guys help.....brake issue question

[cwood]

Changing the pads on my jag xf (rear). I was having trouble getting one piston in and ended up winding it counter clockwise and it came loose but not out of the boot. I quickly realized my error and got it back in and retracted. I bled it some but now I have no pressure and it is leaking...don't know from where yet but I have no pedal firmness. Does it wreck a caliper to wind it out like that even if it goes back in?

Stranded Damn!! any suggestions welcome.

[Rich A]

You possibly damage the o-ring on the piston or housing.
You will have to rebuild the caliper or replace it.

[Mustang Man]

Behind the dust boot is a square cut o-ring that is the piston seal and helps it retract from the rotor a few thousands when you release pedal pressure. Most likely when the piston came out too far that seal went under the piston, so when the piston got screwed back in, it pushed the o-ring out of its groove, causing a fluid leak bypassing the piston...



HTH...
Mark

[joyridin']

When you say no pressure, do you mean no pressure on the brake pedal or no pressure on the pad to stop the rotor from turning?

Assuming you didn't screw up the seal when you put the piston back in, you may have to pull the ebrake quite a few times to get the piston to ratchet back out. There may not be enough travel in the piston for the pad to make contact with the rotor. Using the ebrake is how you adjust the brakes.

Either way, for the cost of a rebuild kit, I would buy one and rebuild both calipers. It takes a little time, but at least you won't have to worry about it down the road.

[cwood]

it was leaking fluid in some quantity with brake pedal push and the pedal would not firm up. I elected to swallow my pride and have the car go to the dealer.

I'm sure it won't cost much :-)

[Cobra Cory]

Yeah if it was leaking it was sucking in air every time you let off....
You have to be careful about shuttle valves in the master cylinder and ABS getting out of place too.