Break pedal travel

[jay1028]

A few months ago, I replaced the aging front brake hoses and still noticed the soft brake pedal. Just replaced the rear brake hoses and no change. With the motor running, the braking is good enough to normally stop, but with prolonged pedal pressure, it eventually goes to the floor after a minute. I can hear a whooshing sound every time the pedal is depressed. With the motor off, and resting for five minutes, I can get two good pedal presses before the vacuum is gone. Then with constant pressure on the pedal, it goes within an inch and a half to the floor. I can't remember how long I have been hearing the whooshing sound because the rear wheel bearings have been drowning out all sounds until I just got them replaced.

Master cycilnder or vacuum booster?

 

[koda2000]

Either master cylinder has an internal seal leak or there might be air in the system. The booster may cause noise, or cause a hard pedal, but it has nothing to do with pedal height.

BTW: If you've gotten air in the ABS system it can be difficult to bleed out.

 

[jay1028]

Installed new MC this morning. Pedal still acts the same. Got the MC from Autozone and it came with the bench bleed tubing and fittings. Nice. Funny, but really not funny that when the dealer replaced the rear brake hoses and cross over line, they should have noticed and told me about the problem pedal travel. Maybe they didn't do a good bleed. I will bleed all tomorrow and report back.

Not concerned about the whooshing from booster. It works or pedal would be hard. Don't get why you can pump up the pedal with motor off, but when motor is on, pedal eventually goes almost to floor.

When removed MC, no leaking was found.

MC has never been empty or removed, so can't see why air would be in ABS.

 

[swshawaii]

Any chance either the front or rear calipers were removed and the sides were switched?

Common mistake, impossible to bleed all the air without having the bleeder screws on top.

 

[jay1028]

No chance. I'm the only one that has ever serviced the brakes until I just had the rear hoses replaced. They were still functional but after all these years, I wanted them done as I had already done the front hoses. I thought maybe all the hoses could have been the problem, but now I know that they were not. And now I know it wasn't the MC.

 

[shadowless127]

I have a somewhat soft pedal, too. Never was able to figure it out and have just lived with it after I had calipers replaced, and system bled and flushed multiple times.

 

[jay1028]

Flushed through an entire quart of brake fluid and some fine bubbles came from the right rear. All other wheels were clear of bubbles. Pedal is now about two inches from floor. Went out on a dirt road and locked up the brakes and you could hear and feel the ABS come on. In all these years, I never did that before. So for now, I wish the pedal was higher but maybe it never was. When you drive two different cars, you can lose track and your mind plays games on you of what is was like before you did the work. I do remember that the pedal was never rock hard like my other vehicle, but it stops fine and you can't even hear the vacuum booster when you are driving. Funny how you can imagine things that could be wrong.

 

[koda2000]

Flushed through an entire quart of brake fluid and some fine bubbles came from the right rear. All other wheels were clear of bubbles. Pedal is now about two inches from floor. Went out on a dirt road and locked up the brakes and you could hear and feel the ABS come on. In all these years, I never did that before. So for now, I wish the pedal was higher but maybe it never was. When you drive two different cars, you can lose track and your mind plays games on you of what is was like before you did the work. I do remember that the pedal was never rock hard like my other vehicle, but it stops fine and you can't even hear the vacuum booster when you are driving. Funny how you can imagine things that could be wrong.

There's probably still a little air trapped in the ABS system. Pre-ABS bleeding techniques do not work very well with ABS systems. You need to be able to run the ABS pump while bleeding in order to get all the air out. I've read here about activating the ABS system by basically doing what you did on that dirt road, but even if the air is expelled from the ABS pump, it's still in the system and will lead to a soft/low pedal feel. Ford and brake shops have the equipment it takes to get the air out.