How do you depress the brake caliper on 06 s type jaguar

most likely they control mechanism is a bit stiff/dry , if the roof will move forward spray wd40 up each side runners etc go back and forwards a bit at a time ,this should lubricate the mechanism and hope fully save ypou having the roof stripped out to solve the problem

one of the pistons in the brake master cylinder is poss stuck at the bottom of its stroke or the return spring has broken, dont take any chances with brakes change that master cylinder

Hello and welcome to FixYa!

As a first course of action, I strongly suggest that you check the brake fluid. If it's not sitting on the right level please do fill it up.

The problem can be on the brake booster too... If it's worn out the brake tends to be hard. If that's the case then you will need to have it replaced.

Do you hear any squeaking sound from the wheels? If there is then the brake calipers can be stuck which can cause the pedal to be hard when depressed. You will need to replace the calipers if that's the case.

Hope this helps and thank you for using FixYa! Have a good one!

If your car has antilock brakes, changing the pads is a bit different than what most people are used to. With a normal (non-ABS) car, you just unbolt the caliper, press apart the old pads to retract the piston, then replace the pads. This procedure forces much of the brake fluid out of the caliper and back into the master cylinder. The fluid is put back once you step on the brakes.

With an ABS car, you CAN'T force the fluid back; if you do you'll damage the ABS valve body (£800). Instead, you must open the caliper bleed screw and drain the excess fluid out of the caliper while you press the piston back into the bore. This is very important! If you force the dirty, water-contaminated fluid back through the relatively fragile valve body, you'll ruin it.

Also, did you know that you are supposed to replace all of the brake fluid in an ABS car once each year? That's different from older-style cars too.

If it's like the 2003 The left-hand brake caliper piston retracts counter clockwise and the right-hand retracts clockwise.

Go change it at a auto place or you can buy the brake and do by yourself

If you are replacing the rear pads and are trying to retract the caliper pistons here is what you need to do.
Use a piston installation tool in order to twist the brake caliper piston into the brake caliper bore.
If you do not have the tool you can retract the piston by using a needle nose plier.
Exert downward force and rotate clockwise until the piston bottoms out.
Before installing be sure the two "U" shaped slots are at 6:00 and 12:00 Oclock.

Sounds like the pistons bound up in the calipers. Remove the calipers and attempt to seat the pistons in the calipers with a screw clamp. If no go, that's the problem. They can be replaced, but most folks just get a whole new caliper these days.

I know that it's a jag, and I know you are trying to be perfect, but in over thirty years, I've never seen a tech put a torque wrench on a caliper bolt. If you really want to I'd use about 35-40 foot pounds. (I go by bolt diameter) You don't have to slam them down but you don't want them to back out either. A bit over 35 is reasonable and should not damage anything and will keep them secure!
I have no idea what nm conversion is..

the pistons have to be screwed back in place,I use a pair of needle nose plyers while applying constant pressure to piston.They can be rotated both left & right but you will notice soon which way pushes them in.