brake problems help

[65Guy]

I put an 85 master and booster on my 65. I have put the prop valve on from the same vehicle. I tried to bleed the brakes with the truck off and on but i can not get fruid the the rear of the truck. i made the push rod long enough to push the brakes almost to the floor before bottoming out. and before i ever push the pedel in my front brakes are locked up. Help me please guys!

[jcrawl]

I hope you get some answers on this one cause i have the same set up 86 disc with the factory valve, so it would be nice to have an idea if i run into the same prob sorry about the problem i hope you get it figured out asap.

[65Guy]

yea ive tried the push rod 2 different lengths and none have worked. i think now i have it too long that is why my front brakes are locked before i even press the brakes.

[jocko]

have you adjusted the prop valve to full rear bias to see if you can get the rears to work (be careful - but just to do it as a check). If unsure which way is which, go full lock one way - test, then full lock the other way (i.e. on the prop valve) and see if the rears ever grab - only do this as a test, don't leave it that way. If rears never work (or if you've already done this) then I'd suspect a bad prop valve. Also, I'd think if your brake pedal almost goes to the floor, then maybe the pushrod is a little too short? That probably isn't the case - especially since you stated your fronts are locking up. But is the pedal spongy? Doesn't seem like it should go almost to the floor.

[65Guy]

Yea I think the push rod is too long, but what is locked on the prop valve?If i have air in the lines still will it be spongy?

[geezer#99]

IIRC there's a button you need to depress and hold in on the front of the prop valve in order to get fluid to the rear drums.

[69pickupnyc]

I had this problem, in fact the front brakes locked up on me. The cause was that when you take your foot off the brake peddle the front brakes don't release completely and every time you apply the brakes the pressure builds till the front brakes lockup. If you remove the rubber stop bushing that the brake peddle hits near the bottom of the dash and the peddle moves just a little forward then this could be your problem. In my case it was the small rod between the power boster and the master cylinder was too long. I corrected the problem by filling down 1/16" the rod and rebleeding the front brakes. I would also check the length of the the rod from the power boster to the brake peddle, if this is not adjusted to the right length this could also cause this problem. I would check with the person who sold you the power boster to see if anyone else had simular problems. Again I woud first check the length of the rod from the power boster to the brake peddle is adjusted properly.

[Captainfab]

I would suspect the proportioning valve is doing it's job. If there wasn't any fluid in the rear lines when you bled the front, the check valve has stopped flow to the rear. Try pushing in on the end of the prop valve where the rubber bulb is. Then crack the rear line at the prop valve and see if you have fluid there. If you can't get fluid out of the rear port of the prop valve, I would just change the prop valve. Then before you bleed any brakes, gravity bleed all 4 wheels until you get fluid each wheel. Then procede with bleeding the brakes manually.

[65Guy]

Thanks guys!