Help Me Set Up my Brakes

[Chevy305]

So I'm about to tear my K10 down to the frame (again) and the brakes need some addressing. The pressure switch on my proportioning valve has failed so my brake light is on all time despite nothing being wrong with my brakes. It's my understanding that the pressure switch can't be replaced by itself, the whole proportioning valve has to be replaced. So my plan was while I had the brake system apart was to replace the valve. But then I thought, hey my rear brakes lock up very easily and far before the fronts do, maybe I need a different proportioning valve (like from a 3/4 ton) or maybe an aftermarket adjustable one. But, can I get an aftermarket valve with the switch built in? I'd like to retain the brake idiot light in case of a brake failure.

My other thought is that I'd like to add a line lock to the system to get those effortless burnouts and easier holding on the boat ramp without having the to shut the truck off in gear. So then how the hell do I add it to a the system I'm trying to set up?

 

[Chevy305]

So what if I use this in the factory location and an adjustable valve down the line on the rear brakes?

http://inlinetube.com/Prop%20Valves/VCT105.htm

 

[Fordum]

OK, real quick like, there is no pressure switch per se on the valve. Its a differential switch.
When there is a difference in pressure between the front and rear systems, it moves off center and turns on the light.
Unless your fluid is full of water and rusty, the switch should be good and you should be able to get the light out.

There are a couple of tricks. If the brakes are adjusted right, sometimes you can just get in and stand on the brake pedal real hard and it will reset.

Otherwise, having someone push on the pedal while you open one side or the other of the valve will create a difference in pressure the other way and move it back.
Tapping on it while doing that may help too...

Of course, an air bubble in either the front or back or badly adjusted brakes can keep it off center until that is fixed.

 

[diesel4me]

The PV in my 82 must be "stuck" too,because it has good brakes ,new lines,etc,but no matter what I do I cant get that dam "brake" idiot lamp to stay off !..so I pull the tan wire off the PV when I go for a sticker,or remove the bulb...luckily the guy I go too for inspection doesn't give it the third degree....pulling the wire is better because the idiot lamp will still work when the e-brake is applied,so it appears "normal"...but if he tried turning the key on without starting it he'd probably notice the lamp wont light up ,then go out as it should if all was working right...

I've tried bleeding the PV right at the line fittings on it,beat it with a hammer,etc,to no avail....doubt I'll ever get around to replacing it either--but finding a stock PV wont be too hard because all GM vehicles from about 1971 to the late 80's used the same style valve,ones on Impalas,Olds Cutlass and Monte-Carlos,etc,are identical to the one on my truck...you could put in an adjustible one but unless your running rear discs or other upgraded stuff you probably dont need one..

 

[Blue85]

Have you tried pushing in on the valve under the little rubber cover? The switch might just be stuck. Although it's more likely there is a loss of rear pressure and the switch is slid towards the rear anyway. Do you have rear drums or discs? You could try taking the switch out and test it by itself. You can also take all the guts of the combo valve out by removing the rear outlet port. Maybe you could clean some crud out or figure out what's wrong in there. You could also try bleeding the system right there with the rear line removed to clean it or burp some air out.

It could also be a master cylinder problem.

 

[Chevy305]

Have you tried pushing in on the valve under the little rubber cover? The switch might just be stuck. Although it's more likely there is a loss of rear pressure and the switch is slid towards the rear anyway. Do you have rear drums or discs? You could try taking the switch out and test it by itself. You can also take all the guts of the combo valve out by removing the rear outlet port. Maybe you could clean some crud out or figure out what's wrong in there. You could also try bleeding the system right there with the rear line removed to clean it or burp some air out.

It could also be a master cylinder problem.

Thanks for the diagram. Is there such thing as a rebuild kit for these?

I haven't tried to adjust or fix anything.

I'm running rear drums on a 6lug 14bsf. So they are bigger than a 1/2 ton but smaller than a 3/4 ton
Maybe I should get a proportioning valve out of a 90s heavy half?

 

[diesel4me]

I've had bad luck every time I tried messing with that pin under the rubber boot on those valves,never had to do that to bleed my brakes good either,after having 2 of these valves screw up after fooling with that pin...I just get another valve complete from a boneyard donor and its always worked for me when I had problems with one...I dont think I'd try taking one apart myself,too likely for it to leak or still refuse to work right with it being a 30+ year old part..

I'm not going to do anything to my truck as long as the brakes work fine and it passes inspection...way my life is going I probably wont own it much longer,ditto for my other "rides".....

 

[Chevy305]

So all the people on here who have rear disks and adjustable proportioning valves can't chime in with an opinion?

 

[Highpsi]

Subscribed.

I'm curious to see any replies about installing a line loc for your e-brake options too. Were you going to keep your factory e-brake setup in place if you convert? I've got a manual transmission so e-brake left fully functional is really important - especially for us guys who want to leave 'er running at the boat ramp while we launch!

 

[Chevy305]

Subscribed.

I'm curious to see any replies about installing a line loc for your e-brake options too. Were you going to keep your factory e-brake setup in place if you convert? I've got a manual transmission so e-brake left fully functional is really important - especially for us guys who want to leave 'er running at the boat ramp while we launch!

I have a functional factory e-brake but its not strong enough to hold the truck on a boat ramp. A line lock would solve my problem for sure.

 

[rampage]

Subscribed.

I'm curious to see any replies about installing a line loc for your e-brake options too.

A line loc is not a replacement for an emergency brake. If you have an emergency, like a brake line busting and you have no pedal, then you wouldn't be able to slow down. Or if you park on a hill, set the line loc and it gradually loses pressure, gravity will take over. You can use a line loc for a temporary parking brake though.

 

[496truck]

Lets not confuse terminology here. These trucks, and most every other car in existence are equipped with "Parking brakes". They are designed to hold the vehicle while parked, not stop it in the event of service brake failure.

"Emergency brakes"... much like ROUS's, I don't believe they exist. Although you could consider the 50/50 hydraulic split system to be an "emergency" function when one side fails.

Drum brakes work best while in forward rotation and kinda OK in reverse, which is why the parking brake doesn't hold on a boat ramp, gravity is pulling the truck backwards. A line lock set up in the front would help to better hold the truck in that situation but I wouldn't rely on it completely. I would use it together with the parking brake.

The front has 2 lines coming out of the prop valve to feed each caliper leaving you with installing the line lock after the prop valve so as not to set the brake light every time you use it. This can be done by plugging one port on the prop valve and using one line out of the other port to go to the line lock then splitting it to feed the calipers. Or, get 2 line locks and tie one into each front line and wire them on the same circuit so they activate together. This second option may be easier as you just have to tie into existing lines instead of running new ones.

 

[Chevy305]

Lets not confuse terminology here. These trucks, and most every other car in existence are equipped with "Parking brakes". They are designed to hold the vehicle while parked, not stop it in the event of service brake failure.

"Emergency brakes"... much like ROUS's, I don't believe they exist. Although you could consider the 50/50 hydraulic split system to be an "emergency" function when one side fails.

Drum brakes work best while in forward rotation and kinda OK in reverse, which is why the parking brake doesn't hold on a boat ramp, gravity is pulling the truck backwards. A line lock set up in the front would help to better hold the truck in that situation but I wouldn't rely on it completely. I would use it together with the parking brake.

The front has 2 lines coming out of the prop valve to feed each caliper leaving you with installing the line lock after the prop valve so as not to set the brake light every time you use it. This can be done by plugging one port on the prop valve and using one line out of the other port to go to the line lock then splitting it to feed the calipers. Or, get 2 line locks and tie one into each front line and wire them on the same circuit so they activate together. This second option may be easier as you just have to tie into existing lines instead of running new ones.

I often find myself reversing with out realizing I left the parking brake on until I try to go forward and its like hitting a wall

I only want to mess with my brakes once. I hate bleeding brakes as I always break the bleader valves off and have to replace the whole caliper or I get brake fluid everywhere or both...

 

[Highpsi]

Ok all.. Point taken, I do understand that a line loc isn't technically a replacement for the e-brake. And I also understand the concept that a hydraulic brake system will definitely bleed off over time and NOT keep the pads applied to the rotor. Boy do I ever understand this - I do technical service for a major powersports company and some of the vehicles they produce don't have a mechanical e-brake setup. I've fielded calls from dealers that have irate customers because they can't rely on the machine staying put for long periods of time on an incline. Even one of the on road vehicles they've started making recently has a completely hydraulic only braking system.

That being said, I just posed the question because of the obvious loss of mechanical e-brakes when you convert to a disc brake setup with a 14ff swap. (Without planning for a cable setup like some of the calipers might have like the Caddy ones or something if memory serves).

Not trying to hijack your thread C305, just wondering what kind of feedback is out there for our similar situations.

 

[Chevy305]

That's exactly why I didn't go to rear disks because I have/want to keep a working parking brake.

But back to my question, do I go to an aftermarket proportioning valve or get a factory replacement?

 

[496truck]

I would utilize a standard replacement, because of it's location and function (beyond just being a prop valve it's also a splitter). Then, if the rears still lock up too quick add an a/m adjustable prop valve into the rear line.

That's my 2c.

 

[Chevy305]

Anyone know what the fitting sizes on the factory proportioning valve are and the associated line diameters?

 

[dremu]

Anyone know what the fitting sizes on the factory proportioning valve are and the associated line diameters?

Starting at the end with the rubber button, above and below this are front outputs which are 3/16" lines, the fittings for which use 3/8" wrenches. I think Edelmann calls this a 3/16" fitting.

The front inlet port is a 3/16" line also, but with a larger fitting that uses a 9/16" wrench, I believe the one Edelmann calls 9/16-18 (see below.)

The rear inlet port is a 1/4" line which uses a 7/16" wrench. I believe Edelmann calls this a 1/4" fitting.

Finally we go to the far side end, which is the the rear outlet line. The line should be 1/4", but uses the larger fitting which uses a 9/16" wrench.

Edelmann makes these ends in many combinations of fitting and line size if you want to flare your own: http://www.plews-edelmann.com/inverted-flared-tube-fittings/

Go to "Standard Steel Nut - Inverted Flare" and click "Show Product Info".

This is measured on both a factory valve and a new aftermarket one I have from Inline Tube, as well as one of their line sets, which is all sitting on the bench awaiting installation. Once it's light tomorrow I can crawl under either of my trucks and verify anything specific if you have questions.

EDIT: here's a picture I did up for another thread that shows the layout:

-- A

 

[Chevy305]

Thanks Dremu, that's exactly what I was looking for

I'll be making my own front lines to accommodate for the line lock. I'll be ordering a replacement proportioning valve from InLineTube as well as the bulk lines and fittings.

 

[dremu]

Thanks Dremu, that's exactly what I was looking for

I'll be making my own front lines to accommodate for the line lock. I'll be ordering a replacement proportioning valve from InLineTube as well as the bulk lines and fittings.

No worries. I just happen to be doing this now, so it's easy. Next month, or whenever I finish, this woulda been more work

Note that you gotta be careful of the lines at the master cylinder, as the master cylinders for vacuum and hydroboost are different, different years are different, etc.

But if you're just cutting into your front line and not changing the master, this should cover it.

-- A