1994 Ford Explorer XL 4WD - What could make BOTH front calipers not release?

The rotor and hub assembly is one piece and I replaced them along with everything else. The races are pressed into the hub. The bearings are held in with the seal on the inside and the bearing nut on the outside. Just fyi. This is not where the problem is.

All stainless brake lines under the hood.

Still going to try Nevada’s test at first opportunity…

Okay! I pulled the wiring harness for the ABS, just in case pulling the fuse hadn’t been enough.

Went for a warm-up-the-brakes drive. Still had the steering wheel wobble once it got warmed up.

Got home, left the engine running in case that mattered, jacked up the front right and WOW that wheel did not want to turn.

Loosened up the master cylinder nuts and, like magic, the wheel turned freely again. Just a tiny bit of friction from the pads that I assume is normal.

Now, what does this mean?!? :slight_smile: Bad power brake booster? Or could something else (vacuum related?) be making the power brake booster not release? Or like George suggests, a problem with how the pedal is interacting with the brake booster?

The pushrod between the booster and master is adjustable. Adjustment usually isn’t necessary but someone may have made a change. Check the depth of the master cylinder and the extension of the pushrod. Could be adjustable, might be the wrong master cylinder.

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It’s funny how many wrong ideas I can have in such a short period of time. Looking forward to checking the master cylinder part number and push rod depth tomorrow. Thank you!

Like they say, winner winner, chicken dinner. At least when you shorten the rod a little, you’ll have all new brake parts.

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Some OEM brake boosters and master cylinders come with a gauge to verify pushrod position. You won’t find this at the dollar auto parts store.

No part number on the MC but it looks like the part online.

Lol that gauge dimensions diagram is not to scale. I cut one out of cardboard.

Seems like just starting the engine would have the same effect as applying a vacuum pump, no?

Ok, following instructions is over. Trial and error has begun.

Wow wow wow wow wow. It’s like a new car.

I shortened the push-rod by about 1/8 inch and the brakes still worked so I took it for a drive. First I did a lot of start and stop to warm things up. Then I drove without braking for a good while (wow, I can coast lol), then stopped and took the disc temps, which were in the 100-150 range. Then I took it for the wobble test by going faster and up and down hills: no problems! Got home and checked temps again: 300 right side, 350 left (driver-side). They didn’t smell and radiate heat like they used to after this test drive.

So I would call that a success. Thank you all, but especially Nevada!

(I did notice that it has a little pull to the left when braking, more noticeable with a hard brake at high speed…)

You can do it fast or you can do it cheap . . . or you can do it my way which is just ridiculous.

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I stand corrected.

Make sure that the master cylinder has a vented cap.

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