• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Proportioning brake valve, Question...

Lineman

Well-Known Member
Local time
9:33 PM
Joined
Jun 24, 2017
Messages
145
Reaction score
30
Location
Glen Burnie, MD
So please tell me about what exactly triggers the brake light on the dash. I assume when that pin on the valve either grounds for not? But what goes on with that pin? Is it supposed to move? Or be adjusted? In case of a open circuit front or rear I assume the pin moves, lights the dash and closes the open circuit? If so what should be checked/adjusted?

FYI - I am getting a intermittent light on the dash but mostly it is staying on. And yes I have been fooling with the brakes six ways to Sunday... but I think now they are working really nice. Scary nice..

69 GTX power disk.

Thanks for the help.

Jay
 
Sorry not much help but figure their is a spring in the valve that trigger's the switch. With out pressure. On it will alarm or turn warning light on. Got a new one when doing my resto. Did not trust the old part. Figured it was 50 year's old so out with the old and in with the new.
 
Are you sure the problem isn't with the parking brake switch ??? That's just a contact switch that's easily triggered if out of adjustment or the pedal is loose, etc..
 
Are you sure the problem isn't with the parking brake switch ??? That's just a contact switch that's easily triggered if out of adjustment or the pedal is loose, etc..

Thanks, I looked at that. i can check again long story but I was fooling with that pin on the valve and it seems to move in the block... Not sure what is going on there... I was hoping to understand a little more before I got to fooling with it..

Thanks

Jay
 
When air enters the seat for the pin that's when it's grounded and the light comes on. So when this happens and you fix the problem, say low brake fluid in the master cylinder and you had to bleed the brake lines, you still might have a bubble of air at the pin. All you do is loosen the nut, lift it out then place back in and that should release the bubble of air. The light should go out after this. Otherwise there might still be air in the system.

Checking the e-brake switch a good idea also.

Good luck!
 
So please tell me about what exactly triggers the brake light on the dash. I assume when that pin on the valve either grounds for not? But what goes on with that pin? Is it supposed to move? Or be adjusted? In case of a open circuit front or rear I assume the pin moves, lights the dash and closes the open circuit? If so what should be checked/adjusted?

FYI - I am getting a intermittent light on the dash but mostly it is staying on. And yes I have been fooling with the brakes six ways to Sunday... but I think now they are working really nice. Scary nice..

69 GTX power disk.

Thanks for the help.

Jay

A Proportioning brake valve works off pressure. It is basically a pressure differential valve. It works completely off of pressure. With the dual master and designed system working properly the valve stays centered and electrical wise open circuit so no light. When the pressure goes unbalanced the valve will slide one way or the other tripping the switch to ground and causing the light to come on. Common causes are master cylinder failure, to much travel on the mechanical side. Once you have bled the system air should not be a problem. As said make sure the emergency brake is not causing the light. You could unplug that switch temporally while trying to figure out the problem.
 
When air enters the seat for the pin that's when it's grounded and the light comes on. So when this happens and you fix the problem, say low brake fluid in the master cylinder and you had to bleed the brake lines, you still might have a bubble of air at the pin. All you do is loosen the nut, lift it out then place back in and that should release the bubble of air. The light should go out after this. Otherwise there might still be air in the system.

Checking the e-brake switch a good idea also.

Good luck!

Thanks, I was messing around with a test light on the pin while I was bleeding the brakes for a bit and nothing really seemed to work with that idea... But that pin where the light connects seemed like it was moving in and out of the block some as I pushed on it? Could that be right, with the outer nut tight I never loosened that..??
 
I had a C-3 vette once and after doing the brake work they wanted you to hammer on the brake pedal as hard as you could with a quick firm jab. Must have rebalanced the pressure in it, not sure, but it worked and the light went out. Not sure if this technique works on a mopar valve or not…. But maybe.
 
Thanks, I was messing around with a test light on the pin while I was bleeding the brakes for a bit and nothing really seemed to work with that idea... But that pin where the light connects seemed like it was moving in and out of the block some as I pushed on it? Could that be right, with the outer nut tight I never loosened that..??

Yes the pin should move in and out.
 
Thanks for the help, I had to dig this thread up. So now I got the light on the dash to go out by pulling the pin out and putting the wire on the end of the pin. The pin really seems loose and wobbling around in the valve. There is a nut on the pin and I really don't know what it is for? Maybe a jam nut for the wire? Until I pulled the pin all the way out of the block the light (on the dash) would go off and on in general and as the car would hit bumps etc.. Now as I drive the car some I am starting to realize it seems to be stopping with the rear brakes mostly.. So is that part of this puzzle??
 
20443F4E-B85C-4B1C-8A8E-3E87B1D4DF6F.png
 
So you can see that my car is not plumbed as the picture. Its a disk brake car and I have the valve in the line going to the rear brakes but I don't have the metering block for the front brakes? So what is going on here? Thanks Jay

2021-09-04 08.43.58.jpg Screen Shot 2021-09-24 at 9.58.02 PM.png
 
Not all B bodies had them. I believe they were installed, when the single piston calipers came out in 1970. They held off application of the discs until the rear drums started to engage, which was beneficial in slippery conditions.
 
Auto Transport Service
Back
Top