[mitmaks]

So I went to help guy with his brakes on 80 Jeep truck. The problem is that it takes forever to slow down the truck. All the pads/shoes are good (front pads were replaced), we bled system and pedal is firm. However if you try to stop it just won't stop, takes long time for it to stop.
Is master cylinder bad? I unhooked vacuum line to booster (it has power booster) and it has suction.

[stea]

Just because the booster is getting vacuum doesnt mean its good. Start the vehicle and let the vacuum build up then shut it down. Wait for a few minutes and the pull the one way valve from the booster. If good you will hear the pressure release. If not, the diaphram has gone south.

[T-bucket23]

Originally Posted by mitmaks

So I went to help guy with his brakes on 80 Jeep truck. The problem is that it takes forever to slow down the truck. All the pads/shoes are good (front pads were replaced), we bled system and pedal is firm. However if you try to stop it just won't stop, takes long time for it to stop.
Is master cylinder bad? I unhooked vacuum line to booster (it has power booster) and it has suction.

Are all the calipers free. New pads wont help if the calipers cant squeeze them. How did the old pads look. Were they worn evenly or was the inboard pad worn a lot more than the outboard pad. Uneven wear indicates a caliper that is not sliding on its pins

[mitmaks]

pads were worn evenly. If I pump up brakes with engine off and then turn it on, brake pedal does not go down a bit. I guess it is a bad booster?

[mitmaks]

Originally Posted by stea

Just because the booster is getting vacuum doesnt mean its good. Start the vehicle and let the vacuum build up then shut it down. Wait for a few minutes and the pull the one way valve from the booster. If good you will hear the pressure release. If not, the diaphram has gone south.

I was wondering if I could rebuild booster, are there kits available?

[stea]

Ive never seen a rebuild kit. A new booster should be less than $100

[LATECH]

Is brake pedal effort high? Maybe th booster isnt your problem.
First thing to do is lift the truck, apply the brakes, and make sure both systems are working. If the combination valve is shuttled, one system wont be functioning. If the front system is shut off, you lose 60% of your braking system power.
Inferior brake pads can cause a low friction co efficient, causing a very diminished stopping power, even with ample pedal application pressure and assist from booster.
If you uhook the booster ( be sure to block vacuum hose so motor doesnt stall) and the pedal is much harder to push to obtain the same stopping distance from a set speed then the booster is obviously multiplying the effort applied to the pedal.A booster can hold vacuum and leak when brake is applied resulting in loss of assist, They can also hold vacuum and not apply any multiplication of force.
If you are pretty much applying brakes as hard as you can, and the truck takes forever to stop, it could be the pads are inferior.
If the booster is bad, you should still be able to stand on the brakes and make the wheels to skid. You might try that on a dirt road and have a friend watch to see that all 4 can be locked up.That is a good way to determine that all 4 are working.

[mitmaks]

He lives on a gravel road. Pushing pedal as hard as I could it didn't lock up brakes.
I pumped up brakes and then started the truck and pedal didn't move at all, which makes me believe booster is bad.

[adantessr]

Originally Posted by mitmaks

He lives on a gravel road. Pushing pedal as hard as I could it didn't lock up brakes.
I pumped up brakes and then started the truck and pedal didn't move at all, which makes me believe booster is bad.

It sounds like the booster is bad to me also. As already mentioned, a new booster W/O master cylinder should be less than $100.oo . First though, I would make sure that the vacuum check valve on the booster is opening. Just pull it out of the booster leaving the hose attached and make sure you are pulling vacuum. Let us know.

[mitmaks]

Originally Posted by adantessr

It sounds like the booster is bad to me also. As already mentioned, a new booster W/O master cylinder should be less than $100.oo . First though, I would make sure that the vacuum check valve on the booster is opening. Just pull it out of the booster leaving the hose attached and make sure you are pulling vacuum. Let us know.

It should suck air with the engine on? I've already checked it and it was pulling air when I took it off the booster.

[adantessr]

Originally Posted by mitmaks

It should suck air with the engine on? I've already checked it and it was pulling air when I took it off the booster.

Yup. I'd replace the booster.

[mitmaks]

Booster was replaced and brakes work as they should.
I didn't know that new booster was already adjusted to spec and adjusted it to the one on the car.
Old one someone tried to "fix" by putting a piece of saran wrap to "seal" it off.
Some redneck ingenuity there...