Can someone help. I'm in the process of installing new pads on the Brembo parking brake and can't get the "piston" to retract. I guess I need the special tool but which direction do you rotate the "piston" to retract it. Any tips on doing this and on sourcing the special tool or any suitable substitute? Thanks.

 

When you switched off the car did you hold the lever for the park brake pushed down so the park brake was off and the pads were released?

The pistons should only be wound back just enough to get new pads in, if you wind them back too far the calibration of the electric park brake will be thrown out and the handbrake will be jammed on when you restart the car.

There is actually a function in the IDS/SDD diagnostic system "park brake to service position" which winds the pistons back. As for doing it by hand, maybe check the JTIS for some instructions (sorry i don't have it with me now).

If you wind them back too far you will have problems and will need the IDS/SDD to reset the position, so be careful!

 

Thanks Cambo. I did push the park brake down so PB was released at power off. I also tried IDS/SDD "park brake to service position" but am not sure it worked. One side was easy to remove the pads the other side a real *itch. Maybe I should try IDS/SDD again to wind pistons back. Anyway just wanted to know which direction they turn to retract if anybody knows. JTIS just says use the special tool but its not clear which direction to rotate.

 

I'm not sure which way to turn them myself...

S-Type R with Brembo's and the Alcon-equipped X150 uses the same park brake caliper, maybe have a search on those models, the answer might pop up?

 

hafren,

The pistons should be turned clockwise to retract them. I turned them 1/2 rotation at a time until the new pads would fit, and I think the total rotation required was about 1-1/2 turns.

I contemplated fabricating a special tool from a flat metal bar with two properly-spaced holes threaded to accept machine screws to serve as the pins. But that would have taken 15 minutes or more.

I then contemplated removing the outer flange of the caliper (the upper section in the photo below) so I could use needle-nose pliers to turn the piston, but the screws that secured the caliper halves together were really tight and I didn't want to risk damaging the screws or stressing the brake fluid line.

Ultimately, I improvised with a pair of needle-nose Vise Grips (Mole Grips) and a couple of machine screws that fit into the holes in the piston. If you set the pliers just tight enough, you can crush the threads on the screw near the tips of the pliers enough that the wider throat of the pliers further back will be able to grip the inner screw (on the right in the photo), but on the first piston I managed to do it with the inner screw just loose in the pliers:




Cheers,

Don

 

Thanks Don you're a saviour. I'll be trying that tommrrow.

 

I should have also mentioned that once you get the new pads on and the calipers reinstalled, work the lever on the caliper repeatedly to crank the piston back out. I worked it a few dozen times before I felt like the tension on the lever changed.

 

This is all good info, I added it to the FAQ

 

Autozone has a tool loaner program that you can get the piston removal kit and use it for free. An easier solution than the plier trick.

 

I tried the autozone kit but it didn't fit the XJR Brembo caliper piston, but at least it was free.

 

Cambo, Don B,

sounds like you folks have all the answers here. For my 2004 XJR I replaced the ParkBrake pads at 60K miles. The car has Brembo brakes and the left parkbrake was worn way more than the right. Now 30K miles later the left continues to wear much quicker. I plan to remove the left park brake caliper, and clean up well as well as be sure the lever works freely as Don B states, and put a thin layer of lube on wear surfaces. I have no clue is the programming may be in error now. Any comments or thoughts?

RyeJag

 

Lost patience hunting down an AutoZone with the brake caliper tool in stock, so i purchased my own. Inexpensive, necessary and even has a left and righthand actuator.