Power Disc conversion/ proportioning valve question

[4mulas]

Calipers are fine, use the bleed screw furthest way from the brake line/inlet (the one closest to the hood of the car. They look like the ones doctor diff sells with the two bleed screws.

I respectfully disagree with jcb426. No need for Teflon tape on the bleed screw. If they don’t leak fluid when the brakes are applied and held they certainly won’t suck air when the peddle is left off.

 

[jbc426]

Calipers are fine, use the bleed screw furthest way from the brake line/inlet (the one closest to the hood of the car. They look like the ones doctor diff sells with the two bleed screws.

I respectfully disagree with jcb426. No need for Teflon tape on the bleed screw. If they don’t leak fluid when the brakes are applied and held they certainly won’t suck air when the peddle is left off.

I fully agree with your bleeder positioning analysis, but I respectfully disagree with your second statement. I think there is a misunderstanding of what I was trying to illustrate here. You are right, the Teflon tape is not needed to seal a closed bleeder screw, as they seal with an angled seat and tapered bleeder screw end.

However, the Teflon is often needed when the bleeder is cracked open, with a preferably clear plastic tube fitted over the tip to direct the fluid into a clear jar, so you can see any bubbles. The Teflon around the threads comes into play at this time.

I say this because, most of the bleeder screws I have dealt with will seep fluid around the threads when they are unscrewed even slightly. This "leak" can potentially allow air back into the system during the bleeding process. It's happened to me numerous times.

 

[RLF Cuda]

I ran across this video from McCalla's Modified Rides showing install of a '73+ proportioning valve on an early A-Body. Seems reasonable. On my car ('68 Formula S FB), I ran '78 11.81" rotors and a Mancini adjustable proportioning valve in place of the factory value (original KH Disk Brake car) and got it adjusted so the fronts lock just before the rears. Beast brakes I have ever had on a car.

 

[bahamabecomb]

Here is where I am at this morning. Having someone hold the brake pedal until the brake light comes on, open any of the front brake bleeders the light goes off and pedal goes to the floor. close bleeder and press brake pedal, light comes on again. For the rear brakes with the pedal pressed until the light comes on if either bleeder is opened I get fluid out (not as strong as the front), brake light stays on and pedal does not drop to floor. Not seeing bubbles come out of any of the bleeders. I think the next thing is to replace the proportioning valve?

rlf-cuda, I don't see an attachment for the video

 

[RLF Cuda]

There seems to be a number of videos on proportioning valves and distribution blocks if you want to research this further.
Found this on E-Bay, but no idea how good it is. 69 74 Mopar A B body Disc Brake Distribution Brass Block Proportioning Valve | eBay

 

[Inertia]

Here is where I am at this morning. Having someone hold the brake pedal until the brake light comes on, open any of the front brake bleeders the light goes off and pedal goes to the floor. close bleeder and press brake pedal, light comes on again.

When the lite came on, pressure had been lost on one side/system.
Opening fr bleeder and lite going out equalized pressure to zero, lite off, - secondary system (rear) failed as pedal went to floor, - if properly bled !

For the rear brakes with the pedal pressed until the light comes on if either bleeder is opened I get fluid out (not as strong as the front), brake light stays on and pedal does not drop to floor. Not seeing bubbles come out of any of the bleeders.

Lite staying on indicates shuttle is already triggered to failed side (rear), - pedal not going to floor indicates front system holding pressure as it should, and applying front brakes.

If there has been no fluid loss outta rear brake reservoir, other than accounted for by bleeding.
I would suspect master cylinder, except pedal should be "disappearing" - creeping to floor till lite comes on.

Is pedal close to top and firm/hard when first applied, or does pedal go down a bunch till you feel "pedal"/resistance. ?
If it goes down a bunch first, you need to adjust the rear brakes, and/or properly bleed.

Good luck .

 

[bahamabecomb]

Correction on my part, I had not put the drums on the rear for the test (idiot). Now with the drums on light goes out when bleeder is released just like the front.