chapter 32

CHAPTER 32

Disc Brake System

Removing and Inspecting Calipers

Research the procedure for removing the caliper in the appropriate service information. Loosen the bleeder screws slightly and then retighten them.

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Removing and Inspecting Calipers

If the caliper is being rebuilt or a new caliper will be installed, it is good practice to flush the old brake fluid from the system at this time.

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Removing and Inspecting Calipers

Use a brake pedal holding tool to slightly apply the brakes and block off the compensating ports in the master cylinder to avoid excess fluid leakage.

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Removing and Inspecting Calipers

Remove the brake line or hose from the caliper. Be careful not to lose the sealing rings.

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Removing and Inspecting Calipers

Push the caliper pistons back into their bores slightly. While many use a screwdriver as shown, a pry bar is a safer choice.

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Removing and Inspecting Calipers

Remove the caliper assembly from its mountings.

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Removing and Inspecting Calipers

Inspect the caliper for leaks or damage, including the piston dust boot. Determine any necessary actions.

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Inspecting Caliper Mountings,Slides, and Pins

Clean the caliper mountings and slides/pins using equipment/procedures for dealing with asbestos/hazardous dust.

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Inspecting Caliper Mountings,Slides, and Pins

Inspect the caliper mountings and slides/pins for wear and damage. Determine any necessary actions.

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Inspecting Brake Pads and WearIndicators

Determine the type of wear indicator system utilized. Check that it is not contacting or nearly contacting the rotor.

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Inspecting Brake Pads and WearIndicators

If the system is a sensor style, test the system to verify that the system is operational. Determine any necessary actions.

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Checking Brake Pads

Remove the pads and retaining hardware. Inspect all pads, retaining hardware, and anti-noise shims for wear or damage.

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Checking Brake Pads

Measure the remaining brake pad thickness and compare to specifications. Determine any necessary action(s).

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Disassembling Calipers

Disassemble the caliper, following the service manual procedure.

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Disassembling Calipers

Clean all of the caliper parts following the service manual procedure.

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Disassembling Calipers

Inspect each of the parts for damage, rust, and wear.

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Disassembling Calipers

Measure the caliper bore-to-piston clearance with a feeler gauge and compare to specifications. Determine any necessary actions.

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Reassembling Calipers

Make sure the rotor has been properly installed on the hub/spindle and the hub surface is free of rust or dirt.

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Reassembling Calipers

Reassemble the caliper assembly, following the manufacturer’s procedure.

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Reassembling Calipers

Assemble the pads, hardware, and caliper on the caliper mountings using the specified lubricant. Lubricate all moving parts.

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Reassembling Calipers

Reinstall the brake line fittings using two new copper washers (if equipped).

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Reassembling Calipers

Tighten the brake line fitting and caliper bolts to the proper torque. Bleed the brakes following the manufacturer’s procedure.

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Reassembling Calipers

Seat the pads by applying the brake pedal several times, not allowing the pedal to go all the way to the floor.

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Reassembling Calipers

If the brake pedal is spongy, you will need to bleed the brakes of any remaining trapped air in the system.

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Reassembling Calipers

Inspect the system for any brake fluid leaks, no matter how small.

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Retracting and Readjusting Pistonson an Integrated Parking Brake

Research the procedure for retracting the caliper piston. Select the proper adapter or tool to match the caliper piston.

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Retracting and Readjusting Pistonson an Integrated Parking Brake

Install the tool and turn it in the direction that causes the piston to retract.

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Retracting and Readjusting Pistonson an Integrated Parking Brake

Continue turning until the piston is lightly seated at the bottom of its bore.

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Retracting and Readjusting Pistonson an Integrated Parking Brake

Make sure the dust boot is seated properly in its grooves.

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Inspecting and Measuring DiscBrake Rotors

Research the procedure and specifications for inspecting the rotor. If you have not already done so, remove the caliper assembly, brake pads, and any hardware. Clean the rotor with approved asbestos removal equipment.

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Inspecting and Measuring DiscBrake Rotors

Inspect the rotor for hard spots or hot spots, scoring, cracks, and damage.

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Inspecting and Measuring DiscBrake Rotors

Measure the rotor thickness at the deepest groove or thinnest part of the rotor and compare to specifications.

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Inspecting and Measuring DiscBrake Rotors

Measure the thickness of the rotor in a minimum of five to eight places around the face of the rotor. Calculate the maximum thickness variation and compare to specifications.

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Inspecting and Measuring DiscBrake Rotors

Set up a dial indicator to measure lateral runout. Rotate the rotor and find the lowest spot on the rotor, then zero the dial indicator.

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Inspecting and Measuring DiscBrake Rotors

Slowly rotate the rotor to find the highest spot on the rotor. Read the dial indicator showing maximum runout.

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Inspecting and Measuring DiscBrake Rotors

Keep turning the rotor to make sure the dial indicator does not read below zero. If it does, rezero the dial caliper on the lowest spot. Keep turning the rotor to find the highest spot and reread the dial indicator. Compare all of your readings to the specifications and determine if the rotor is fit for service, is machinable, or needs to be replaced.

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Removing and Reinstalling Rotors

Research the procedure for removing and reinstalling the brake rotor. If you have not already done so, remove the caliper assembly, brake pads, and any hardware. If the caliper mount straddles the rotor, remove it.

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Removing and Reinstalling Rotors

To remove the hubless-style rotor, mark the rotor for proper reinstallation.

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Removing and Reinstalling Rotors

If there are screws or speed nuts holding the rotor to the hub, remove them.

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Removing and Reinstalling Rotors

Remove the rotor from the hub.

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Removing and Reinstalling Rotors

To remove the hub-style rotor, remove the wheel bearing locking mechanism.

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Removing and Reinstalling Rotors

Remove the wheel bearing adjusting nut, thrust washer, and outer bearing.

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Removing and Reinstalling Rotors

Follow the steps of the inner bearing and grease seal removal procedure if the rear bearing must be removed.

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Removing and Reinstalling Rotors

To reinstall a hubless-style rotor, clean all mounting surfaces on the hub and rotor and remove any burrs.

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Removing and Reinstalling Rotors

Slip the rotor over the wheel studs.

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Removing and Reinstalling Rotors

If the rotor uses small screws to hold the rotor to the hub, reinstall those and tighten to the proper torque.

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Removing and Reinstalling Rotors

Spin the rotor to ensure it spins true and does not contact any other components such as the dust shield.

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Removing and Reinstalling Rotors

To reinstall a hub-style rotor, see the wheel bearing service skill drills in the Wheel Bearing chapter. Be sure to properly lock the adjustment nut in place once adjustment is completed.

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Removing and Reinstalling Rotors

Spin the rotor to ensure it spins true and does not contact any other components such as the dust shield.

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Refinishing Hubless Rotors onVehicle

Research the brake lathe manufacturer’s procedure for properly refinishing the rotor. Mount the on-car brake lathe to the rotor after cleaning the rust and dirt from between the rotor and hub or adjusting the wheel bearing so there is no end play.

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Refinishing Hubless Rotors onVehicle

Perform the runout calibration on the brake lathe.

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Refinishing Hubless Rotors onVehicle

Adjust the cutting bits and cut off any lip at the edge of the rotor.

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Refinishing Hubless Rotors onVehicle

Make sure the cutting bits will not contact the rotor face, and move the cutting head toward the inner diameter of the rotor face. Set the cutting bits to the proper cutting depth for machining.

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Refinishing Hubless Rotors onVehicle

Install the anti-chatter device, if specified.

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Refinishing Hubless Rotors onVehicle

Engage the automatic feed and watch for proper machining action. If necessary, repeat this step until all damaged surface areas have been removed on both sides of the rotor.

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Refinishing Hubless Rotors onVehicle

If necessary, perform a finish cut on the rotor.

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Refinishing Hubless Rotors onVehicle

Remeasure the rotor thickness to determine if the rotor is above minimum thickness specifications.

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Refinishing Rotors off Vehicle

Research the brake lathe manufacturer’s procedure for properly refinishing the rotor. Clean nicks, burrs, or debris from the mounting surfaces of the rotor including the centering hole.

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Refinishing Rotors off Vehicle

Mount the rotor. Check that the rotor is running true on the lathe.

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Refinishing Rotors off Vehicle

Install the anti-chatter band or anti-chatter pucks on the rotor.

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Refinishing Rotors off Vehicle

Position the cutting head about one-quarter the way in from the outer diameter of the rotor. Turn on the lathe.

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Refinishing Rotors off Vehicle

Set the cutting bits to the proper cutting depth for machining the ridge.

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Refinishing Rotors off Vehicle

By hand, move the cutting head outward toward the ridge. Slowly remove the ridge.

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Refinishing Rotors off Vehicle

Once the ridge is removed, run the cutting head all the way in to the inner face of the rotor.

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Refinishing Rotors off Vehicle

Set the cutting bits to the proper cutting depth for machining the rotor face.

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Refinishing Rotors off Vehicle

Engage the automatic feed on “fast” cut and watch for proper machining action. Some single-cut machines only have one cutting speed. If necessary, repeat this step until all damaged surface areas have been removed on both sides of the rotor.

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Refinishing Rotors off Vehicle

If necessary, perform a finish cut on the rotor. This is usually done on “slow” speed.

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Refinishing Rotors off Vehicle

Use sandpaper or a drill with a sanding pad to give the rotor faces a nondirectional finish.

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Refinishing Rotors off Vehicle

Remeasure the rotor thickness to determine if the rotor is above minimum thickness specifications.

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Inspecting and Replacing Wheel Studs

Inspect the wheel studs and lug nuts for damage. Look for signs of stretched studs, cross-threaded lug nuts, and broken-off studs. Determine if the stud can be removed with the flange on or off the vehicle.

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Inspecting and Replacing Wheel Studs

To perform the drawing-in method, position the flange so the stud has clearance on the back side to be removed.

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Inspecting and Replacing Wheel Studs

Remove any damaged studs with a hammer. Be careful not to damage any of the surfaces on the flange and hub, including the wheel speed sensor and tone ring.

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Inspecting and Replacing Wheel Studs

Insert the stud in the hole in the flange and rotate it so that all of the flutes on the stud line up with the notches in the flange.

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Inspecting and Replacing Wheel Studs

Place enough heavy-duty washers over the stud to prevent the lug nut from bottoming out on the threads.

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Inspecting and Replacing Wheel Studs

Place the lug nut onto the stud, flat side in. Tighten it until the stud bottoms out in the flange. Inspect the threads on the stud and lug nut to make sure they did not get damaged.

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Inspecting and Replacing Wheel Studs

To perform the hydraulic press method, remove the hub and wheel flange from the vehicle following the manufacturer’s procedure.

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Inspecting and Replacing Wheel Studs

Use the press to push out any damaged lug studs.

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Inspecting and Replacing Wheel Studs

Insert the new lug stud into the wheel flange hole. Line up the flutes on the stud with the notches in the flange.

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Inspecting and Replacing Wheel Studs

Support the hub and flange so the press is pushing the stud straight into the flange.

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Inspecting and Replacing Wheel Studs

Push the stud in until it bottoms out in the flange.

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Inspecting and Replacing Wheel Studs

To complete the drawing-in method and the hydraulic press method, verify that each stud is fully seated in the flange.

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Inspecting and Replacing Wheel Studs

Reinstall the hub and flange on the vehicle if it was removed.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Start the lug nuts on the wheel studs, being careful to match up the surfaces.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Carefully run all of the lug nuts down so they are seated in the wheel.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Lower the vehicle so the tires are partially on the ground to keep them from turning while tightening the lug nuts.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Use a torque wrench to tighten each lug nut to the proper torque in the proper sequence.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Once all of the lug nuts have been torqued, go around them again, this time in a circular pattern to ensure that you did not miss any in the previous pattern.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

If the vehicle was equipped with hubcaps and valve stem caps, reinstall them.

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Installing Wheels, Torquing LugNuts, and Making Final Checks

Check the brake fluid level in the master cylinder reservoir. Start the vehicle and check the brake pedal for proper feel and height. Check the parking brake for proper operation. Also inspect the system for any brake fluid leaks and loose or missing fasteners.

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