Removing and Installing Rear PCCB Brake Pads
WM 463520 Removing and installing rear PCCB brake padsTools
Preliminary work
1. Remove wheel.
Removing rear brake pads - PCCB brakes
The brake caliper must be removed in order to remove the brake pads. Do not open the brake hydraulic system while doing this!
Before removing the brake pads, a small amount of brake fluid must generally be removed by suction (from the reservoir). This depends on the brake fluid level and the amount of wear on the brake pads.
Brake fluid level
1. Remove warning contact wire at the brake caliper and expanding spring -arrows-. Remove warning contacts from brake pads -arrows-.
Remove brake caliper at the wheel carrier (fastening screws -1- ). Do not open the brake hydraulic system while doing this!
To remove the brake pads, place the brake caliper in a suitable place (e.g. on a hydraulic lift.).
Rear brake caliper
2. Pull the brake pads -1- out of the brake-pad guide pins -2-.
Removing brake pads
Generally, the brake piston damping plates (claw plates in the brake pistons) are also removed at the same time (if they are still fitted). If this is not the case, remove the brake piston damping plates (claw plates in the brake pistons) separately.
Brake piston damping plates (claw plates in the brake pistons)
3. Remove expanding spring on the brake caliper -arrows-.
Expanding spring
Installing rear brake pads - PCCB brakes
Information
The expanding spring, brake piston damping plates and brake caliper fastening screws must be replaced whenever the brake pads are changed.
When fitting the disc brake pads, ensure that the brake piston damping plates are bonded securely to the brake pad back plates.
1. Before fitting the brake pads, check the brake discs for wear. For details of minimum brake disc thickness, see -4600TW Technical data/Brake wear limit.
2. Push the brake pistons back into their original position using the brake piston resetting fixture NR.144.
3. Fit new expanding spring on the brake caliper.
Expanding spring
4. Fit new brake piston damping plates in the pistons and the brake pads.
Fitting brake pads
Individual brake piston damping plates are used in PCCB brakes (status as at June 2006). It is important here that the brake piston damping plates are seated perfectly in the brake pistons and are bonded securely to the brake pad back plates.
Brake piston damping plates in brake pistons
Please observe the following when fitting brake piston damping plates and brake pads:
Insert brake piston damping plates - with protective film - into the pistons.
Clean the backs of the brake pads by giving them a quick wipe with a suitable solvent (to remove any dust and grease).
Pull off protective film completely.
Insert brake pads and press these down flat onto the bonding surface (brake piston damping plate and pads are touching the fully retracted pistons at the moment of contact). When doing this, make sure not to touch the bonding surfaces or the cleaned backs of the brake pads with your fingers.
Shortly after installing the brake caliper, the brake (brake pedal) must be pressed with average brake pressure for approx. 5 seconds to allow the brake piston damping plates and brake pads to connect securely.
When test driving the vehicle, do not brake too severely at the beginning to ensure subsequent/optimal driving comfort.
5. Fit brake caliper on wheel carrier. Use new fastening screws -1-. Tightening torque: 85 Nm (63 ftlb.).
Immediately after fitting the brake caliper, fit the brake pads on the brake discs. To do this, press the brake (brake pedal) with average brake pressure for approx. 5 seconds to allow the brake piston damping plates and brake pads to connect securely.
Then insert the warning contact wire and the warning contacts -Arrows-
Rear brake caliper
6. Check the brake fluid level and correct it if necessary. The brake fluid level must be between the MIN and MAX markings.
Brake fluid level
Bedding in the brake pads
New brake pads require a slightly longer bedding in period for PCCB brake discs than cast iron brake discs.
In general, the following applies: New brake pads must be worn in (bedding in period), their optimum braking effect is not reached until after a few hundred kilometers. The slightly reduced braking effect must be compensated for by increased pressure on the brake pedal. The same also applies after changing brake discs.
Subsequent work
1. Fit wheel.