Brake booster and bleeding questions

[msaelens66]

I just converted my 64 c20 to front disc setup with a booster/dual master/ proportioning valve. The rear are drums off a 83 c10. First do I have to have the vacuum port on the booster hooked up or will I just be on manual without vacuum. Stupid cuz why wouldn't you want the assist. Just curious as I have not hooked it up yet and I get a better pedal feel for now. Having said that I can't get Fluid to the rears. Standard bleeding attempted. Bench bled. I have fluid to front and opened line half way to rear and have fluid there. I have had temporary hooked up vacuum by using the line from manifold to pcv but that takes all pedal away while trying to bleed. Any help please?

[MARTYZ]

Yes you do want the vacuum hooked up,make sure your rear brakes are adjusted up, and bleed rears at the wheel cylinders at rear wheels, no fluid back there could be caused by blocked flex line at rear diff, or remove the bleed screws and make sure they are not plugged. Hope this helps!!

[msaelens66]

Thanks Marty , the flex line is the only thing I have not replaced yet. I picked one up today. I thought it was odd that the amount of pedal I do have went away when I temporarily hooked up vacuum. I'll replace the flex tomorrow and try again.

[Captainfab]

If your lines were basically empty when you started the bleeding process, it is possible that the proportioning valve did it's job and blocked off the rear port.

[msaelens66]

I've read about a pin in the front of the proportioning valve. Have not got that far yet. But if the valve blocked of the rear wouldn't I have pedal on the front?

[msaelens66]

What about hooking up the rear to the front port to fill the line, get the air out and test for flex blockage?

[msaelens66]

Captain fab wins with the blocked flex line! Pick anything from the bottom two shelves except the large bear. Thanks cap!

[Captainfab]

That was MARTYZ that mentioned the blocked rear hose.

Glad to hear you got it figured out.