Tech Corner

Other Caliper Designs

For other caliper designs, consult manufacturer’s instructions.

Remove the caliper from the suspension knuckle (if it was not completely removed during step 3), taking care not to damage the flexible brake hose. Secure the caliper to the vehicle, in a convenient position that does not put undue stress on the brake hose.

Inspect the condition of the used pads. If the pads show uneven wear, the caliper may need to be overhauled or replaced. Refer to local regulations for disposal of used brake pads.

Inspect the condition of the caliper. Ensure all dust boots, caps and seals are in good condition, and that sliding surfaces are not damaged. For sliding calipers, lubricate the slide pins and ensure they are straight, in good condition, and allow the caliper to slide freely.

Check that the brake hose is in good condition. Replace any component that shows signs of damage or deterioration.

If the caliper uses a stepped piston design, ensure the orientation of the step is correct according to the manufacturer’s instructions.

Rotors should be machined if they are to be re-used. Use a micrometer to measure the thickness of the rotor at several radii across the face. The minimum thickness is marked on the rotor. If a rotor is under minimum thickness (or will be under minimum thickness after machining), or if it is tapered, replace the pair of rotors.

If on-vehicle machining is not possible, of if the rotor is to be replaced, remove the brake rotor from the vehicle following the manufacturer’s instructions. If wheel bearings are integral to the rotor and are to be replaced, it should be done before machining.

Machine the rotor using the slowest feed rate. Do not take heavy cuts. The final cut should be very light to minimise grooving of the braking surface.

After machining, finish both braking surfaces of the rotor with 240 grit emery to obtain a smooth non-directional surface finish. Clean the rotor with Brake and Parts Cleaner. If the rotor was removed from the vehicle, re-fit the rotor following the manufacturer’s instructions.

Use a dial gauge to measure installed rotor run-out. If the rotor is the type that is located and held in place by the wheel, use the wheel nuts to temporarily locate the rotor on the hub.

Installed rotor run-out should not exceed 100µm (0.1mm). If acceptable run-out can not be achieved, further investigation is required. The rotor, hub or suspension components may be damaged.

Mount the anchor bracket (for sliding calipers) or the caliper body (for opposed-piston calipers) on the suspension knuckle. Tighten the bolts to the manufacturer’s recommended torque. Note: if the caliper requires pads to be fitted before caliper installation, complete steps 10-11 before mounting the caliper.

Clamp the brake hose and open the bleed screw on the caliper. Use a bleed hose to catch excess brake fluid in a suitable container as you push the pistons back into the caliper. Pistons should be pushed back by hand or using a piston retraction tool. Ensure all pistons can move without binding. Take care not to expose skin, clothing or paintwork to brake fluid.

Calipers with an integral park brake often require an alternate method to retract the piston. Consult the manufacturer’s instructions.

Fit the new brake pads to the caliper body or anchor bracket and reassemble the caliper. For sliding calipers, fasten the caliper body to the anchor bracket and tighten all bolts to the manufacturer’s recommended torque. Ensure all clips, pins etc. are correctly installed.

Complete pad change and inspection of all brakes.

Flush and replace the brake fluid, unless service records show that it has been replaced within the last 12 months. Brake fluid should be flushed and replaced at least once every two years, as it absorbs water from the atmosphere which reduces it’s performance. Refer to the vehicle manufacturer’s recommendation for the correct specification of brake fluid.

To avoid contamination of the brake fluid, clean the master cylinder reservoir with Brake and Parts Cleaner before opening. Add new brake fluid to the reservoir as required, from a fresh sealed container. Flush new brake fluid through the entire brake system, starting at the wheel furthest from the master cylinder. Collect the used brake fluid in a suitable container. Refer to local regulations for disposal of used brake fluid.

Bleed the brakes following the manufacturer’s recommended procedure, paying attention to the appropriate bleeding order.

Apply the brakes several times to set the brake pads and pistons in position. Top up the brake fluid reservoir if necessary. If the brake pedal does not feel firm under foot, repeat step 14. Attach and adjust the park brake according to the manufacturer’s instructions. Wipe rotors down again with Brake and Parts Cleaner.

Fit the wheels, lower the vehicle to the ground and tighten the wheel nuts to the manufacturer’s recommended torque.
Test drive the vehicle to ensure correct brake operation.

Follow the appropriate bed-in procedure for the brake pads fitted.

The brake system should be inspected by a qualified mechanic at least once per year, or more often if the vehicle travels long distances or is subject to heavy duty conditions.