Under the floor Master Cylinder - how to mount brake switch?

Have installed an under ther floorboard Master Cylinder. Can't figure out how I'm going to pass inspection getting the brake light switch to work. Issue I'm having is the throw on the new pedal linkage is much more than was on the old set up. The new pdeal comes up quite a distance off the floor, through a long pedal linkage. The old set up had it up close to the pivot point. The new one, the pivot point is obviously down under the car, and don't think the brake light switch would do well under there - getting splashed with water and all.

Be interested in hearing ideas and maybe seeing some pics about how you craetive memebers got around the problem I'm having.

Thanks

Dave

Why not use a presure switch.
Remco

an inline pressure activated switch or weld a bung on the pushrod to the master cylinder and use that bung to activate the switch, if youre worried about how it'll weather then build a cover for it

Yep, an in-line presure switch is the way I went. I would suggest maybe putting it close to the master cylinder before the pressure valve so it gets good fluid pressure.

Jegs part #764-80171 Painless brakelight switch. I installed one in my Falcon this past weekend and it worked flawlessly. use waterproof terminals.

All the old cars had in-line hydraulically operated switches before the electronic ones on the brake pedal.

Put a tee in the line for a pressure switch but make sure the opening for the switch points upward so if you have to change the switch you dont loose brake fluid. Ron Frances sells one that works on low pressure.

70 - 80's era Chevy brake switch.
(Underdash style.)

Part of the arm sawn off.

This is a well protected location, I've driven my 32 roadster in fairly deep water and I don't think the switch has ever gotten wet.

Never had one of these switches fail either.
Lost two hydraulic switches on this car.

The brake pedal is tapped 10-24 for the stainless allen bolt that's locked on with the nut you see.

C9x, I like that solution, got a part #? Joe

C9x - I also like your solution, by the description, but I'm having trouble understanding exactly what I'm seeing in the photo. Is the switch on the back side of the brake pedal? I assume I'm looking at a portion of the brake pedal arm, but am having difficulty distinguishing which is the pedal end, and where the actual switch is in the photo. To the lower left had portion of the photo, that little cicular protrusion, with the nut over it - I'm thinking this is the switch? If so, what does the switch hit to activate it.

Thanks

Dave

Go to your local NAPA parts store and pickup a mechanical brake light switch. It has the mounting hardware included.

Mounts inside, out of the weather and the arm of it presses against the brake pedal arm. When the brake pedal is pushed, arm moves and activates a built-in switch which lights up the brakes. Easy wiring, one connection in, one out to lights. Costs about $12 to 15 bucks.

If I find the Part number, I'll post it.

HYDRAULIC BRAKE LIGHT SWITCH, 1/8" pipe thread fitting, tee in the brake line




http://store.summitracing.com/partde...=KeywordSearch

HYDRAULIC BRAKE LIGHT SWITCHS have always been known to be problems. When used with residual pressure valves the brake lites stay on or flicker. If found to be faulty the brakes have to be re-bled after installation. They haven't been used on auto applications since the '50's, reason, unreliable!

:HMMM: Guess I've been lucky then, been running em on my harleys & hot rods for close to 30 years with no failures.

:HMMM: Guess I've been lucky then, been running em on my harleys & hot rods for close to 30 years with no failures.

I'm with Viking---have been building rods for 40 years with pressure actuated hydraulic brake switches---have never had one fail.

I never had a problem with a hydraulic brake light switch either.

I think this "failing hydraulic brakelight switch" is an urban legend.

Quote:

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Originally posted by brianrupnow
I think this "failing hydraulic brakelight switch" is an urban legend.

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Ditto, more problems with the wiring that with the switch.

Viking and Brian, Where in the line did you put the hydraulic switch? I put mine between the master cylinder and the rear pressure regulator like the Speedway diagram showed, but if the regulator keeps the pressure high maybe it will flicker or stay on? I bought a mechanical switch so I could set it up like C9x shows but I already have the hydraulic switch in the hydraulic circuit. I won't know until I get my wiring in.

Don Shillady
Retired Scientist/teen rodder

I just cut in to the line out of the master cylinder, add a tee fitting for the hydraulic switch and wire it.

Quote:

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Originally posted by brianrupnow
I think this "failing hydraulic brakelight switch" is an urban legend.

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they dont fail...harleys have run em forever...they even work on my chopper flawlessly

I just cut in to the line out of the master cylinder, add a tee fitting for the hydraulic switch and wire it.

Don---I put the tee for my brakelight switch in the front brakeline immediately after the master cylinder, before the residual check valve. Note that the residual check valve holds pressure between it and the wheel cylinder, not between it and the master cylinder.

Joe, no parts # handy, but I'm pretty sure it's a 70's - 80's era Chevy pass car switch and it's probably used in other GM cars of the era as well.

Quote:

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Originally posted by djpritchard1
C9x - I also like your solution, by the description, but I'm having trouble understanding exactly what I'm seeing in the photo. Is the switch on the back side of the brake pedal? I assume I'm looking at a portion of the brake pedal arm, but am having difficulty distinguishing which is the pedal end, and where the actual switch is in the photo. To the lower left had portion of the photo, that little cicular protrusion, with the nut over it - I'm thinking this is the switch? If so, what does the switch hit to activate it.

Thanks

Dave

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That pic is a litle confusing to say the least.

We're looking at the car - 32 roadster with fiberglass encapsulated floorboards - from underneath.
Front of the car is to the left.


The switch is operated by the 10-24 stainless bolt that goes into a tapped hole in the brake arm.

The brake arm pivot point is to the right and that gizmo with the allen bolt in it is the brake pedal return stop.
(I'll post an additional pic or two.)

What I think you're calling the protrusion is one of two - both visible - 1/4-20 nlock nuts that retain an aluminum escutcheon that finishes off the opening and holds the carpet down.

The round can upper right is the switch proper.
It's bolted through the floor with a couple of 8-32 buttonhead allens and you can see their ends in the factory threaded mounting flange.

Reason the switch looks odd is the excess end of the arm was sawn off.

Fwiw, nothing wrong with the hydraulic switches if you run regular brake fluid.

Run silicon fluid - as I do - an the silicon fluid will seep into the switch area and electrically isolate the contacts one from the other and they won't work until the pedal is pushed hard enough to lock the wheels.
The mechanical switch cured that problem.

Incidentally, imho there is no such thing as a low pressure hydraulic switch.
They're all set to close contacts at about 7#.



Here's a pic of a similar brake arm return stop in my 31 on 32 rails roadster project to give you an idea of what you're looking at in the above pic.

This pic shows the return spring setup as well as the brake arm etc. on the Deuce Factory brake/clutch pivot bracket.

It's missing the bolt in side piece that was left off for the photo.

This pic shows what's required for the coil spring return spring setup.

The brake pushrod gets the end sawn off and threaded for the Heim joint. (The threads are there, just hard to see in the pic.)

An aluminum cup was machined to retain the outer end of the coil spring.

Master cylinder is a typical FoMoCo, a Mustang with 7/8" bore in this case.
Note that the coil spring has to be opened up a bit so it will fit over the mouth of the Master Cylinder.

The coil springs are available at many places, Home Depot being one.

C9x---here is a direct quote from Horton Rod Shops catalogue, regarding the hydraulic brake-light switch that they sell.
"High quality switch. Much longer life than previous models available.Fits most cars.Only 20 to 50 pound pressure required instead of stock units that don't come on untill 60-100 pounds of pressure."

Couple things I meant to add.

Be sure and install a zerk fitting in the brake pivot.
I didn't on the 32 and was about a three hour job to do it after the car was up and running.

The Mustang M/C has the brake line fittings exit toward the center of the car.
Not a problem in most cases, but you can get the same M/C - also with 7/8" bore - with the brake lines exiting toward the left side frame rail.
The 32 has such an M/C and it's out of a Torino.
Some of the other FoMoCo cars of the era - 70's or so - have the same deal with the brake lines exiting same direction as the Torino M/C.

Keep in mind the FoMoCo M/C's used in under the floor hot rod setups are in the reverse direction of the stock install.

Quote:

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Originally posted by brianrupnow
C9x---here is a direct quote from Horton Rod Shops catalogue, regarding the hydraulic brake-light switch that they sell.
"High quality switch. Much longer life than previous models available.Fits most cars.Only 20 to 50 pound pressure required instead of stock units that don't come on untill 60-100 pounds of pressure."

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Don't know what to tell you there Brian.

I was quoting the brake supply guy at a parts house.

Regardless, when using silicon fluid, new hyd switches come on with light pedal pressure and a couple months down the line it takes more pressure.
Maybe 4-6 months until excess pressure is required.

I understand the silicon fluid emigrates past the seals fairly easy and the regular brake fluid does not.

Both fluids have their advantages and disadvantages and it's a buyers choice kinda deal depending on what you want to do.

I am leaning toward using regular fluid in the new project.

No probs with the silicon - other than the brake switch.
It has a little softer pedal than regular fluid.

I've driven a friends A roadster with the same brake pedal M/C setup and brakes as my car and his pedal is a little harder, but not much.

Either way, power brakes are not required on these little cars.

Pressure type switches were a cheap and effective way back in the '30's to operate a single brake light on a 6 volt system. Now, with that being said, why would an modern rodder want to use a 70 year old device to provide safety on their car? Hell man, mechanical brakes will stop you if you put enough pressure on them and have enough time to stop before you hit something. You don't go keeping those on your 32 roadster, do you? With 99.9% of the new vehicles having electric switches to operate their brake lights, why wouldn't you want the best deal for your rod?

Sometimes people just go on using the same old thing over and over for one reason only; because they don't know any better. If you are reading this now, we know that you have compute access and you have the world at your finger tips. So why not just punch in " brake light switches" into Google and see what you get. Here's a couple of switches I found that you may find usefull and easy to fabricate into your brake operation.

and this screw in type.

"Pressure type switches were a cheap and effective way back in the '30's"

Yep, and they still are.





"Now, with that being said, why would an modern rodder want to use a 70 year old device to provide safety on their car?"

Cause it still works great.





"Hell man, mechanical brakes will stop you if you put enough pressure on them and have enough time to stop before you hit something. You don't go keeping those on your 32 roadster, do you?"


Yep use em on the 23 bucket, 66 cobra, 53 FLH, 93FLH they stop fine.






"Sometimes people just go on using the same old thing over and over for one reason only; because they don't know any better"


And sometimes people stay with a winner.






It would be a boring world if we all did things the same way huh?, hope you enjoy building rods your way, I know I enjoy building em my way. :toocool:

pressure switch in my '51 Chevy still works great, and it dosn't take very much preassure to work, comes on less than 1/4 of a pedal.