Brakes pedal will not stop going to the floor

[molson1006]

I keep bleeding the brakes but I can't get them to stop going to the floor. It is a nonpowered brake system and I have bled them twice. what else can I do? I have also tightened the star ajusters so they are rubbing just a little. help

 

[BwoncoHowie]

If you have no loss of brake fluid and your pedal leaks down repeatedly, you may have a bad primary cup in your master cylinder. I have successfully replaced seals in the master cyl but this should only be done if the bore is spotless and free of rust and imperfections. Otherwise replacement of the master cyl is in order.

BH

 

[molson1006]

Thanks, I think it must be in the mc

 

[67halfcab]

[quote author=molson1006 link=board=5;threadid=19323;start=0#msg148327 date=1056750876]
I keep bleeding the brakes but I can't get them to stop going to the floor. It is a nonpowered brake system and I have bled them twice. what else can I do? I have also tightened the star ajusters so they are rubbing just a little. help
[/quote]

Drums on all 4 or disks up front?

 

[Bluntman]

When I got my bronco, the brake pedal could be pressed to the floor and the truck would still move, and it got progressively worse. I got all my brakes replaced and now the pedal only goes half-way to the floor.

 

[74bob]

Can you pump the pedal and the brake pedal gets firmer? If you push on the pedal and hold does it slowly go down to floor? All indicate master cylinder problem. Replace the master cylinder. Cheap fix for whoa mule. ;D

 

[Bluntman]

That's exactly what mine did before i replaced the brakes, I would have to pump it to get it to stop, and usually it would end up getting firmer and wouldn't go to the floor.

 

[75Sport]

replaced the brakes? which parts? I have to pump and my master cylinder is less than a year old.

 

[67halfcab]

[quote author=75Sport link=board=5;threadid=19323;start=0#msg148577 date=1056841379]
replaced the brakes? which parts? I have to pump and my master cylinder is less than a year old.
[/quote]

I have a Brand new MC which was properly bench bleed and still had to pump my brakes to get them to work. It didn't matter how many time I bleed them it never got any better. I also had new calipers up front.

What I had to do was remove the caliper and w/the bleeder open I took a C-clamp and compressed the piston in the caliper. I was shocked at how much air was trapped inside the caliper even after bleeding it as much as I did.

I think there is still some air in the system somewhere but now I at least get full brakes at about 3/4 pedal. I expect once I get all the air out and my pedal should only go about 1/2 way. I also changed from the stock 1" bore MC to a 1 1/4" MC which helped out.

 

[Zaktly]

Hey Guys.... Just a quick one here. You guys are right on the money with replacing the master cylinder. And for some of you other first time Bronco owners out there. If you still have drum brakes you might as well go ahead and spring for the extra $10 per wheel and replace the wheel cylinders since you are already deep into brake fluid.

Just a thought... good luck

 

[Zaktly]

One more thing..... Those were wheel cylinder rebuild kids. Remember to look for pitting inside or you will just have to do it again .

 

[67EB_in_619]

IF you recently replaced the MC... or had it out.. make sure you bench bled it.. that gremlin got me good once..
good luck!

 

[Cavalry]

Kinda obvious but if 4 wheel drum are the drums adjusted properly? That too would give you a lousy pedal