Brake Booster

[buck_hunter]

Hey just wondering if anybody out there knows of a way to test the brake booster? I got no pressure behind my brake pedal in the mid range of the pedal but once i get to the bottom of the pedal it stops pretty good. Just put new front pads on and rebuilt the whole rear, new cylinders, spring kit, and shoes. and bled everything down. any suggestions would be nice.

[Blue88Comanche]

is there a leak in the brake lines somewhere? does the BB have any rust on it? might have rusted through like my old one did.

[buck_hunter]

i just fixed one brake line on the drivers side that was bad but no evidence of any other leaks. Also the booster is in good condition, i didnt know if i could take the vaccuum hose off it and maybe plug it with my finger and see if that does anything. idk :???:

[Blue88Comanche]

the booster's diaphragm could be worn out. Now would be as good time as any to upgrade to a WJ BB. its real easy and here is a link to a DIY that Comanche Country made.

[Blue88Comanche]

might to see if the vac. hose is clogged and if the hose connector on the booster is working properly

[Pete M]

do you still have the prop valve out back?

[buck_hunter]

idk lol kinda new to all this, but it is a 87 pioneer I'm almost positive its all stock.

[Pete M]

it's right above the drivers side of the rear axle. 2 brake lines go in, one comes out. has s small lever on it connected to the axle.

[buck_hunter]

I'm pretty sure it does, not 100% on it but i recall seeing something similar to what you are talking about. I will check tomorrow. So if it does, will it have a tendency to cause what is happening to me?

[Pete M]

that second line going to it can be difficult to bleed if any air gets in it. not saying that's your issue, but it's something to ponder after trying the usual suspects. you probably just need to rebleed the truck. be sure to start with the furthest from the booster (back/right) and work your way closer.

 

also, double check to make sure your rears are properly adjusted so there isn't any slop.

[carnuck]

I drove my '87 for almost 2 years before finding out one of the rear lines (return to the front) was rotted off. I bypassed the rear valve to get the brakes working and that's when the fluid started squirting out. I plugged off the return line at both ends and that cured the brake problems.

[ratrapp]

did this happen before or after you worked on the brakes?most boosters when they go bad produce a very stiff pedal.

[buck_hunter]

it has been like this since i bought the truck. So i started with the front brakes and worked my way to the back. When i put all new in the rear i got a little better brakes but still not much for any pressure until you get to the end of travel. It stops pretty good just doesnt feel right, i feel like there should be more pressure than i am getting. And there is no slop in the rear as far as i can tell both adjusters work fine and adjust properly.

[deziped]

Bleed the brakes again, rear to front.

[ratrapp]

you may have either a bad master cylinder or may need new front rotors.i've fixed many vehicles where the front rotors were either too thin or so glazed over the pads never bite into the rotors and result in a sinking pedal or decreased stopping.

[buck_hunter]

alright ill go ahead and re bleed them and see if that helps out

[carnuck]

Also manually adjust the rear brakes.