no rear brakes

[raymos]

i need some help diagnosing why my rear brakes are not working correctly. the first time i noticed it was a couple of years ago my dad had to tow me out of a ditch on an icy hyw. and when he stopped i rear ended him and he said the fronts were locked and the rears were still pushing the truck. that was when i was 1/2 ton, when i swapped the 14bff a couple of years ago it got new shoes, hardware, and wheel cylenders. i also replaced the master cyl. a couple of years ago.

i did a search but didnt really find anything, so where do i start?

 

[ChrisPerry]

I have heard that if the proportioning valve sticks that you won't get pressure to the rears. Have you tried resetting it? I think they have a button on the side, maybe covered by a rubber plug.

 

[michael0584]

When you bled the rear brakes did you get pressure and fluid? Have you jacked up the rear end and put it in gear and see if the rear brakes will hold?

 

[496truck]

Are the rear brakes adjusted properly? This is probably the most common reason for drum brakes not working properly.

 

[raymos]

I have heard that if the proportioning valve sticks that you won't get pressure to the rears. Have you tried resetting it? I think they have a button on the side, maybe covered by a rubber plug.

ill look into that

When you bled the rear brakes did you get pressure and fluid? Have you jacked up the rear end and put it in gear and see if the rear brakes will hold?

i dont remember its been a long time since i bled them. and no never jacked up the rear (i dont even think i have a floor jack thats up to the task )

Are the rear brakes adjusted properly? This is probably the most common reason for drum brakes not working properly

could be the problem. just need to turn the adjuster? how do you know when its adjusted properly?

 

[badmix]

Id say proportion valve as well. Shop that redid my lines after I screwed them up said it was a bitch to get it unstuck, lol. Im guessing some HARD braking or something like that is what is needed to unstuck them, dunno.

 

[k20]

I replaced my prop valve, found a new one on ebay for 30 bucks or so. Just peace of mind that it isnt stuck in a bunch of rust or something. Anyway, the GM manual says to tighten the rears down til you can barely turn them then back them off 33 clicks. As I recall on mine I set the parking brake 4 or 5 clicks down, tightened the adjusters til I couldnt turn them anymore, let the ebrake off and tightened em down 2 or 3 more clicks. Checked, ebrake was good and the brakes were high and tight.

Does your pedal seem pretty low to the floor? If so Id almost bet that the adjustment is the problem.

 

[raymos]

ya i got a brand new prop. valve for 33 buck a wyle back and i was just gonna put it on cause i have it. its been a wyle since i drove the truck but i think the pedal went down prety far, so i will try to re adjust the brakes im also gonna bleed them again.

 

[K5dreamer]

OH OH OH I LOVE setting the adjuster on drum brakes.


find a BIG EMPTY parking lot. put truck in reverse with lots of space behind you. step on gas, drive backwards to about 25mph... slam on brakes

of course, this is only advisable if everything else is in working order. if youve got a hydraulic line problem or some other issue, this could lead to a wreck.

 

[k20]

And that only works if the adjusters arent frozen up.

 

[xCaliK5x]

I will keep an eye on this, since mine stopped working again........ my experience was this, hope it helps.

My rear brakes were inop as I found out on the smog dyno I could STAND on the pedal, nothing.

My proportioning valve was stuck blocking the rear. I could find no "Reset" button but an old GM tech told me to do this:

I put on a power bleeder and opened all four bleeders and pumped the brakes.

The valve recentered and the "Brake" warning lamp went off.

Rear 14BFF drums were working great.

Now a few weeks later, they stopped working again but will still stop if you stand on the pedal, not like before. No brake light. I'm wondering if this is adjusting?