it was build under supervision of Henry Ford forced me to perform some googling I found out that 1939-~1948 Fords used same type brake switch and it even has same type wire connector. So can anyone tell me the threading parameters of Ford switch? I wonder will it fit Volga's brake system and look like stock one

 

I changed the one on my Ford last year, no bleeding was required. I had a NAPA switch in it, took a lot of pressure to trip it. Found a source on eBay, 45 psi line pressure and the lights go on. I also make a point not to stand on my brake pedal for extended periods of time. I believe this is what kills them early.
https://www.ebay.com/itm/Chevy-Ford...ash=item2ed977ef28:g:rQIAAOSwr1tZ8jxz&vxp=mtr

 

I have replaced several and bleeding was never required.

 

I used the Harley Davidson switch

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