Rear Brake Pad - Premature Wear Within 3000 miles

91jaguar05

70-18


Brakes - Premature Rear Pad Wear - Repair

MODEL 89 MY - onwards XJS DATE 9/91


ISSUE:

Premature REAR brake pad wear (in less than 3000 miles) is due to the brake pedal sticking and applying continuous low pressure to the rear calipers.


Brake pedal sticking can be caused by over-tightening the pivot bolt or incorrect setting of the brake light switch.

ACTION:

1. Loosen the nut for the brake pedal pivot bolt 1/2 turn.

2. Reset the brake light switch as follows:

^ Loosen the switch and adjust switch position so that when the plunger is fully pressed in, there is at least .025~ clearance between the plunger and brake pedal.

^ Inspect the rear discs for excessive wear and calipers for possible heat damage. Replace components if necessary.


SYSTEM OPERATION:

^ The initial movement of thc brake pedal (3/16" travel) applies 2 bar (29 psi) pressure to the rear brakes only.

^ The pressure delay valve (located on the L/H inner fender on 89-91 MY vehicles and on the R/H inner fender on 92 MY vehicles) then holds this pressure until the front brake line pressure has reached 8 bar (116 psi).

^ When the front brake line pressure reaches 8 bar with continued load on the brake pedal, the pressure delay valve opens and increasing pressure is then applied to both front and rear brakes.


WARRANTY INFORMATION:

Fault Code: 7EC
Repair Operation Number: 86.65.56 (Setting brake light switch)
Time Allowance: 0.10 hrs.