Disc Brake System: Diagnosis Chevrolet Silverado Classic 1500

Diagnostic Starting Point - Disc Brakes

Begin the disc brake system diagnosis with Diagnostic Starting Point - Hydraulic Brakes . The use of the Diagnostic Starting Point will lead to the identification of the correct procedure for diagnosing the system and where the procedure is located.

Brake Rotor Surface and Wear Inspection

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads. Refer to «Front Disc Brake Pads Replacement (1500 Series)»(ref-277897-S42462250402008012100000) or «Front Disc Brake Pads Replacement (25/3500 Series)»(ref-277897-S19510257572008012100000) and/or «Rear Disc Brake Pads Replacement (1500 Series)»(ref-277897-S40260797072008012100000) or «Rear Disc Brake Pads Replacement (25/3500 Series)»(ref-277897-S24596849302008012100000) .
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Inspect the friction surfaces of the brake rotor for the following Braking Surface Conditions: Heavy rust and/or pitting Light surface rust can be removed with an abrasive disc. Heavy surface rust and/or pitting must be removed by refinishing the rotor. Cracks and/or heat spots Excessive blueing discoloration
4. If the friction surfaces of the brake rotor exhibit one or more of the Braking Surface Conditions, the rotor requires refinishing or replacement.
5. Using a micrometer calibrated in thousanths-of-a-millimeter, or ten-thousanths-of-an-inch, measure and record the scoring depth of any grooves present on the rotor friction surfaces.
6. Compare the groove scoring depth recorded to the following specification: Specification: Brake rotor maximum allowable scoring: 1. 50 mm (0. 059 in)
7. If the brake rotor scoring depth exceeds the specification, or if an excessive amount of scoring is present, the rotor requires refinishing or replacement.

Brake Pad Inspection

1. Inspect the disc brake pads at regular intervals, or whenever the tire and wheel assemblies are removed from the vehicle.
2. If replacement is necessary, always replace disc brake pads in axle sets.
3. Inspect both edges of the disc brake pad friction surfaces (3). The highest rate of wear normally occurs at the trailing edge of the disc brake pads.
4. Inspect the thickness of the disc brake pads (3) in order to ensure that they have not worn prematurely. The disc brake pad wear should be approximately even per axle set.
5. Both front and rear disc brake pads have integral, audible wear sensors (1). When the disc brake pad wear reaches the minimum allowable thickness, the wear sensor contacts the disc brake rotor (2). The wear indicator will then produce an audible, high-pitched warning noise during wheel rotation.
6. Replace the disc brake pads when the friction surface (3) is worn to within 0. 76 mm (0. 030 in) of the audible wear sensors.
7. Remove the brake calipers and inspect the friction surfaces of the inner and outer disc brake pads to ensure that they are level. Place the disc brake pad friction surfaces together and measure the gap between the surfaces. If more than 0. 13 mm (0. 005 in) gap exists midway between the length of the disc brake pads, replace the disc brake pads.
8. Verify that any disc brake pad shims that may be required are in place and not damaged or excessively corroded. Replace any missing or damaged shims in order to preserve proper disc brake performance.
9. Replace the disc brake pads if any have separated from the mounting plates.
10. Inspect the disc brake pads friction surfaces for cracks, fractures, or damage which may cause noise or otherwise impair disc brake performance.

Brake Caliper Inspection

Off Vehicle Inspection

1. Inspect the brake caliper housing (1) for cracks, excess wear, and/or damage. If any of these conditions are present, the brake caliper requires replacement.
2. Inspect the caliper piston dust boot seal (2) for cracks, tears, cuts, deterioration and/or improper seating in the caliper body. If any of these conditions are present, the brake caliper requires overhaul or replacement.
3. Inspect for brake fluid leakage around the caliper piston dust boot seal (2) and on the disc brake pads. If there is any evidence of brake fluid leakage, the brake caliper requires overhaul or replacement.
4. Inspect for smooth and complete travel of the caliper pistons into the caliper bores: The movement of the caliper pistons into the caliper bores should be smooth and even. If the caliper piston is frozen or difficult to bottom, the caliper requires overhaul or replacement. For single piston caliper applications, insert a discarded inner brake pad (2) or block of wood in front of the piston. Using a large C-clamp (1) installed over the body of the caliper (3) and against the brake pad or block of wood, slowly bottom the piston in the bore. For dual piston caliper applications, insert a discarded inner brake pad (2) or block of wood in front of the pistons. Using 2 large C-clamps (1) installed over the body of the caliper (3) and against the brake pad or block of wood, slowly bottom the pistons evenly into the bores.

Front Disc Brake Mounting and Hardware Inspection

1. Inspect the fluid level in the brake master cylinder reservoir.
2. If the brake fluid level is midway between the maximum-full point and the minimum allowable level then no brake fluid needs to be removed from the reservoir before proceeding.
3. If the brake fluid level is higher than midway between the maximum-full point and the minimum allowable level then remove brake fluid to the midway point before proceeding.
4. Raise and support the vehicle. Refer «Lifting and Jacking the Vehicle»(ref-277851-S21776392712008012100000) .
5. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(ref-277896-S27966091872008012100000) .
6. Grasp the brake caliper housing and try to move the brake caliper housing up/down and forward/reverse in relation to the brake caliper mounting bracket. If excessive looseness is observed the brake caliper bracket bushings and/or the brake caliper mounting bolts may need to be replaced.
7. Compress the front caliper pistons. Install a large C-clamp over the top of the caliper housing and against the back of the outboard pad. Slowly tighten the C-clamp until the pistons are pushed completely into the caliper bores. Remove the C-clamp from the caliper.
8. With the pistons compressed into the caliper bores, grasp the brake caliper housing and slide it back and forth on the brake caliper mounting bolts. Check for smooth operation. If the brake caliper housing slide force is high or the brake caliper housing does not slide smoothly, inspect the brake caliper mounting bolts and/or the brake caliper mounting bracket bushings for wear or damage. If wear or damage conditions are found, replacement of the brake caliper mounting bolts and/or the brake caliper mounting bracket bushings is necessary.
9. Remove the brake caliper mounting bolts from the brake caliper mounting bracket and support the brake caliper using heavy mechanics wire. Do Not remove the hydraulic brake hose from the caliper. Refer to «Front Brake Caliper Replacement (1500 Series)»(ref-277897-S37008799642008012100000) or «Front Brake Caliper Replacement (2500 Series)»(ref-277897-S25883659612008012100000) .
10. Remove the disc brake pads from the brake caliper mounting bracket.
11. Inspect the disc brake pad mounting hardware for the following: Missing mounting hardware Excessive corrosion Bent mounting tabs Looseness at the brake caliper mounting bracket Looseness at the disc brake pads Excessive contaminants in the brake caliper mounting bracket surface and threads.
12. If any of the conditions listed are found, the disc brake pad mounting hardware requires replacement.
13. Ensure the disc brake pads are held firmly in place on the brake caliper mounting bracket, yet slide easily on the mounting hardware without binding.
14. Inspect the caliper bolts (1) for the following: Binding Seizing Looseness in the brake caliper mounting bracket (3) Bent or damaged brake caliper mounting bolts Cracked or torn boots (4) Missing boots Bent or damaged brake caliper mounting bracket (3)
15. If any of the conditions listed are found then the brake caliper mounting hardware requires replacement.
16. Install the disc brake pads to the brake caliper mounting bracket.
17. Install the disc brake caliper to the brake caliper mounting bracket. Refer to «Front Brake Caliper Replacement (1500 Series)»(ref-277897-S37008799642008012100000) or «Front Brake Caliper Replacement (2500 Series)»(ref-277897-S25883659612008012100000) .

Rear Disc Brake Mounting and Hardware Inspection (1500 Series)

1. Inspect the fluid level in the brake master cylinder reservoir.
2. If the brake fluid level is midway between the maximum-full point and the minimum allowable level, no brake fluid needs to be removed from the reservoir before proceeding.
3. If the brake fluid level is higher than midway between the maximum-full point and the minimum allowable level, remove brake fluid to the midway point before proceeding.
4. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-277851-S21776392712008012100000) .
5. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(ref-277896-S27966091872008012100000) .
6. Grasp the brake caliper housing and try to move the brake caliper housing up/down and forward/reverse in relation to the brake caliper mounting bracket. If excessive looseness is observed the brake caliper bracket bushings and/or the brake caliper mounting bracket slide pins may need to be replaced.
7. Compress the rear caliper piston. Install a large C-clamp over the top of the caliper housing and against the back of the outboard pad. Slowly tighten the C-clamp until the piston is pushed completely into the caliper bore. Remove the C-clamp from the caliper.
8. With the piston compressed into the caliper bore, grasp the caliper housing and slide it back and forth along the brake caliper mounting bracket slide pins. Check for smooth operation. If the brake caliper slide force is high or the brake caliper housing does not slide smoothly, inspect the brake caliper mounting bracket slide pins and/or the brake caliper mounting bracket bushings for wear or damage. If wear or damage conditions are found, replacement of the brake caliper mounting bracket slide pins and/or the brake caliper mounting bracket bushings is necessary.
9. Remove the brake caliper mounting bolts and support the brake caliper using heavy mechanics wire. Do Not remove the hydraulic brake hose from the caliper. Refer to «Rear Brake Caliper Replacement»(ref-277897-S27043286132008012100000) .
10. Remove the disc brake pads from the brake caliper mounting bracket.
11. Inspect the disc brake pad mounting hardware for the following: Missing mounting hardware Excessive corrosion Bent mounting tabs Looseness at the brake caliper mounting bracket Looseness at the disc brake pads Excessive contaminants in the brake caliper mounting bracket surface and threads.
12. If any of the conditions listed are found, the disc brake pad mounting hardware requires replacement.
13. Ensure the disc brake pads are held firmly in place on the brake caliper mounting bracket, yet slide easily on the mounting hardware without binding.
14. Inspect the brake caliper mounting bracket slide pins (5) for the following: Binding Seizing Looseness in the caliper mounting bracket (3) Bent or damaged brake caliper mounting bolts (1). Cracked or torn boots (4) Missing boots Bent or damaged brake caliper mounting bracket (3)
15. Replace any parts found to have the one of the above conditions.
16. Install the disc brake pads to the brake caliper mounting bracket.
17. Install the disc brake caliper to the brake caliper mounting bracket. Refer to «Rear Brake Caliper Replacement»(ref-277897-S27043286132008012100000) .

Rear Disc Brake Mounting and Hardware Inspection (25/3500 Series)

1. Inspect the fluid level in the brake master cylinder reservoir.
2. If the brake fluid level is midway between the maximum-full point and the minimum allowable level then no brake fluid needs to be removed from the reservoir before proceeding.
3. If the brake fluid level is higher than midway between the maximum-full point and the minimum allowable level then remove brake fluid to the midway point before proceeding.
4. Raise and support the vehicle. Refer «Lifting and Jacking the Vehicle»(ref-277851-S21776392712008012100000) .
5. Remove the tire and wheel assembly. Refer to «Tire and Wheel Removal and Installation»(ref-277896-S27966091872008012100000) .
6. Grasp the brake caliper housing and try to move the brake caliper housing up/down and forward/reverse in relation to the brake caliper mounting bracket. If excessive looseness is observed the brake caliper bracket bushings and/or the brake caliper mounting bolts may need to be replaced.
7. Compress the rear brake caliper pistons. Install a large C-clamp over the top of the caliper housing and against the back of the outboard pad. Slowly tighten the C-clamp until the pistons are pushed completely into the caliper bores. Remove the C-clamp from the caliper.
8. With the pistons compressed into the caliper bores, grasp the brake caliper housing and slide it back and forth on the brake caliper mounting bolts. Check for smooth operation. If the brake caliper housing slide force is high or the brake caliper housing does not slide smoothly, inspect the brake caliper mounting bolts and/or the brake caliper mounting bracket bushings for wear or damage. If wear or damage conditions are found, replacement of the brake caliper mounting bolts and/or the brake caliper mounting bracket bushings is necessary.
9. Remove the brake caliper mounting bolts from the brake caliper mounting bracket and support the brake caliper using heavy mechanics wire. Do Not remove the hydraulic brake hose from the caliper. Refer to «Rear Brake Caliper Replacement»(ref-277897-S27043286132008012100000) .
10. Remove the disc brake pads from the brake caliper mounting bracket.
11. Inspect the disc brake pad mounting hardware for the following: Missing mounting hardware Excessive corrosion Bent mounting tabs Looseness at the brake caliper mounting bracket Looseness at the disc brake pads Excessive contaminants in the brake caliper mounting bracket surface and threads.
12. If any of the conditions listed are found, the disc brake pad mounting hardware requires replacement.
13. Ensure the disc brake pads are held firmly in place on the brake caliper mounting bracket, yet slide easily on the mounting hardware without binding.
14. Inspect the caliper bolts (1) for the following: Binding Seizing Looseness in the brake caliper mounting bracket (3) Bent or damaged brake caliper mounting bolts Cracked or torn boots (4) Missing boots Bent or damaged brake caliper mounting bracket (3)
15. If any of the conditions listed are found then the brake caliper mounting hardware requires replacement.
16. Install the disc brake pads to the brake caliper mounting bracket.
17. Install the disc brake caliper to the brake caliper mounting bracket. Refer to «Rear Brake Caliper Replacement»(ref-277897-S27043286132008012100000) .