I replaced my master cylinder last weekend thinking it was my problem to the "hard braking". It was, but only for a few days after I put on the new master cylinder and bled them a few times. Now, when I bleed them the brakes feel fine. But when I get back in to drive later, they are hard meaning you have to press hard as hell to stop. What the hell is causing this?
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Bleeding brakes every other day!!!
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exploded99
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When you are bleeding the brakes, how does the fluid squirt out of the front calipers and the rear calipers. Which axle seems bad - front or rear? You should get a pretty good shot out of a caliper when you pop a bleeder open with the pedal pressed hard.
Are you getting vacuum boost from your power brake booster? When you bleed the brakes with the engine off, the vacuum is bled off. Is the booster recovering normally?
I suspect a problem with the fronts since they are most of your braking power. When it takes that much effort, its usually trying to stop with the rears.
Are you getting vacuum boost from your power brake booster? When you bleed the brakes with the engine off, the vacuum is bled off. Is the booster recovering normally?
I suspect a problem with the fronts since they are most of your braking power. When it takes that much effort, its usually trying to stop with the rears.
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stuck caliper? You mentioned you want to sell it so everything is going to brake now
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Did you bleed the master cylinder before you installed it?
-Drew
-Drew
exploded99
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You can check your vacuum booster:
find a quiet street, hit 25 mph or so, and stop the truck.
Take it back up to 30, put it in neutral, shut the key off, pump the brakes 6 or 7 times to bleed off the vacuum. By now you'll be back down to 25, stop the truck. Is the pedal effort the same in both cases?
Pedal effort should be quite a bit more after you bleed off the vacuum and try to stop with no boost (manual brakes).
That should get you an idea of whether you are getting vacuum boost.
Assuming your pedal is firm and does not pump up under normal brake operation ( no air in system) and you have good fluid coming out of all your calipers when you pop the bleeders, I would think vacuum booster as well. Don't forget to check the booster check valve!
find a quiet street, hit 25 mph or so, and stop the truck.
Take it back up to 30, put it in neutral, shut the key off, pump the brakes 6 or 7 times to bleed off the vacuum. By now you'll be back down to 25, stop the truck. Is the pedal effort the same in both cases?
Pedal effort should be quite a bit more after you bleed off the vacuum and try to stop with no boost (manual brakes).
That should get you an idea of whether you are getting vacuum boost.
Assuming your pedal is firm and does not pump up under normal brake operation ( no air in system) and you have good fluid coming out of all your calipers when you pop the bleeders, I would think vacuum booster as well. Don't forget to check the booster check valve!
Runnin'OnEmpty
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Good advice from Exploded; it sounds like a bad booster to me, too. Another way to check is to listen from under the dash while in park and idleing. Press on the brake pedal with your hand, and listen for a vacuum leak (with your head under the dash). If you hear a hisss, then suspect a bad booster or a snake is loose in your interior. 
Sometimes a booster won't show any leaks, but will still be bad. I guess the mechanism 'sticks' inside from wear or a leaking MC, or whatever. The only solution is to replace it.....
Sometimes a booster won't show any leaks, but will still be bad. I guess the mechanism 'sticks' inside from wear or a leaking MC, or whatever. The only solution is to replace it.....
exploded99
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The valve is in the hose between the brake booster and the intake manifold. Take it out and inspect. It allows air flow TO the intake manifold, not the other way. Make sure it opens / closes freely and air only goes one way. And pay attention when you put it back in!
You said BOOST gauge - is this thing turboed? Boost pressure is pretty hard on Ford stock check valves. You have not complained of vacuum leaks from under the dash or hood, or whoosh noises when you hit the brake pedal (all indications of brake booster failure) , so I was thinking it was just a chance that the valve was stuck shut. If you are turboed, much higher chance.
Oh, he**, I just looked at the link for 14 second explorer. Supercharged! Ya, you may have very well pounded the brake check valve shut with boost.
What did you do to the drivetrain to handle the power? I would think you would snap stock Ford tranny input shafts and toast transfer cases for breakfast!
You said BOOST gauge - is this thing turboed? Boost pressure is pretty hard on Ford stock check valves. You have not complained of vacuum leaks from under the dash or hood, or whoosh noises when you hit the brake pedal (all indications of brake booster failure) , so I was thinking it was just a chance that the valve was stuck shut. If you are turboed, much higher chance.
Oh, he**, I just looked at the link for 14 second explorer. Supercharged! Ya, you may have very well pounded the brake check valve shut with boost.
What did you do to the drivetrain to handle the power? I would think you would snap stock Ford tranny input shafts and toast transfer cases for breakfast!
exploded99
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Well, just out of curiosity let us know what you found out!
exploded99 said:
I took it to Ford, and two techs checked it out and said they were fine. I argued and they said I may have put the wrong pads on. I said whatever, grabbed my keys and left. I'm not worried, it won't be mine much longer.
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