Brake proportioning valve question

[crewsr]

The braking in my 71 C10 is pretty poor. It's disk/drum, no power assist. I have within recent memory installed new MC, calipers/cylinders, disks/drums etc. The prop valve currently on the truck has 2 in and 2 out and no bleed 'button'; I'm not really sure if it's the correct one for disk/drum (previous owner mentioned that he had converted the fronts to disk, but I don't really have any details). I've purchased a new prop valve which is 2 in and 3 out; there are separate outputs for the each front wheel. Without changing my brake lines what should I do with the extra port? I've seen some pictures of others with the same (or similar) brake lines where there's a 3/8-24 brass bolt screwed in to this port (the new prop valve did not come with one). I've also seen some pictures where a 't' and some short sections of brake line are used to merge these two and connect them both to the existing front line. I'd prefer the first option as it looks much cleaner; is there anything special about the bolt for this? Is it safe to just get one at the hardware store and use thread tape?

[RodnRudy]

No don't use a regular bolt. Go to your NAPA store and ask for a 3/8 24 inverted flare plug for that extra hole. Take the valve with you and show them where it goes and they will be able to fix you up.

[geezer#99]

Originally Posted by crewsr

The braking in my 71 C10 is pretty poor. It's disk/drum, no power assist. I have within recent memory installed new MC, calipers/cylinders, disks/drums etc. The prop valve currently on the truck has 2 in and 2 out and no bleed 'button'; I'm not really sure if it's the correct one for disk/drum (previous owner mentioned that he had converted the fronts to disk, but I don't really have any details). I've purchased a new prop valve which is 2 in and 3 out; there are separate outputs for the each front wheel. Without changing my brake lines what should I do with the extra port? I've seen some pictures of others with the same (or similar) brake lines where there's a 3/8-24 brass bolt screwed in to this port (the new prop valve did not come with one). I've also seen some pictures where a 't' and some short sections of brake line are used to merge these two and connect them both to the existing front line. I'd prefer the first option as it looks much cleaner; is there anything special about the bolt for this? Is it safe to just get one at the hardware store and use thread tape?

Do you have a pic of your prop valve?
Maybe that one port is for the warning light.

[crewsr]

I don't have a picture of the either, right now. The new one has two inlets at the top (in from MC), along with the installed warning switch. There is a port to the 'rear' (facing the firewall) for the back brakes, and port on the bottom towards the front (left front wheel, this one matches my lines perfectly) and a port at a the front (right front wheel, I have no brake line for this). The 'bleed' button is on the front between the two front wheel ports with a little rubber cap. There are any number of pictures of this ordinary brass prop valve kicking around, it's pretty common.

The old one is cast steel, two ports on the top (in from MC), one port to the rear (back brakes) and one port to the bottom (front brakes), along with the switch port. This one also has an additional port in which there is a bleeder screws. The bleeder screw does not fit the new prop valve.

I found the plug RodnRudy mentioned above at my local Autozone store. Disappointingly, the counter guy at Napa had know idea what I was talking about...

Thanks for your replies; I think I should be able to make it work. Between this and new hoses, I hope I can get some improved braking.

[MagmaJct]

If your hard braking doesn't clear up after this repair, make sure your idle speed isn't too high if you have an automatic.

I too have no power brakes, and if the idle speed is set too high, it's a pain to stop, and the idle creep is bad when I'm at a light. I once nearly rear ended another vehicle at a stop light because I bent down to pick something up off the floor!

[crewsr]

Thanks for the input. Manual gearbox. The new prop valve and rear hose has helped the stopping and brake pedal feel significantly. However, I am having issues with the 'plug' not sealing in the prop valve. The two different plugs I've gotten (1 from Napa now, one from Advance O'Autozone) have inverted flares that look too large in diameter to fully seat on the mating flare 'cone' inside the prop valve. It's like it needs a little crush washer or something... I'm irritated. I've tried snipping the flare off a piece of scrap line and inserting it into the cavity of the plug (in other words, using the line flare as a crush washer), but it's simply too thick and plug only engages like 2 threads (not enough) before bottoming out.

I don't really have loads of time to goof around with it, so I may wind up simply redoing the front lines where they 'T' down at the frame rail, and use both ports on the prop valve (i.e. keep both left & right lines separate all the way to the prop valve).