Brake Caliper Rebuild - Front

Complete disassembly, cleaning, inspection, and rebuild of front brake calipers including replacement of seals, boots, and pistons as needed.

Warnings

Tools required

Parts

• Front brake caliper rebuild kit (seals, boots, pistons) × 2 — Use OEM specification for 2023 Bolt EUV
• Brake fluid × 1 — ACDelco DOT 4
• Brake hardware kit (if slides worn) × 1 — Optional - inspect condition

Fluids

• ACDelco DOT 4 Brake Fluid — 1 qt

Preparation

1. Ensure vehicle is parked on level ground and ignition is OFF with key removed
2. Disable electronic parking brake: Press brake pedal, press and hold parking brake switch for 3 seconds until service mode activates
3. Chock rear wheels securely
4. Remove reservoir cap from brake master cylinder and place clean cloth over opening to prevent contamination
5. Lift front of vehicle and support on jack stands at manufacturer's designated lift points
6. Remove front wheels
7. Inspect brake system for damage, excessive wear, or contamination that would require additional parts
8. Have new brake fluid, rebuild kits, and all tools ready before opening brake system
9. Clean exterior of caliper thoroughly with brake cleaner to prevent contamination during rebuild

Procedure

1. 1

   Remove caliper from vehicle
   Place drain pan under caliper. Using a brake line wrench, loosen the brake line fitting at the caliper. Remove the caliper slide pin bolts and lift caliper off bracket. Finish removing brake line fitting. Cap or plug the brake line immediately to prevent fluid loss and contamination. Support caliper on clean work surface.
   ⚠Use only a line wrench on brake line fittings to prevent rounding. Do not use open-end wrenches.
   ⚠Brake fluid will drain from line. Have catch pan positioned and plug line immediately.
   Torque spec

   Caliper Slide Pin Bolts35 Nm (26 lb-ft)

   Line Fittings20 Nm (15 lb-ft)
2. 2

   Disassemble caliper housing
   Remove the slide pins from caliper bracket if servicing. On the caliper body, carefully remove dust boots from piston(s). Use compressed air through the brake fluid inlet port to push piston(s) out of bore. Apply air gradually and control piston ejection with a rag - do not allow piston to shoot out forcefully. Remove pistons completely from caliper bore.
   ⚠️Compressed air can cause piston to eject violently causing injury. Use low pressure and keep hands clear of piston path. Place rag over piston to control ejection.
   ⚠If multiple pistons, remove all simultaneously to prevent binding. Apply air gradually.
3. 3

   Remove internal seals
   Using a plastic or wooden pick (never metal tools in bore), carefully pry out the internal piston seals from their grooves in the caliper bore. Inspect seal grooves for scoring, corrosion, or damage. If bore shows deep scoring or corrosion that cannot be cleaned, caliper must be replaced - do not attempt rebuild.
   ⚠Do not use metal tools inside caliper bore. Metal picks will scratch bore surface causing seal leaks and caliper failure.
4. 4

   Clean all components
   Thoroughly clean caliper bores, piston surfaces, and all internal passages with brake parts cleaner. Use wire brush on external surfaces only. Dry with compressed air if available. Inspect caliper bores for pitting, scoring, or corrosion. Inspect pistons for chrome plating damage, pitting, or scoring. Replace any damaged components. Clean slide pins and pin bores in bracket thoroughly.
5. 5

   Inspect and prepare new parts
   Verify rebuild kit contents match caliper requirements. Check that new pistons (if included) are correct size and type. Ensure all seals and boots are undamaged. Lubricate new piston seals lightly with clean brake fluid from sealed container. Lubricate piston bore with clean brake fluid. Do not use any petroleum-based lubricants on brake system components.
   ⚠️Never use petroleum-based lubricants (grease, oil) on brake system rubber components. This will cause seal failure and brake system malfunction. Use only clean brake fluid or silicone brake grease where specified.
6. 6

   Install new seals
   Install new piston seals into caliper bore grooves by hand. Ensure seals are properly seated in their grooves with no twists or folds. Work seal into groove carefully around entire circumference. Verify seal sits evenly in groove before proceeding.
7. 7

   Install pistons and boots
   Coat new or cleaned piston with clean brake fluid. Carefully insert piston into caliper bore by hand, applying even pressure. Push piston squarely into bore to avoid cocking or seal damage. Push piston until it bottoms in bore. Install new dust boot onto piston and seat boot lip into caliper housing groove. Ensure boot is fully seated around entire circumference.
   ⚠Piston must enter bore squarely. Cocked piston will damage new seal causing leaks. Apply even pressure and verify seal does not pop out during installation.
8. 8

   Service caliper bracket and slides
   Clean slide pin bores in bracket thoroughly with wire brush and brake cleaner. Inspect slide pins for corrosion, wear, or damaged boots. If worn, replace with new hardware kit. Apply thin coat of silicone brake grease to slide pins (not petroleum grease). Install slide pins into bracket with new boots if needed. Verify pins slide freely in bores.
   Torque spec

   Caliper Slide Pin Bolts35 Nm (26 lb-ft)
9. 9

   Install caliper to vehicle
   Remove plug from brake line. Position caliper over brake pads and bracket. Install caliper slide pin bolts with silicone brake grease on threads and torque to specification. Thread brake line fitting into caliper by hand first to prevent cross-threading. Using line wrench, torque brake line fitting to specification. Do not overtighten.
   ⚠Start brake line fitting by hand. If resistance is felt, do not force - remove and inspect threads for damage or cross-threading.
   Torque spec

   Caliper Slide Pin Bolts35 Nm (26 lb-ft)

   Line Fittings20 Nm (15 lb-ft)
10. 10

    Bleed brake system
    Fill brake fluid reservoir to MAX line with fresh DOT 4 brake fluid. Attach clear bleeder tube to caliper bleeder screw with other end submerged in clean brake fluid in catch bottle. Have assistant pump brake pedal 3-4 times and hold pressure. Open bleeder screw 1/2 turn while pedal is held. Close bleeder screw before pedal reaches floor. Repeat until fluid runs clear with no air bubbles. Torque bleeder screw to specification. Check reservoir level frequently and refill to prevent running dry.
    ⚠️Never allow brake fluid reservoir to run empty during bleeding. Air entering ABS system requires professional scan tool to bleed properly.
    ⚠Bleeder screw is brass and easily damaged. Torque carefully to specification - overtightening will strip threads.
    Torque spec

    Bleeder Screw10 Nm (7 lb-ft)
11. 11

    Repeat for opposite side
    Repeat entire rebuild procedure (steps 1-10) for the opposite front caliper. Bleed opposite caliper using same procedure. After both calipers are rebuilt and bled, verify brake fluid reservoir is at MAX level. Firmly pump brake pedal until pedal feels firm and consistent.
12. 12

    Final inspection and reinstall wheels
    Inspect all brake line connections for leaks. Verify caliper slide pin bolts are properly torqued. Check that dust boots are properly seated. Reinstall front wheels and torque lug nuts in star pattern to specification. Lower vehicle from jack stands.
    ⚠Lug nuts must be torqued in proper star pattern to prevent rotor warping. Use calibrated torque wrench.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Verify brake fluid reservoir is at MAX level with fresh DOT 4 fluid
2. Release electronic parking brake from service mode if applicable
3. Dispose of old brake fluid according to local environmental regulations - never pour down drain
4. Clean any brake fluid spills from vehicle immediately to prevent paint damage
5. All fasteners with [CRITICAL] designation must be torqued precisely to specification

Verification

• Start vehicle and pump brake pedal firmly 10-15 times. Pedal should become firm and hold steady pressure. If pedal is soft or sinks, system requires additional bleeding
• With vehicle running, press brake pedal firmly and hold for 30 seconds. Pedal should not sink - if it does, there is a leak or air in system
• Check all brake line fittings and caliper bleeder screws for leaks with pedal pressure applied
• Test drive in safe area at low speed (under 15 mph). Verify brakes apply smoothly without pulling to one side
• After test drive, recheck all fastener torques and inspect for any fluid leaks
• Perform several moderate brake applications from 30-40 mph in safe area to verify proper function and seating of components
• Check brake fluid level after test drive and top off if needed
• Monitor brake performance for first 100 miles and recheck fluid level and fastener torques after 50 miles of driving

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