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Question

Difficulty: MediumBraking Systems

When replacing worn front disc brake pads on a passenger vehicle, what is the correct chronological sequence of steps a technician must perform?

  1. 1Safely raise the vehicle on jack stands and remove the front wheel assembly.
  2. 2Unbolt the caliper mounting fasteners and suspend the caliper body with a wire hanger.
  3. 3Retract the caliper piston back into its bore using a piston compression tool.
  4. 4Install the new brake pads and abutment hardware into the caliper mounting bracket.
  5. 5Reinstall the caliper assembly and depress the brake pedal repeatedly until firm.

Answer

The correct service sequence begins with safely raising the vehicle and removing the wheel, unbolting and suspending the caliper, compressing the caliper piston into the bore, installing the new pads and hardware, and finally reinstalling the caliper and pumping the brake pedal to establish contact with the rotor.
The service procedure follows a strict mechanical logic: initial vehicle lifting and wheel removal provide component access; unbolting and hanging the caliper prevents hydraulic hose strain; retracting the piston creates clearance for the thicker new pads; positioning the new pads and hardware prepares the friction assembly; and finally, reinstalling the caliper followed by pumping the brake pedal seats the piston against the pads to ensure immediate brake responsiveness.

Step-by-Step Solution

1
Elevate and secure the vehicle on jack stands, then remove the lug nuts and wheel assembly.
Provides clear access to the disc brake caliper and rotor assembly.
Physical access to the braking hardware requires wheel removal while maintaining shop safety protocols.
2
Remove the caliper guide pins or bolts and support the caliper body with a wire hook.
Frees the caliper without placing tensile load on the flexible hydraulic hose.
Allowing the heavy steel caliper to hang by its flexible rubber brake hose can cause internal ruptures or leaks.
3
Push the caliper piston completely back into the cylinder bore with a C-clamp or pad spreader.
Increases the gap between the piston face and caliper housing.
As brake pads wear down, the piston extends outward; new, full-thickness pads will not fit over the rotor without resetting piston travel.
4
Fit new abutment clips and slide the replacement brake pads into the caliper bracket.
Aligns the new friction material parallel to the brake rotor braking surface.
The brake pads must be securely mounted in their guide clips before the caliper housing is lowered back over them.
5
Torque the caliper bolts to specification and pump the brake pedal several times before driving.
Displaces hydraulic fluid to advance the piston firmly against the backing plate.
Because the piston was fully retracted, failing to pump the pedal causes excessive pedal travel and complete initial braking loss.

Key Concept

Disc brake pad replacement and caliper servicing procedure
Estimated Time:1m 0s
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Topics

Braking Systems

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