Brake System Question

[Barry Maxwell]

I am in the process of removing the various wiring harness's from my '51 B3C and tagging the wires. When I got to the harness that runs back to the tail lights I expected to find the stop light switch mounted on the top of the master cylinder (where the parts manual indicates it should be). In place of the switch there is a plug.

The line coming out of the bottom of the master cylinder goes to the rear and supplies a unit I can't identify (photos attached) that is attached to the inside of the frame rail at about the mid point of the battery box. The line enters the unit on the left where the stop light switch is located. The outlet pipe on the right goes to a splitter with three outlets - two to the front (one for each front brake) and one to the rear where it splits again on the diff. housing for the rear brakes. Further, the unit has two wires coming out of the top - one that is cut off and one that goes back into the unit.

Can anyone identify the unit? In its earlier life the truck was equipped as a wrecker with a hoist on the bed. I can only assume that either the parts manual is wrong or this unit was added for some reason. Any help will be appreciated.

[Dave72dt]

I'd have guessed a MicroLok for the brakes or some kind of proportioning valve.

[Merle Coggins]

I'm with Dave on this. It sort of looks like a brake lock solenoid. The wrecker driver would apply the brakes and flip a switch that would activate the solenoid and lock the pressure in the rear brakes. It's sort of a loading brake used to hold the truck rather than rely on the driveline parking brake when pulling a vehicle with the winch. The brake light switch is then on the output side so that the lights would stay on when the brakes are set.

This is definetly an aftermarket add on. I wonder if it still works?

Merle

[Barry Maxwell]

You guys nailed it. I went back to my box of misc. parts stripped off the truck several months ago. One was a two wire toggle switch mounted to the left of the steering column marked "Mico Brake Lock". Another part is a red light mounted where the ash tray would normally be. It is marked "

Signal-Stat" model 107 with "Flarestat" marked on the red bulb cover. Since it has four wires out the back, I am not sure that it is connected. There is also a bar of roof lights and several other extra lights that were in the box before I got the truck. It may be connected to those - I can't tell.

I hooked up the wire that was cut off, and nothing happens. I THINK I have a good ground. If so, the solenoid doesn't work. Not surprising after all these years. It really doesn't matter since I will remove the unit once I get the cab off (whenever that is) and I have room to work.

Thanks guys. As I have said before - Whata Forum!

[Merle Coggins]

The Signal-Stat thing is most likely part of the flasher unit for your roof mounted warning lights.

Merle

[Dodgeb4ya]

I have MoPar one on my truck-still works too.

[Paul Hatfield]

I was reading this thread and remembered 40+ years ago my Dad teaching me about the 51 truck we had back then.  He told me that when parking on a steep hill to put my foot down on the brake hard, and while holding the pedal down, throw the switch.  Said it was good insurance over using the parking brick we kept in the bed of the truck 

Anyway, I looked in the parts manual, and on page 1-14 there is a section for a "BRAKE HOLDER".  See 1-43-1 part number 1266 969  

 

Could this be in fact a factory option??

 

Paul

Edited October 21, 2014 by Paul Hatfield

[DJ194950]

A factory brick option? Factory name on it? Picture?

 

DJ

[Plymouthy Adams]

brake holder or as they were popularly known as "hill holder" were a popular option on many makes back in the day..my 50 Stude is so equipped with one...they were used to hold a hill and thus save wear and tear on clutches and not for parking...as they were electrically energized..once the ignition is off so are the brakes..

[MBF]

I think you may have also had to step on the brake pedal after turning the switch off to release the check valve in the solenoid.  With the mechanically valved version, I know that had to be done after you moved the lever.    Mike

[BigDaddyO]

It's supposed to be plumbed into the front brakes for doing burn outs and drag racing starts at 'the tree'.

[Paul Hatfield]

Mike-

 

You may be correct, but it's been to long for me to remember.  I do think we used it for parking the truck on hills, which would mean that we turned the ignition off after setting the switch.  Perhaps in that truck it was wired to have constant power to the switch, which might not have been stock.

 

All this was back in 1969 when I turned 16.  I later sold the truck for $300 but it sure was fun to have during High School.

Paul

[Jeff Balazs]

There is an explanation and drawings of how this option worked in the B series Workshop manual. I had no idea they had something like this until this topic came up.

The stuff you learn when you read all of these..... hey.?....

 

Jeff

[Dodgeb4ya]

It's a MoPar truck option also found on the Route vans since they were door to door delivery.

To use it you come to a stop and with the brake pedal depressed turn the dash switch to on.... when ready to release the brakes and drive off push on the brake pedal and turn the switch off.

 

A pic of the factory dash switch and instruction plate...

Bob

[Paul Hatfield]

BINGO!

Thanks Bob!

Paul

[Jeff Balazs]

Huh? The one I saw in my manual looked as if it was a M/C with a built in solenoid. I will have to look at it again. Maybe there were different variants of this option?

 

Jeff