Front Brake Pads
2. Just before the wheel(s) clear the ground, slightly release the 5 wheel
nuts otherwise removal will prove difficult with the wheel in the air.
3. With the car safely supported on jack stands, proceed to remove the wheel
nuts & wheel. Alloy wheels will fall onto the spokes if left to roll.
6. The Caliper guide bolt is chromed and should be lubricated with a
high temp grease (copper antiseize). If the chrome is heavily peeled
and brakes are wearing unevenly the guide bolt should be replaced.
Unless the caliper can slide freely braking will be on one side of
the brake rotor only which will reduce breaking performance considerably.
7. Swing the calliper up & out of the way. You will see two wide V-springs
(wire based) and guide plates (convoluted metal clip). The two act as
kick-back springs against the brake pads.
8. Brake pads themselves snap into the Guide Plates, first remove
the V-springs and the pads should unclip with light levering. Remove
the outer & inner shims from each pad, noting their order & orientation
onto the pegs on the rear of the brake pads. Re-use the shims if there
are none with new brake pads, or obtain new from the dealer.
9. Place a thin coating of copper antiseize grease between each of the
shims and the brake pad, taking care not to get any on the rotor or brake
pad surface. This avoids brake squeal and rattle.
10. Before fitting the new brake pads the FRONT calliper piston must be
pushed back into the caliper sufficiently. (On the REAR the pistons
must never be pushed back, they are wound back by a allen-bolt
itself hidden under a hex-bolt at the rear of the caliper in line
with the brake piston itself).
Before proceeding, ascertain how much brake fluid is in the reservoir
relative to the wear on the pads. If the pads are very worn, and the
reservoir is full then pushing the pistons back in will cause the
reservoir to overflow onto the body work of the car. Syphoning some
brake fluid out, then later replacing and washing the area down
liberally is required.
11. Taking the C-Clamp and a piece of wood, or a proper brake-piston-retractor,
push the piston back into the caliper. The piston must be pushed back
parallel with it's bore or damage to both will result. The seal on the
piston must not be damaged either. Snap the brake pads into the caliper,
and replace the V-springs. Ensure the pads are seated fully and the
shims haven't slipped (hence the anti-seize grease to assist).
12. Swing the caliper & brake-pad assembly back onto the rotor, ensuring
the pads will pass the rotor edge. Then refit & tighten the caliper guide
bolt to 44-49Nm, 33-36lb/ft.
13. On completing the pad change, verify the master cylinder is at the
appropriate full mark with fresh DOT3 or DOT4 brake fluid.
See the Brake Bleeding & Brake Fluid Change section
for the method.
Last Upload: 18th March, 2002. V1.50a
Tools Required
Wheel removal sockets (19mm or 21mm), breaker bar, 14mm socket, 7mm allen key,
wide screwdriver, C-Clamp & thin piece of wood, torque wrench, copper high-temp
antiseize grease or similar. Front brake pads. Hydraulic jack and U-top jack stands.
Brake Pad Min Thickness
The replacement thickness of front brake pads is 1mm, replace pads across
an axle. Caliper's outer face contains a square cut pad inspection window.
Front Brake Pads
Stock brake pads provide effective stopping distances, however there are
alternatives offering less dust (Axxiss Metal Master) or better performance (Carbon
or Kevlar brake pads). Racing pads should not be used on the street because initial
braking or emergency braking performance will be impeded.
Jack up car & remove wheel(s)
1. Ensure the handbrake is firmly applied, the car is level and in Gear/Park.
Jack up the front of car using a proper hydraulic jack & support on jack
stands at the proper Jacking & Support Points.
Removing pads from brake callipers
4. Locate the lower caliper guide bolt, its end is capped in a small
black plastic cylinder. The caliper hinges about the upper guide bolt.
A 14mm socket or 7mm allen key is required to them remove the bolt
Bleeding brakes
14. The brakes should now be bled to eliminate any air or moisture which
has got into the system, and indeed they should be bled annually anyway.
Caliper guide bolt torque: 44-49Nm, 33-36lb/ft.
Finishing Off
15. Refit caliper guide bolt cover and wheel, putting a small amount of
copper antiseize grease on the hub-wheel interface. Retorque wheel
lug-nuts in a 1-3-5-2-4 pattern first to 50lb/ft then 80lb/ft to
ensure even tightening & reduce chance of rotor warpage/wheel vibration.
Wheel torque: 80lb/ft.
URL: http://homepage.ntlworld.com/dorothy.bradbury/probemx/m_p4.htm