how to change brake pads 1990 chevrolet corvette?

There are instructions for both rear and front brake pads:----

Brake Pads

REMOVAL & INSTALLATION

CAUTION

Older brake pads or shoes may contain asbestos, which has been determined to be cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

Front

See Figures 1, 2, 3, 4, 5, 6 and 7

1. Disconnect the negative battery cable and use a clean turkey baster, or equivalent siphon to remove ² / ₃ of the brake fluid from the master cylinder reservoir. Install the reservoir cap.
2. Raise and safely support the vehicle.
3. Mark the relationship between the wheel to the axle flange.
4. Remove the tire and wheel assembly. Install 2 lug nuts to hold the brake rotor in place.
5. Use a large C-clamp or pair of pliers to compress the caliper piston into its bore. Make sure one end of the C-clamp rests on the inlet fitting bolt head at the other rests against the outboard shoe, then tighten the C-clamp to push the piston into the bore. There are also special tools available to compress the caliper piston.

Fig. Fig. 1: Use a large C-clamp to compress the caliper piston into its bore

6. For 1984-87 vehicles, perform the following:
   1. Hold the guide pin bolt in place with a wrench, then loosen the top caliper self-locking bolt.
   2. Remove the bolt, then rotate the caliper housing down for access to the brake pads.
   3. Discard the self-locking bolt and replace with a new one during installation.

   
   

Fig. Fig. 2: While holding the guide pin bolt stationary with a wrench, loosen the top caliper self-locking bolt

Fig. Fig. 3: Remove the bolt, then rotate the caliper down to access the brake pads

7. For 1988-96 vehicles, perform the following:
   1. Remove the circlip and retainer pin.
   2. Remove the caliper housing from the rotor and caliper mounting bracket.
   3. Suspend the caliper housing from the upper control arm using a piece of wire, such as a clothes hanger.

   
   
8. Remove the outboard and inboard brake pads. Clean all dirt and residue from the pad abutments on the mounting bracket and from the inside of the housing outer legs.

Fig. Fig. 4: Remove the outboard brake pad (1) and shim (2) ...

Fig. Fig. 5: ... then remove the inboard brake pad from the caliper

Fig. Fig. 6: Exploded view of the inboard and outboard brake pads-1996 vehicle shown

9. Check to make sure the guide pins move freely in the bracket. Replace the guide pins or boots if they are corroded or damaged.

Fig. Fig. 7: Another way to push the piston in the caliper bore is to use this type of caliper piston compressor tool

To install:

10. For 1984-87 vehicles, install new inboard and outlet pads on the mounting bracket. The pad with the insulator is installed outboard and the pad with the wear sensor is installed inboard. The wear sensor must be in the trailing position with forward wheel rotation. If not, use the other inboard pad in the replacement set.
11. For 1988-96 vehicles, install the brake pads, pressing them firmly in place until they are flush and fully seated in the caliper housing and pistons. The outboard brake pad with the insulator is installed in the caliper housing, and the inboard brake pad with the wear sensor is pressed into the caliper piston.
12. For 1984-87 vehicles, perform the following:
    1. Rotate the caliper back into its original position. Check the shoe springs; if they protrude through the inspection hole, rotate the caliper back down and readjust.
    2. Install a new self-locking bolt and tighten to 22-25 ft. lbs. (30-34 Nm).

    
    
13. For 1988-96 vehicles, perform the following:
    1. Position the housing over the rotor and into the caliper mounting bracket. Make sure the guiding surfaces on the brake pads are seated correctly in the mounting bracket.
    2. Install a new retaining pin and circlip. Press the housing down into the mounting bracket to compress the bias springs. Slide the retainer pin into position and install the circlip.

    
    
14. Remove the lug nuts from the rotor, then install the wheel and tire assembly and hand-tighten the lug nuts.
15. Carefully lower the vehicle, then tighten the lug nuts to 100 ft. lbs. (136 Nm).
16. Remove the reservoir cap and fill the master cylinder reservoir with the proper type and amount of fluid.
17. Depress the brake pedal firmly about 3 times to proper seat the pads. Check the fluid level and add if necessary.

Rear

See Figures 8, 9, 10 and 11

1. Disconnect the negative battery cable and remove ² / ₃ of the brake fluid from the master cylinder reservoirs.
2. Raise and support the vehicle safely.
3. Mark the relationship between the wheel to the axle flange.
4. Remove the tire and wheel assembly. Install 2 lug nuts to hold the brake rotor in place.
5. Use a C-clamp to depress the caliper pistons into the caliper bores to provide clearance between the pads and the rotor. Make sure 1 end of the clamp rests on the inlet fitting bolt while the other end rests on the outboard pad.
6. Remove the caliper upper guide pin bolt and discard, then rotate the caliper on the lower guide pin to access the pad linings. Be careful not to strain the cable conduit or the hoses.

Fig. Fig. 8: Remove the bolt, then rotate the caliper down for access to the pads

Fig. Fig. 9: Allow the caliper to rotate down in order to replace the brake pads-1996 vehicle shown

7. Remove the inboard and outboard pads from the caliper.

Fig. Fig. 10: Remove the inboard (1) and outboard (2) pads from the caliper

Fig. Fig. 11: The inboard rear brake pad usually has a wear sensor to let you know your brakes are getting low

To install:

8. Install the outboard pad with the insulator to the caliper housing and the inboard pad with the wear sensor nearest the caliper pistons. The wear sensor must be in the trailing position during forward wheel rotation. Press the pads firmly until they are they are fully seated.
9. Rotate the caliper housing into position, then install a new upper guide pin bolt and tighten 26 ft. lbs. (35 Nm).
10. Remove the wheel nuts securing the rotor to the hub and install the tire and wheel assembly.
11. Lower the vehicle and fill the master cylinder to the proper level with clean brake fluid.
12. Connect the negative battery cable, start the engine and pump the brake pedal slowly and firmly 3 times to seat the shoe and lining assemblies.

INSPECTION

You should check the brake pads every 6,000 miles (9,600km), and any time the wheels are removed. Inspect both ends of the outer brake pad by looking in at each end of the caliper. These are the points at which the highest rate of wear normally occurs. Also, check the thickness on the inner brake pad to make sure it is not wearing prematurely. Some inboard pads have a thermal layer against the steel backing surface which is integrally molded with the pad. Do not confuse this extra layer with uneven inboard/outboard brake pad wear.

Look down through inspection hole in the top of the caliper to view the inner brake pad. Replace the pads whenever the thickness of any pad is worn within 0.030 in. (0.76mm) of the steel backing surface. For riveted brake pads, they must be replaced if the pad is worn to 0.030 (0.76mm) of any rivet head. The disc brake pads MUST be replaced in axle sets, for example, if you replace the drivers side front brake pads, you must also replace the passengers side front brake pads. This will prevent uneven wear and other brake system problems.

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Brake Caliper

REMOVAL & INSTALLATION

CAUTION

Older brake pads or shoes may contain asbestos, which has been determined to be cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

Front

See Figures 1, 2, 3, 4, 5, 6, 7 and 8

1. Disconnect the negative battery cable and use a clean turkey baster, or equivalent siphon to remove ² / ₃ of the brake fluid from the master cylinder reservoir.
2. Raise and support the vehicle safely.
3. Mark the relationship between the wheel and axle flange, then remove the tire and wheel assembly.
4. Install 2 lug nuts to hold the brake rotor in place.
5. Use a large C-clamp or pair of pliers to depress the caliper pistons into the caliper bores in order to provide clearance between the pads and the rotor.
6. If the caliper is being completely removed from the vehicle for replacement or overhaul, disconnect the brake line fitting at the caliper by removing the bolt, 2 gaskets and then the brake hose inlet fitting. Plug all openings to prevent fluid contamination or loss.

Fig. Fig. 1: If you are replacing or overhauling the caliper, remove the fluid inlet fitting and line from the caliper

Do not allow the fluid to come into contact with the front transverse spring as damage to the spring may occur.

7. For 1984-87 vehicles, there are two methods you can use to remove the caliper, depending upon whether you want to remove the caliper housing and mounting bracket separately, or as an assembly. Read both options, and pick the one thats suitable for you:
   1. Method 1: Hold the guide pin bolt in place with a wrench, then loosen the top caliper self-locking bolt. Do the same with the bottom guide pin bolt and self-locking bolt, then remove the caliper housing, or if the brake line is still attached, support the caliper from the control arm with a suitable hook or length of mechanic's wire. If necessary, unfasten the bracket mounting bolts and washers, then remove the bracket from the rotor.

   
   

Fig. Fig. 2: Exploded view of the caliper mounting bracket-1987 vehicle shown

2. Method 2: Unfasten the 2 bracket mounting bolts and washers, then remove the bracket and caliper housing as a single assembly.
3. Discard the bracket mounting bolts, then clean the old bolt adhesive from the mounting bracket threads.

Fig. Fig. 3: If the caliper is being completely removed, you must disconnect the brake line (1) and remove the bracket mounting bolts (2)

Fig. Fig. 4: Then, you can remove the entire caliper and brake assembly from the vehicle

8. For 1988-96 vehicles, perform the following:
   1. Remove the circlip and the retainer pin, then the caliper housing from the rotor and the caliper mounting bracket. Remove the caliper from the vehicle or if the brake line is still attached, support the caliper from the control arm with a suitable hook or length of mechanic's wire.

   
   

Fig. Fig. 5: Use a pair of needle-nose pliers to remove the circlip ...

Fig. Fig. 6: ... then remove the retainer pin

Fig. Fig. 7: Lift the caliper housing off of the mounting bracket

2. If necessary, unfasten the 2 mounting bolts and washers and remove the caliper mounting bracket. Discard the mounting bolts, then clean all of the old bolt adhesive from the bolt hole threads.

Fig. Fig. 8: If necessary, remove and discard the retaining bolts, remove the washers, then remove the mounting bracket-1996 vehicle shown

To install:

9. For 1988-96 vehicles, perform the following:
   1. If removed, position the caliper mounting bracket to the knuckle. Install the washers and mounting bolts and tighten the bolts to 137 ft. lbs. (185 Nm) for 1988-89 vehicles, or to 151-181 ft. lbs. (205-245 Nm) for 1990-96 vehicles.
   2. Install the caliper over the brake rotor and into the caliper mounting bracket. Make sure the shoe lining guiding surfaces are correctly seated in the bracket.

   
   

There are 2 sets of retainer pins in most repair kits. One set is for base calipers and the other is for heavy duty calipers. Make certain the correct retainer pins are installed.

1. Compress the bias springs by applying pressure to the mounting bracket, then install the new retainer pin and circlip.

10. For 1984-87 vehicles, perform the following, as applicable:
    1. If the caliper housing and mounting bracket were removed as an unit, install the assembly, washers and 2 new bracket bolts. Tighten the bracket bolts to 133 ft. lbs. (180 Nm). Recheck the torque on both bolts.
    2. If they were removed separately, install the mounting bracket, if removed, with the washers and 2 new bolts and tighten to 133 ft. lbs. (180 Nm). Recheck the torque on both bolts. Install the caliper housing, using 2 new self-locking bolts and tighten to 22-25 ft. lbs. (30-34 Nm).

    
    
11. If removed, connect the brake hose inlet fitting, 2 new gaskets and the inlet fitting bolt. Tighten the bolt to 30 ft. lbs. (40 Nm).
12. If the inlet fitting was removed, properly bleed the hydraulic brake system.
13. Remove the wheel nuts retaining the rotor, align the marks made earlier and install the tire and wheel assembly.
14. Lower the vehicle and check the brake fluid; add as necessary.

The new bracket mounting bolts come with an adhesive on the threads. You must allow the adhesive to cure for 2 hours after installation before moving the vehicle.

15. Connect the negative battery cable, start the engine and pump the brake pedal slowly and firmly 3 times to seat the shoe and lining assemblies.

1988-96 VEHICLES

See Figures 23, 24, 25 and 26

1. Disengage the parking brake automatic adjuster as follows:
   1. Remove the drivers seat cushion.
   2. Remove the parking brake lever cover and screws.
   3. Using a suitable offset tool, disengage and hold the drive pawl from the drive sector.
   4. Insert a nail or drift through the hole in the anchor plate to retain the drive pawl in the disengaged position.
   5. Move the parking brake lever until it aligns with the lock pawl.
   6. Depress the button on the lever and move the lever to the down position.
   7. Make sure the anchor plate is against the stud on the parking brake lever, if not as specified, repeat the procedure.

   
   

Fig. Fig. 23: Before beginning caliper removal, you must disable the parking brake automatic adjuster-1996 vehicle shown

2. Raise and support the vehicle safely.
3. Mark the relationship between the wheel and axle flange, then remove the tire and wheel assembly.
4. Install 2 lug nuts to hold the brake rotor in place.
5. If the caliper is being completely removed from the vehicle for service or replacement, disconnect the brake line fitting at the caliper by removing the bolt, 2 gaskets and the brake hose inlet fitting. Plug all openings to prevent fluid contamination or loss.

Fig. Fig. 24: Disconnect and plug the fluid line fitting if the caliper is being overhauled or replaced

Do not remove the lever return spring unless the parking brake cable automatic adjuster has been properly disabled.

6. Remove the lever return spring. Discard the spring if the coils are opened.

Fig. Fig. 25: View of the parking brake cable lever and spring

7. Disconnect the brake cable from the lever and bracket.
8. Remove the 2 guide pins bolts and discard.
9. Remove the caliper housing from the brake rotor and caliper mounting bracket.

The caliper mounting brake should only be removed if it is damaged, or if the rotor must be removed.

10. If necessary, unfasten the 2 mounting bolts and washers and remove the caliper mounting bracket. Discard the mounting bolts, then clean all of the old bolt adhesive from the bolt hole threads.

To install:

The new bracket mounting bolts come with an adhesive on the threads. You must allow the adhesive to cure for 2 hours after installation before moving the vehicle.

11. If removed, position the caliper mounting bracket to the knuckle. Install the washers and mounting bolts and tighten the bolts to 137 ft. lbs. (185 Nm) for 1988-89 vehicles, or to 151-181 ft. lbs. (205-245 Nm) for 1990-96 vehicles.

Fig. Fig. 26: Exploded view of the rear caliper mounting bracket-1996 vehicle shown

12. Inspect the guide pins for free movement and replace the pins or boots if damaged or corroded.
13. Install the caliper over the brake rotor and into the mounting bracket.
14. Install 2 new guide pin bolts. Tighten the upper bolt to 26 ft. lbs. (35 Nm) and the lower bolt to 16 ft. lbs. (22 Nm).
15. Install the cable to the bracket and parking brake lever, then install the lever return spring.
16. If removed, connect the brake line fitting, 2 new gaskets and the inlet fitting bolt. Tighten the bolt to 30 ft. lbs. (40 Nm).
17. If the inlet fitting was removed, properly bleed the hydraulic brake system.
18. Enable the parking brake automatic adjuster in the reverse order of the disable procedure and make sure the levers are against the stops on the caliper housing.
19. Remove the 2 nuts securing the rotor to the hub, align the marks made earlier and install the tire and wheel assembly.
20. Lower the vehicle and check the brake fluid level.
21. Connect the negative battery cable, start the engine and pump the brake pedal slowly and firmly 3 times to seat the shoe and lining assemblies.

OVERHAUL

See Figures 27, 28, 29, 30, 31, 32, 33 and 34

Some vehicles may be equipped dual piston calipers. The procedure to overhaul the caliper is essentially the same with the exception of multiple pistons, O-rings and dust boots.

1. Remove the caliper from the vehicle and place on a clean workbench.

CAUTION

NEVER place your fingers in front of the pistons in an attempt to catch or protect the pistons when applying compressed air. This could result in personal injury!

Depending upon the vehicle, there are two different ways to remove the piston from the caliper. Refer to the brake pad replacement procedure to make sure you have the correct procedure for your vehicle.

2. The first method is as follows:
   1. Stuff a shop towel or a block of wood into the caliper to catch the piston.
   2. Remove the caliper piston using compressed air applied into the caliper inlet hole. Inspect the piston for scoring, nicks, corrosion and/or worn or damaged chrome plating. The piston must be replaced if any of these conditions are found.

   
   

Fig. Fig. 27: For some types of calipers, use compressed air to drive the piston out of the caliper, but make sure to keep your fingers clear

Fig. Fig. 28: Withdraw the piston from the caliper bore

3. For the second method, you must rotate the piston to retract it from the caliper.
4. If equipped, remove the anti-rattle clip.

Fig. Fig. 29: On some vehicles, you must remove the anti-rattle clip

5. Use a prytool to remove the caliper boot, being careful not to scratch the housing bore.

Fig. Fig. 30: Use a prytool to carefully pry around the edge of the boot ...

Fig. Fig. 31: ... then remove the boot from the caliper housing, taking care not to score or damage the bore

6. Remove the piston seals from the groove in the caliper bore.

Fig. Fig. 32: Use extreme caution when removing the piston seal; DO NOT scratch the caliper bore

7. Carefully loosen the brake bleeder valve cap and valve from the caliper housing.
8. Inspect the caliper bores, pistons and mounting threads for scoring or excessive wear.
9. Use crocus cloth to polish out light corrosion from the piston and bore.
10. Clean all parts with denatured alcohol and dry with compressed air.

To assemble:

11. Lubricate and install the bleeder valve and cap.
12. Install the new seals into the caliper bore grooves, making sure they are not twisted.
13. Lubricate the piston bore.
14. Install the pistons and boots into the bores of the calipers and push to the bottom of the bores.
15. Use a suitable driving tool to seat the boots in the housing.

Fig. Fig. 33: Use the proper size driving tool and a mallet to properly seal the boots in the caliper housing

16. Install the caliper in the vehicle.
17. Install the wheel and tire assembly, then carefully lower the vehicle.
18. Properly bleed the brake system.

Fig. Fig. 34: There are tools, such as this Mighty-Vac, available to assist in proper brake system bleeding