I replaced the original master cylinder with a dual master cylinder-still running drums on all brakes.

https://leedbrakes.com/i-23439162-manual-dual-bowl-master-upgrade-kit.html

Brake lights are not functioning-diagnosed that the pressure brake switch needs to be replaced.

I have a new one to install, but the spot where the brake switch is located.

Is there a tool or tool mod to get in that tight a spot or do I need to remove the brake lines that are on either side of the switch.

Any hints or links that have addressed this is greatly appreciated.

This is the bottom view looking up.

This is the side view.

 

You need a pressure switch socket.
Or…run the wires through the firewall and install an electric switch on the pedal assembly.

 

Or if you really wanted to you could use a nipple and coupling and move it out to where you can get to it.

 

I would try a cloth oil filter wrench. The kind with a cloth band. You can get to your switch from the bottom.

https://www.walmart.com/ip/BikeMaste...SellerId=16532

 

As instig8tr stated - buy a sending unit socket at Napa, probably 15 bucks.





Stepped inside, corners designed not to strip the soft metals of sending units.

 

Just my .02 cents. If you know how a pressure brake light switch works, they do not come on until you are actually applying the brake. I like my Old Iron more than that so I always "switch" to a mechanical switch on the pedal when I get a chance. Most people drive like idiots already, we don't need to slow down their response time as well.

 

When you bypass the original pressure brake light switch, do you leave it in or do pull it & cap it?

btw, thanks for all the help!

rc

 

Best to pull and plug the pressure switch. They can leak. I also converted to a mechanical switch on the brake pedal (70's Ford pickup switch I believe). Popped out the rubber bumper on the pedal and put the switch there.

 

Semi-unrelated question… if you kept it drum drum, why the proportioning valve?

 

Because if you’re running the original one-line, jar type master cylinder and you blow a line or wheel cylinder then you will have zero brakes.
Adding a dual reservoir master and prop valve separates the front and rear brakes. If you blow a rear line or wheel cylinder, you’ll still have front brakes.

 

Yes everyone knows that. In the first thread OP says he switched to dual chamber MC. So that doesn’t apply anyway.
My question was if using a dual MC but keeping drum drum, do you actually need a proportioning valve?

 

NO. As long as you use the correct Ford master cyl. with residual pressure valves in both circuits. But you can use one if you want. The drum/drum dual master cyl. systems did have a differential pressure valve. But all that thing does is turn on a light in the dash to let you know you have a failure in one of the circuits.
Something like this should just bolt on. If you are shopping for one try to find one that comes with the boot and pedal rod.
BrakeBest Master Cylinder - Remanufactured 10-1386 | O'Reilly Auto Par (oreillyauto.com)

 

On my drum/drum, dual MC truck, I use a proportioning valve. I do have 10lb residuals which all drums need.
My rears will lock-up early without the proportioning valve, and I need to dial them down quite a bit to get balance. My truck is not 100% original with a front axle and brakes from a ’74, large wheels and tires, heavy engine, short bed - so my experience could be different from other’s.

 

thanks for the lead on the master cylinder from o’reilly, I didn’t no much more than I did now…still learning.

I bought the tool for the brake light switch. I measured it at 1”.

I found this but it’s a little too big-I thought 1” & 1-1/16” would fit a both sizes?

what does that actually mean?

I’ve never used anything like this before (obviously). Should I return it and get a socket that’s 1@ only?

Thanks in advance,
rtc

 

I was able to locate a socket, locally, that would work.

New brake light switch installed-and they work. Next time around, I’m going to mount the electric switch.

there were a few leaks-they seem to have stopped after snugging down the lines and pumping the brakes.

I usually do a pre-flight before I take Grace out-for any drips or pieces falling off.
(I had the battery tray hold down clank to the ground 😬made one of those tool box empty-ing sounds I don’t like to hear before a cruise)




The socket I found (at one of those auto zone stores) had a 12 point center I don’t remember ever noticing before.

Another reason why got this ol’ girl…to learn.

thanks again for the info.
If you think of anything I missed-let me know. Always ready to learn some more.

rtcapo