Hydro boost and rear brake setup question

N

Nurse

Member
Chevy astro van hb and prop. Valve....

I did billusn-1's hydro boost convertion this summer. Copied everything he did. I still don't have much if any rear brakes. I tried it out on the slick/icy roads around the house today and can't get them to lock up on black ice. I have brake fluid going to the brake cylinders when I bleed the brakes. I don't get a good "stream" of fluid when bleeding though.

I guess I'll start by replacing both rear brake cylinders in hopes that they are at fault.

The rear shoes are new and set up right. I know bill has had good luck with his van prop valve, but I just don't think I'm getting the pressure back to the rears. I have a traveler vs bill's Scout II, but I wouldn't think that a foot more brake line would make a difference.

Thoughts?

Thanks!

-t
 
You should have a massive pressure reading at each rear wheel cylinder inlet (about 1/4>1/3 greater pressure than with the oem master cylinder)! If the rear brakes worked before, they will work now if nothing back there changed. Verify that the steel line run to the rear junction is not obstructed from something that came out of the junkyard shit!!

Is the proportioning valve a boneyard part??? I never found a boneyard unit that is any good! Especially if the system has been sitting "open" to the atmosphere. Get rid of it (bypass) with a union fitting temporarily and then see what kinda pressure ya get at the rear wheel cylinders. If that does it, then stick a wilwood adjustable valve in place of the union and dial it in! Run the front brake circuit with a union and toss out the junk boneyard p-valve, those will kill you and you will end up in your own place of employment!

So the front circuit is run full pressure, the rear circuit is dialed back a tad using the adjustable proportioning valve.
 
michael mayben said:
you should have a massive pressure reading at each rear wheel cylinder inlet (about 1/4>1/3 greater pressure than with the oem master cylinder)! If the rear brakes worked before, they will work now if nothing back there changed. Verify that the steel line run to the rear junction is not obstructed from something that came out of the junkyard shit!!

Is the proportioning valve a boneyard part??? I never found a boneyard unit that is any good! Especially if the system has been sitting "open" to the atmosphere. Get rid of it (bypass) with a union fitting temporarily and then see what kinda pressure ya get at the rear wheel cylinders. If that does it, then stick a wilwood adjustable valve in place of the union and dial it in! Run the front brake circuit with a union and toss out the junk boneyard p-valve, those will kill you and you will end up in your own place of employment!

So the front circuit is run full pressure, the rear circuit is dialed back a tad using the adjustable proportioning valve.
Click to expand...

The first proportioning valve was from the donor van. I then bought a new valve off ebay because I thought the first one was junk.....didn't help the problem.

-t
 
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