Brake Question

[nemesis_pyros]

OK odd question. How long are the "plungers" the that sit against the wheel cylinder on a 14bff. And how far should the pistons be compressed when I put the drum on?

I'm Trying to figure out a long time brake problem and i've narrowed it down to the rear axle.

 

[nemesis_pyros]

ttt for the evening crowd

 

[Pvt. Maggot]

Shouldn't stick out too far, If they are older, you should be able to tell how much isn't used while braking. What is the problem you speak of? They are so cheap if you think it might be the problem, you should swap in some new ones.

 

[nemesis_pyros]

Problem is this: I went to a 14bff and 8lug 10 bolt. Now when I step on the brakes the pedal goes almost to the floor at with point the back brakes lock up. If I pinch the rear rubber line the pedal is firm and the front brakes work fine.

What i've Replaced: Front rubber lines, pads, calipers. Rear Shoes and Wheel Cylinders. Swapped out the prop valve for a known working one. Put in an adjustable prop valve on the rear hard line. Brand new master cylinder properly bench bled. Everything has been changed out except the hard lines them selves.

I suspect now it either still air in the rear lines after the rubber line or the wheel cylinder pistons have to travel too far to engage the pads. Thats why i was asking about the "plungers" (is that what they are called?). Where would i find these and what would the part number be?

 

[dremu]

Sounds like air, or possibly a stretchy *rear* rubber line -- you didn't say, that I saw, that you replaced it. The plungers are not a wear item, IIRC, so would not be easily found at a parts house.

One other thing springs to mind, as it were: Have you adjusted the star adjuster? If not, your shoes may be not be contacting the drums until the very end of their travel, which could cause some of your problems (though it still sounds like air or a leak.)

Anyway, the idea is that you adjust the ratcheting adjuster at the bottom until the shoes almost contact the drum when you put it on, i.e. it has a veeeeeery slight drag to it. They are supposed to be self-adjusting, when you back the truck up, or if you do the procedure in the service manual about driving backward and banging on the brakes, but they get rusted up easily and never seem to self-adjust.

-- A

 

[nemesis_pyros]

We have checked all the rubber lines they don't appear to be bulging or stretching. I have set the adjusters as you mentioned. I even tried setting the adjusters very tight but It made no difference. I'm asking about the plungers because I want to make sure i have the right ones. I was thinking maybe the PO mixed up some parts and put the wrong ones in?

I have bled the brakes many times with out any change. I have just received my speedy bleeders and I'm going to put another bottle of brake fluid through the system but i just don't see that helping. I've also checked all fittings for leaks and see none. You can see my other post here : http://coloradok5.com/forums/showthread.php?t=184876