Causes for excessive brake pedal travel?

[harringtondav]

'99 Durango. East central IA rust bucket, but it runs well and is a solid tow vehicle.

The brake pedal travels farther than when new to grab. It holds OK with no leak down, but is a little too close to bottom for comfort. I previously replaced all rusted out brake lines, and bled them well, I think. Pumping the pedal doesn't raise the grab point.

Bad master cylinder? Bad vacuum booster? .....? The old dog is worth hanging on to for two tow trips a year.

 

[tpenfield]

I had a similar problem on my 2004 Explorer. You can Google some simple tests to see if the brake booster is working OK. On my car it turned out that the disc pads had become rusted into the caliper, so only one side of the pads was doing the braking.

I'd check the pads/calipers to see if everything is working properly.

 

[Scott Danforth]

potential causes:
air in the line somewhere
leaking master cylinder
leaking caliper or wheel cylinder

 

[Bob_VT]

potential causes:
air in the line somewhere
leaking master cylinder
leaking caliper or wheel cylinder

There is also the possibility that the driver is shrinking!!!!

I think I would look at the brake booster since you state there is rust............

 

[NYBo]

A bad brake booster will result in a hard pedal with increased pedal pressure needed to stop the vehicle.

Do you ABS on all 4 wheels or just the rears? You can't bleed the former without cycling the ABS pump, which requires an advanced scan tool.

 

[gm280]

Not knowing your setup, I would check the disks/pads in the rear for wear and look for any signs of leakage on the calibers or wheel cylinders. And the brake power booster is very easy to check. You could have a leaking master cylinder that is allowing bypass from one section to the other. And there would be no sign of any leaking fluid with that as well. Just some ideas.

 

[harringtondav]

A bad brake booster will result in a hard pedal with increased pedal pressure needed to stop the vehicle.

Do you ABS on all 4 wheels or just the rears? You can't bleed the former without cycling the ABS pump, which requires an advanced scan tool.

Front disc w/ABS in the front. Rear drums. I need to pull a drum to remove a cross threaded wheel stud. I'll see if the wear adjuster is working correctly.

 

[Grub54891]

Front disc w/ABS in the front. Rear drums. I need to pull a drum to remove a cross threaded wheel stud. I'll see if the wear adjuster is working correctly.

That's where I was going to suggest. Rear shoes hardly ever adjust themselves.

 

[rothfm]

Tad old but could led more insight. Ive done the below on several fords, and believe it applys to alot of brake boosters. But first ensure the brake system is not at fault, and everything is good.

I had vehicles were after full brake work, the pedal still was low. Google items about the Booster actuator screw.

Unbolting the booster uncovers a small acutuator screw the moves when you push the pedal. Adjusting this screw out in very small 1/4 turn increments and then testing, can raise the heigh of pedal and reduce travel when the brakes actually engage. Too far and you will drag pads.

Do a bit of research and you will find what I'm talkng about. Done it on several vehicles and like the "higher" pedal feel.

 

[harringtondav]

Tad old but could led more insight. Ive done the below on several fords, and believe it applys to alot of brake boosters. But first ensure the brake system is not at fault, and everything is good.

I had vehicles were after full brake work, the pedal still was low. Google items about the Booster actuator screw.

Unbolting the booster uncovers a small acutuator screw the moves when you push the pedal. Adjusting this screw out in very small 1/4 turn increments and then testing, can raise the heigh of pedal and reduce travel when the brakes actually engage. Too far and you will drag pads.

Do a bit of research and you will find what I'm talkng about. Done it on several vehicles and like the "higher" pedal feel.

Thanks, if I knew this, I forgot. I was about to replace the master cylinder since since there are no leaks, and no air that I can detect by 'pumping up'.

 

[dolluper]

A just your rear brakes and or un size your caliper slide bolts . Only if you have no leaks and you didn't allow your master to run dry or about dry . Booster problems usually give you rock hard pedal.