Hard to push break pedal

techno1154 · Dec 5, 2013

The breaks hold well but not as good as I think they should. I have a set of the Go-jeep special that I installed just over a year ago. In my opinion, they should be better at stopping the XJ on 30" BFG AT's. I think the booster may be on its way out. There is no discernible vacuum leaks but it is more difficult to push than I remember or should be.
I want to do check to see if there is a problem with it before I go tearing into the break system. How do one go about doing that?

WB9YZU · Dec 5, 2013

techno1154 said:
The breaks hold well but not as good as I think they should. I have a set of the Go-jeep special that I installed just over a year ago. In my opinion, they should be better at stopping the XJ on 30" BFG AT's. I think the booster may be on its way out. There is no discernible vacuum leaks but it is more difficult to push than I remember or should be.
I want to do check to see if there is a problem with it before I go tearing into the break system. How do one go about doing that?

"Go-jeep special" ? OK, I give, what's that mean? Did you do a Front brake mod, Rear brake mod? Do you have a specific link to the Gojeep article that you used?

"hold well"? What do you mean? What instance are you trying to hold the Jeep in one place? With the brake pedal only, the parking brake, what?

Is the Master Cylinder Stock, or did you change that when you changed the brakes?

Has the brake pedal always been hard to push, or just since you did the "Go-jeep special"?

WB9YZU · Dec 5, 2013

Did you look at this thread?

http://www.naxja.org/forum/showthread.php?t=1091190

techno1154 · Dec 7, 2013

WB9YZU said:
"Go-jeep special" ? OK, I give, what's that mean? Did you do a Front brake mod, Rear brake mod? Do you have a specific link to the Gojeep article that you used?

"hold well"? What do you mean? What instance are you trying to hold the Jeep in one place? With the brake pedal only, the parking brake, what?

Is the Master Cylinder Stock, or did you change that when you changed the brakes?

Has the brake pedal always been hard to push, or just since you did the "Go-jeep special"?

The Go-jeep special. http://jeep-xj.info/HowtoFordBAdiscs1.htm

I bought them in 2006 and only installed them recently. I had good disks and rotors on the XJ at the time. In addition, I spent a few years in the islands while the XJ sat in the driveway.

They do hold well. I could get them (all 4 wheels) to lock up on dirt but not on pavement. The OEM brakes with premium pads would lock up on pavement.

Yes, the master cylinder is original OEM including the break booster. The XJ at this time have over 270,000 miles. Old age or high mileage may be catching up with it.

techno1154 · Dec 7, 2013

WB9YZU said:
Did you look at this thread?

http://www.naxja.org/forum/showthread.php?t=1091190

Yes, I am a where of this thread. What I want to know is how to test the break booster so I would not throw parts at it hoping that at some time the problem would mysteriously go away.

WB9YZU · Dec 7, 2013

http://www.ehow.com/how_7507543_test-brake-boosters.html

Matthew Currie · Dec 8, 2013

WB9YZU said:
http://www.ehow.com/how_7507543_test-brake-boosters.html

That's a pretty good set of checks. I'd add one more: after all the rest, turn the engine off and leave it. Come back an hour or so later. A good booster should still have vacuum. If the pedal is already fully hard it's leaking.

techno1154 · Dec 8, 2013

Matthew Currie said:
That's a pretty good set of checks. I'd add one more: after all the rest, turn the engine off and leave it. Come back an hour or so later. A good booster should still have vacuum. If the pedal is already fully hard it's leaking.

I have not done the multi-stroke test as yet but the pedal do get hard in about 30 minutes or less after the engine is stopped.

Matthew Currie · Dec 8, 2013

techno1154 said:
I have not done the multi-stroke test as yet but the pedal do get hard in about 30 minutes or less after the engine is stopped.

I would start checking further because the booster sounds suspect. Of course a little leakage can be lived with, but I've had XJ's over 250 thousand miles that would hold vacuum for a day or more. One can hope it's a valve or a line, which would be a nice cheap alternative to needing a new booster.

Hard to push break pedal

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