SERVICE INSTRUCTIONS FOR THE REMOVAL AND INSTALLATION OF DISC BRAKE PADS FOR VEHICULES UP TO 3.5 TONS
Brake pads are part of the vehicle braking system, and as such are safety critical components. Therefore when changing the pads all work must be carried out with the utmost care and attention. It is recommended that brake pads should only be replaced by persons possessing the necessary expertise, i.e. a suitably trained vehicle technician. Responsibility cannot be held for any damage caused by incorrect fitment. These fitting instructions are for guideline purposes only, and do not take into consideration any special features which may apply to different type of braking systems. Any specialized instructions issued by the vehicle or brake manufacturer must be strictly adhered to with reference to the appropriate vehicle manufacturer workshop manual. To avoid brake pull and to ensure balanced braking it is important to replace the pads in complete axle sets.
With the vehicle standing on firm level ground and handbrake fully applied slacken each wheel nut on the appropriate road wheel a fraction of a turn. Chock the wheels not being worked on, jack up the vehicle and ensure its stability by using axle stands. Remove the road wheel. Thoroughly clean the outer surface of the caliper body using methylated spirit or clean brake fluid prior to pad removal. A wire brush can be used to remove excessive road dirt. Depending on the design disconnect any electrical connections (wear indicators) and remove the split spins / retaining pins and spring clips from the caliper. Using pliers extract the brake pads along with any anti-squeal shims, if fitted, carefully noting their position to ensure correct replacement. Examine the condition of the spring clips and if worn or damage fit new ones on reassembly.
- Cleaning and inspection:
Thoroughly clean the pads abutment areas using methylated spirit or clean brake fluid avoiding damage to the dust covers, clamping rings and guiding parts. Where caliper pistons are not fitted with prospective rubber boots it is essential to clean ine exposed surfaces before they are pushed back into the caliper, prior to fitting the new pads. Carefully examine the exposed surface finish of the pistons for corrosion and damage, replace if necessary. If a piston is seized the only satisfactory remedy is renewal of the complete caliper assembly. Lightly smear the piston/s with silicone grease before pushing them carefully back into the caliper bore/s. Ideally a piston retraction clamp should be used for this operation otherwise press back with a suitable flat lever. During this operation brake fluid will be displaced. Therefore, to prevent the brake master cylinder reservoir overflowing open the relevant bleed screw/s on the caliper to release the fluid from behind the piston/s via a plastic bleed tube into a suitable receptacle. When piston/s are fully back into the caliper bore/s retighten the bleed screw/s. A rust build up the outside edge of the brake disc, sufficient to prevent correct seating of the new pads may be carefully removed with a fine file.
Lightly smear anti-seize copper grease on the back and edges of the new brake pad backplates carefully avoiding the friction material and the caliper abutment slot. Insert the new pads and anti-squeal shims, if fitted, into the caliper and secure in position ideally using new split pins / retaining pins and spring clips. Reconnect any electrical connections (wear indicators) as applicable. Repeat the whole procedure on the opposite brake assembly.
- Function test:
Having refitted the road wheels and lowered the vehicle gently to the ground, firmly depress the brake pedal several application to enable the new pads to adopt their correct running clearance to brake discs. Check the brake fluid level in the fluid reservoir and replenish to maximum filling line, if necessary, using only new brake fluid as recommended by the vehicle manufacturer. CAUTION: If inappropriately handled, brake fluid may cause serious injury or damage. Observe the brake fluid manufacturer instructions.
After fitting new brake pads care must be taken when braking. Brake performance may be reduced during the bedding in period. Avoid emergency braking for the first 320 km (200m) until the pad is fully bedded in. Brake pads should be visibly checked periodically. Always fit new pads when the lining thickness has worn to 3mm (1/8”).