I was told everytime the main pads are changed even if there is material left. Is that true?

 

Apart from those cars fitted with Brembo brakes, there are no separate parking brake pads on X350 rear brakes.

Jaguars up to the XJ Series 1,2 and 3 have separate pads, plus the XJS cars with inboard rear brakes. Later XJSs have outboard brakes, but whether these have separate park brake pads I don't know, or what the XJ40 and X300/308s have.

 

I guess at this point it does not really matter, as I have gone ahead and purchased a set. But it would still be interesting to know the answer...

 

So you have Brembo brakes then.

AFAIK Jaguar themselves have never recommended park brake pads at every change of main brake pads. Park brake pads should last a long time, as they are only used to hold the car when it is stationary, and only very, very, rarely used to slow the car down.

One of those rare times I once used the park brake (handbrake in the UK), to stop my rear wheels from slipping when I was driving a '76 Rover 3500 on snow. This car didn't have a limited-slip diff. I just applied the handbrake a small amount. It seemed to work at the time.

 

I have a 2005 Jaguar XJR which has the Brembo brakes. This system also has separate parking brakes and these wear out quickly on my car.
I could not understand this because I thought that they only held the rear brake only when parked.
I was informedby a Jaguar dealer that this system uses the rear electronic parking brake as part of the traction control system and actually applies the parking brakes while in motion as part of this system.
This is the only reason that makes sense to me for these brake pads to wear out so quickly.
Does anyone know if this is in fact true?

 

AFAIK your dealer is wrong; the main brake is used as it is easily switcheable via the ABS control block. Park brake is too slow acting. However, the park brake can lose its calibration thus causing a small drag on the3 disc, (unnoticed in normal driving), which wears them out prematurely.

 

The x308s have separate pads but not on the disc like the x350s...they are on the inside of the rear wheel

 

I'm looking at a Super that has frozen calipers and worn pads-$1000-1100ish to change out they said...

 

The calipers have a jack in them that pushes the pads out when the parking brake is activated. There are no separate pads for the parking brake. XJ 300's (96-2003) had a drum inside the brake rotor with special parking brake shoes that contacted the rotor, not pads. There is no system that uses the parking brake while the car is moving. The ABS and traction control work through the normal hydraulic system just like the foot brake does. The traction control uses the ABS motor to apply the brake for the spinning wheel which then causes the open differential to naturally apply torque to the wheel with traction through the spider gears in the center of the differential.

 

As mentioned before, all cars, including mine, that were equip'd with Brembos, have a secondary Brembo caliper for the parking brake for a total of 4 rear calipers

 

Turns out they were worn so I replaced them. Lasted 80k miles so I guess that's not too bad