Brake Work Gone Bad

Fishfam_jku

Fishfam_jku

Caught the Bug
Been a bit but can’t find my answer anywhere yet.

This weekend went ahead and replaced my Brake Booster and Master Cylinder. Stock MS leaked and ended up killing my booster diaphragm.
Things went relatively smooth. New Booster holds vacuum. The new MS was bench bled as best possible. Install seamed to go well. I knew I had some air in the lines due to a squishy pedal, not too surprising. Went through and did a standard bleed through all four corners and was able to pull air out. Pedal felt good, so I check for leaks and buttoned it up for a test drive.
Made less than 1/2 mile before my brake pedal got stiff, only 0-1” of movement. By the time I made it a mile I knew I had an issue. Very touchy brake pedal and was having to give it some gas just to keep speed. Both front rotors are dragging. Pulled into a parking lot, sure enough, both front were locked up. Not wanting to risk it, I depressurized the brakes by a quick bleed in the parking lot, which thankfully is the same lot as our local 4x4 Shop. Drove it through the parking lot and left her there.

Now my assumption it air in the ABS system but this is new area for me. I don’t have the reader capable of ABS bleed. Anyone ran into this one? Am I missing something?

Cheers
 
Son of B***h…
Think you are on it! When I assembled the new MS and Booster felt like there was some contact the last 1/8” or so. Assumed that was just setting the new oring but now I’m over here second guessing everything 😖. Back to YouTube university.

Thank you.
 
Fishfam_jku said:
Son of B***h…
Think you are on it! When I assembled the new MS and Booster felt like there was some contact the last 1/8” or so. Assumed that was just setting the new oring but now I’m over here second guessing everything 😖. Back to YouTube university.

Thank you.
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More common on older vehicles but still on some newer stuff. Do you have the old booster to measure the rod location?
 
Yeah. Still have the old booster and MS. Although both new units are aftermarket, not Mopar, so not assuming matching dimensions but it will inform the gap. I’ll put some calipers on it.
 
GP NOIR said:
Bad brake lines will do the same thing
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Someone else suggested this one. And I’ve had it happen on an older rig. It took 100s of mile to fail after a bad service. This time, to fail in just a couple miles and immediately following what I serviced seams unlikely. All the lines have less than 20k miles on them, braided stainless from Synergy.
But I will be flushing the lines again tomorrow after I adjust the booster. I’ll be on the look out for any debris resembling deteriorating rubber in the lines.
 
WJCO said:
More common on older vehicles but still on some newer stuff. Do you have the old booster to measure the rod location?
Click to expand...
You sir, I owe you a round!
Was able to grab the Jeep this morning (after a parking lot bleed) and get her home.
Pulled the MS but couldn’t get calipers in there so took a couple tries to get the gap right. After 45min had the pedal with good gap and all four corners release perfectly.
Learned something new and because of the board it wasn’t too harsh of a lesson.

Cheers
 
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