Brake Caliper - Rear

This procedure covers the removal and replacement of the rear brake caliper on a 2023 Chevrolet Bolt EUV electric vehicle, including brake fluid handling and proper torque specifications.

Warnings

Tools required

Parts

• Rear brake caliper assembly × 1 — Use OEM specification
• Copper crush washers for brake line banjo bolt × 2 — Use OEM specification
• Brake caliper mounting hardware kit (if applicable) × 1 — Use OEM specification

Fluids

• ACDelco DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake (if working on one side at a time, or chock front wheels if working on both rear calipers).
2. Loosen rear wheel lug nuts while vehicle is on the ground, but do not remove.
3. Raise rear of vehicle using floor jack at designated jacking points and support securely on jack stands rated for vehicle weight.
4. Remove rear wheel completely.
5. Locate brake fluid reservoir under hood and check fluid level. Mark current level for reference.
6. Prepare catch pan to collect brake fluid spillage during brake line disconnection.

Procedure

1. 1

   Clean brake caliper and surrounding area
   Use brake cleaner to thoroughly clean the rear brake caliper, mounting bracket, and brake line connection area. Remove dirt, road salt, and debris to prevent contamination of the brake system during disassembly. Allow to dry completely.
2. 2

   Disconnect brake line from caliper
   Position catch pan under brake line connection. Using a line wrench to prevent rounding, carefully loosen and remove the brake line banjo bolt from the rear caliper. Allow brake fluid to drain into catch pan. Remove and discard the two copper crush washers (one on each side of the banjo fitting). Immediately plug or cap the brake line and caliper port to prevent fluid loss and contamination.
   ⚠Use a line wrench (flare nut wrench) to avoid rounding the banjo bolt. Standard open-end wrenches may slip and damage the fitting.
   Torque spec

   Brake Line Banjo Bolt25 Nm (18 lb-ft)
3. 3

   Remove caliper mounting bolts
   Locate the two caliper mounting bolts that secure the caliper to the mounting bracket. These are typically located on the inboard side of the caliper. Using the appropriate socket, remove both caliper mounting bolts completely. Note the condition of bolt threads and replace if damaged.
4. 4

   Remove caliper from mounting bracket
   Carefully lift the caliper assembly off the mounting bracket and away from the brake rotor. Support the caliper weight and ensure brake pads remain in position or remove them for inspection. Do not allow the caliper to hang by the brake line (already disconnected in this procedure).
5. 5

   Inspect mounting bracket and hardware
   Examine the caliper mounting bracket for wear, cracks, or damage. Inspect the brake rotor surface for scoring or excessive wear. Check brake pad thickness and condition. Clean the mounting bracket slide surfaces with a wire brush and brake cleaner. If bracket removal is necessary for replacement or service, remove the bracket bolts.
   ℹ️Minimum brake pad thickness is typically 2mm. Replace pads if at or below minimum specification.
   Torque spec

   Caliper Bracket Bolts100 Nm (74 lb-ft)
6. 6

   Prepare new caliper for installation
   Remove the new caliper from packaging and verify it matches the old unit. Remove any protective caps or plugs from brake line port. If caliper pistons are not fully retracted, carefully compress them using a C-clamp or caliper compression tool. Ensure caliper bleeder screw moves freely (do not force).
7. 7

   Install new caliper onto mounting bracket
   Position the new caliper over the brake rotor and onto the mounting bracket. Ensure brake pads are properly seated in bracket and that caliper slides smoothly into position. Verify correct orientation (bleeder screw should be at top position).
   ⚠Ensure brake pads are properly positioned and seated before securing caliper. Improper pad installation can cause brake noise or failure.
8. 8

   Install and torque caliper mounting bolts
   Apply medium-strength thread locker to the threads of both caliper mounting bolts. Insert bolts and hand-tighten. Using a torque wrench, tighten caliper mounting bolts to specification in a cross pattern (alternating between bolts). Verify caliper is secure and properly seated.
   ⚠️Caliper mounting bolts MUST be torqued to exact specification. Under-torquing can allow caliper to detach during braking; over-torquing can strip threads or break bolts.
9. 9

   Reconnect brake line to caliper
   Install NEW copper crush washers on both sides of the brake line banjo fitting (one washer between banjo bolt head and fitting, one between fitting and caliper body). Position brake line banjo fitting into caliper port, ensuring proper alignment. Insert banjo bolt and hand-tighten. Using a line wrench and torque wrench, tighten brake line banjo bolt to specification. Do not over-torque.
   ⚠️Always use NEW copper crush washers. Reused washers will not seal properly and will cause brake fluid leaks and potential brake failure.
   Torque spec

   Brake Line Banjo Bolt25 Nm (18 lb-ft)
10. 10

    Bleed rear brake caliper
    Attach bleeder hose to caliper bleeder screw and route into catch container. Have assistant pump brake pedal 3-4 times and hold pressure, or use vacuum bleeder. Open bleeder screw slightly (1/4 to 1/2 turn) and allow fluid and air to escape. Close bleeder screw before releasing pedal pressure. Repeat until fluid flows clear without air bubbles. Check brake fluid reservoir frequently and maintain proper level during bleeding. Tighten bleeder screw to specification when complete.
    ⚠️Air in brake lines will cause spongy pedal feel and reduced braking performance. Bleed thoroughly until all air is removed and pedal feels firm.
    ⚠Bleeder screw is brass and easily damaged. Do not exceed specified torque or apply excessive force.
    Torque spec

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

    Reinstall wheel and lower vehicle
    Clean wheel mounting surface on hub with wire brush. Position wheel onto hub and hand-thread all lug nuts. Tighten lug nuts in star pattern using torque wrench to proper specification. Lower vehicle from jack stands and remove stands. With vehicle weight on ground, perform final torque check of lug nuts in star pattern.
    ⚠️Improperly torqued lug nuts can cause wheel detachment. Always torque in star pattern and verify final torque with vehicle on ground.

Reassembly

1. Refill brake fluid reservoir to MAX line with fresh ACDelco DOT 4 brake fluid.
2. If both rear calipers were replaced, bleed the brake system starting from the wheel furthest from the master cylinder (typically right rear, then left rear, then right front, then left front).
3. Check all brake line connections for leaks while assistant applies firm pedal pressure.
4. Clean any brake fluid residue from caliper, rotor, and surrounding components using brake cleaner and clean rags.

Verification

• Pump brake pedal several times. Pedal should feel firm and consistent with normal travel. If pedal feels spongy or goes to floor, system contains air and requires additional bleeding.
• With engine running (or vehicle in READY mode for EV), apply firm brake pressure and hold for 30 seconds. Pedal should not sink or feel soft. Check all connections for fluid leaks.
• Perform low-speed test drive in safe area (parking lot). Test brakes at 5-10 mph to verify proper operation. Braking should be smooth without pulling to one side.
• After test drive, re-check brake fluid level and inspect caliper/brake line connections for any signs of leakage.
• Verify no warning lights are illuminated on instrument cluster. If brake warning light remains on, diagnose issue before returning vehicle to service.
• Bed in new caliper/pads according to manufacturer recommendations (typically 20-30 moderate stops from 30 mph with cool-down period between sets).

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