Disc & Drum Brake System Chevrolet Cab & Chassis C3500

MODEL IDENTIFICATION

Vehicle model can be identified by fifth character of Vehicle Identification Number (VIN), stamped on metal pad on top of left end of instrument panel, near windshield. See MODEL IDENTIFICATION table.

MODEL IDENTIFICATION

DESCRIPTION & OPERATION

Note. Information in this article also applies to vehicles equipped with Anti-Lock Brake System (ABS); however, not all information on ABS is included in this article. See appropriate ANTI-LOCK BRAKE SYSTEM article listed below.

1. «ANTI-LOCK BRAKE SYSTEM - 4-WHEEL»(/chevrolet/cab-chassis-c3500/1989-2000/remont/anti-locktraction-control/#anti-lock-brake-system-4-wheel-c-k-series)
2. «ANTI-LOCK BRAKE SYSTEM - REAR WHEEL»(/chevrolet/cab-chassis-c3500/1989-2000/remont/anti-locktraction-control/#anti-lock-brake-system-rear-wheel)

Note. On vehicles with full-floating axle, axle shaft and hub must be removed to remove brake disc or drum. (Scheme 28) On vehicles with semi-floating axle, brake drum can be removed without removing axle shaft.

BRAKE SHOE ASSEMBLY

Some vehicles are equipped with leading/trailing brakes, identified by adjuster screw hole in backing plate, located above horizontal centerline of rear axle. All other models are equipped with dual-servo brakes, identified by adjuster screw hole at bottom of backing plate.

Brake assembly consists of backing plate, brake shoes, return springs, automatic adjusting assembly and a wheel cylinder.

Automatic adjusting assembly consists of an actuator lever, return spring, actuator link, adjusting screw and spring. Automatic adjustment is accomplished through movement of actuating lever and secondary shoe.

BRAKE WARNING LIGHT

Pressure differential warning switch in combination valve energizes brake warning light on instrument panel when front or rear brakes lose hydraulic pressure. After repairing failed side of hydraulic system, depress brake pedal with moderate to heavy pressure to hydraulically center the piston. This will turn off brake warning light.

CALIPERS (FRONT)

Front brakes are floating caliper or sliding caliper design. (Scheme 31)and (Scheme 32). Rear brakes are sliding caliper design. Caliper is attached to caliper mount. Caliper is mounted to steering knuckle or caliper adapter, depending on application. Caliper assembly slides back and forth in machined cut-outs.

CALIPER (REAR)

The rear disc brakes use a Bendix caliper. The caliper mounts to the anchor plate in a way that allows the caliper to move laterally against the rotor. The caliper is a one piece casting with the inboard side containing a piston bore. A square-cut rubber seal fits in a groove in the piston bore to provide a hydraulic seal between the piston and caliper bore.

Combination Valve

System uses a combination valve to regulate brake system hydraulic pressure. Combination valve, located in brake lines between master cylinder and wheels, has 3 pressure control functions

1. Metering (or hold-off) section of valve limits pressure to front brakes until pressure of rear brake shoe retractor springs is overcome, then allows pressure to front brakes.
2. Proportioning section of valve allows input pressure to rise to predetermined level before allowing output pressure to rear brakes. This prevents rear wheel lock-up on vehicles with light rear wheel loads.
3. By-Pass section of valve ensures full system pressure is applied to rear brakes if front brakes loses hydraulic pressure (or if rear brakes lose hydraulic pressure, full pressure is applied to front brakes).

Combination valve also contains a pressure differential warning switch. See BRAKE WARNING LIGHT under DESCRIPTION & OPERATION .

Height-Sensing Proportioning Valve

Valve senses vehicle load conditions through relative movement between rear axle and body. (Scheme 12) As vehicle load increases (resulting in decreased vehicle height), valve allows higher pressure to rear brakes, resulting in optimum front-to-rear brake pressure balance.

Valves allow input pressure to rise to predetermined level before allowing output pressure to rear brakes. This prevents rear wheel lock-up on vehicles with light rear wheel loads. Valves also incorporate a by-pass feature which ensures full system pressure is applied to rear brakes if front brakes lose hydraulic pressure (or if rear brakes lose hydraulic pressure, full pressure is applied to front brakes).

ROTOR (REAR)

The rear disc brakes use a combination rotor and hub assembly. The rotor is integral with the rear hub. During operation, the rotor turns between the linings and basically free-wheels until the linings begin to apply a clamping action on it. The vented area between the rotor braking surfaces allows for efficient heat dissipation.

BLEEDING BRAKE SYSTEM

Note. On vehicles with ABS, wait 15 seconds between pedal strokes when bleeding brake system. On vehicles with Hydro-Boost, check for air bubbles in power steering fluid reservoir. If air bubbles are present, bleed Hydro-Boost system before bleeding brake system. See BLEEDING HYDRO-BOOST SYSTEM in POWER BRAKE BOOSTER - BENDIX HYDRO-BOOST article in this section.

BLEEDING SEQUENCE

BLEEDING SEQUENCE

MASTER CYLINDER BLEEDING

Note. To prevent air from entering brake system, bench bleed master cylinder before installing.

1. Place master cylinder in soft-jawed vise. DO NOT overtighten vise. Install bleeder tubes in both outlets of master cylinder. (Scheme 10) Fill master cylinder reservoir. Ensure ends of bleeder tubes are submerged in brake fluid.
2. Press and release piston assembly until air bubbles are no longer present in fluid flow. Leave bleeder tubes installed on master cylinder. Install master cylinder.
3. Remove bleeder tubes. Connect brake lines at master cylinder. DO NOT fully tighten brake lines at this time. Slowly press brake pedal to floor and hold. Tighten brake lines. Release brake pedal. Bleed brake system. See «MANUAL BLEEDING»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__manual-bleeding), «PRESSURE BLEEDING»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__pressure-bleeding) or «VACUUM BLEEDING»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__vacuum-bleeding).

Scheme 10

MANUAL BLEEDING

Note. Air tends to cling to caliper walls. When bleeding vehicles with disc brakes, lightly tap caliper to help remove air.

1. Fill master cylinder. Install bleeder hose to bleeder screw at first wheel to be serviced. See BLEEDING SEQUENCE under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) . Submerge other end of hose in glass jar partially filled with brake fluid.
2. Open bleeder screw 3/4 - 1 turn. Slowly press brake pedal to floor. Note fluid flow. Close bleeder screw. Release pedal. Repeat procedure until air bubbles are no longer present in fluid flow.

PRESSURE BLEEDING

Note. Air tends to cling to caliper walls. When bleeding vehicles with disc brakes, lightly tap caliper to help remove air.

1. Retain hold-off valve stem of combination valve using Valve Retainer (J-23709). (Scheme 11) This allows brake fluid to flow through combination valve and entire system during bleeding.
2. Clean master cylinder cap and surrounding area. Remove cap. With pressure tank at least 1/2 full, connect pressure bleeder to master cylinder with adapters. Attach bleeder hose to first bleeder valve to be serviced. See BLEEDING SEQUENCE under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system).
3. Place other end of hose in glass jar partially filled with brake fluid so end of hose is submerged in fluid. Open release valve on pressure bleeder. Set pressure bleeder to 20-25 psi (1.4-1.8 kg/cm 2 ) or pressure specified by equipment manufacturer.
4. Open bleeder screw 3/4 - 1 turn and note fluid flow. Close bleeder screw when no air bubbles are present in fluid flow. Repeat procedure on remaining wheels in proper sequence.
5. Check brake pedal operation. Remove pressure bleeder. Remove valve retainer from hold-off valve. Refill master cylinder reservoir, if necessary.

Scheme 11

VACUUM BLEEDING

Note. Air tends to cling to caliper walls. When bleeding vehicles with disc brakes, lightly tap caliper to help remove air.

1. Fill master cylinder reservoir. Install vacuum bleed equipment to first bleeder valve to be serviced. See BLEEDING SEQUENCE under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) .
2. Open bleeder valve 3/4 - 1 turn. Press vacuum pump to draw fluid into reservoir jar until no air bubbles are present in fluid flow. Close bleeder screw. Repeat procedure on remaining wheels in sequence.

Note. If front wheel lock-up is experienced during braking when vehicle is near maximum GVWR, adjust height-sensing proportioning valve.

1. Ensure rear axle is hanging free and valve is securely bolted to frame when lever is attached to valve before height-sensing proportioning valve is adjusted. (Scheme 12)
2. Raise and support vehicle. Remove nut and lever assembly from valve. Rotate valve shaft to allow installation of plastic adjustment gauge No. GM 15592484. Seat "D" shaped center hole over valve shaft. Gauge must be positioned in valve mounting hole.
3. Install lever assembly to valve shaft with a "C" clamp or locking pliers to seat lever nylon bushing on serrated valve shaft. DO NOT install lever using attaching nut. Doing so can result in improper valve adjustment.
4. Install valve shaft nut and tighten to 80 INCH lbs. (9 N.m). Cut tang from body of adjustment gauge, and allow valve to rotate freely. Lower vehicle and test brakes.

Scheme 12

Vehicles With Leading/Trailing Brakes

1. Raise and support rear of vehicle. Remove rear wheels. Remove brake drums. Rotate parking brake adjusting screw until clearance between brake drum and shoes is .010-.020" (.25-.51 mm). Use brake drum diameter gauge to determine clearance.
2. Ensure stop on parking brake lever is in contact with edge of brake shoe web. If parking brake cable is holding stops off of shoe web, loosen cable adjusting nut. Tighten cable adjusting nut until lever stop begins to move off of shoe web.
3. Loosen cable adjusting nut until lever stop moves back toward lever stop and barely contacts the stop. Clearance should be no more than .020" (.51 mm) between lever stop and shoe web.
4. Install brake drums and wheels. Apply and release service brake pedal 30-35 times with normal pedal force, pausing about one second between pedal applications. Apply parking brake pedal 6 notches from fully released position.
5. Rear wheels should not be able to be rotated. Release parking brake and ensure wheels rotate freely. Lower vehicle.

Vehicles with Transmission-Mounted Parking Brake

1. Remove clevis pin from lever assembly. (Scheme 13) Apply parking brake pedal 4 notches from fully released position.
2. Using small length of cable or chain and a turnbuckle, install Spring Scale (J-35999) between lever assembly and vehicle frame. Tighten turnbuckle until spring scale indicates 50 lbs. (22.7 kg).
3. Loosen clevis nut (at cable end). Turn clevis until clevis pin slides freely into lever assembly with all slack removed from cable. Install clevis pin and retain with a cotter pin. Tighten clevis nut. Remove spring scale. Release parking brake.

Scheme 13

Vehicles With Dual-Servo Brakes

Raise and support vehicle. Loosen parking brake cable adjusting nut. Apply parking brake pedal 4 notches from fully released position. Tighten adjusting nut until wheels rotate forward with moderate drag. Release parking brake and ensure wheels rotate freely. Lower vehicle.

Brake shoe adjustment is accomplished by adjusting parking brake. See PARKING BRAKE under ADJUSTMENTS.

With Cruise Control

Depress and hold brake pedal. Pull lever on stoplight switch back to its stop. (Scheme 14) Pull brake pedal against pedal stop. Release brake pedal. Switch is adjusted if brake lights do not come on with pedal released.

Scheme 14

Electrical Circuit

Disconnect wire from switch terminal on combination valve. Connect wire to ground. Turn ignition on. If brake warning light does not come on, repair brake warning light bulb or wiring circuit. If light operates, brake warning light electrical circuit is okay.

Warning Light Switch

1. Fill master cylinder reservoir. Attach bleeder hose to bleeder screw at either rear wheel. Immerse other end of hose in container of brake fluid. Turn ignition on.
2. While depressing brake pedal, open bleeder screw (close bleeder screw before releasing pedal). On all models except Astro and Safari, if light comes on, go to step 3). If light does not come on, switch is defective; replace combination valve.
3. Close bleeder screw. Depress brake pedal with moderate to heavy pressure. If light goes out, switch is okay. If light stays on, switch is defective, replace combination valve. Repeat test on front brake system. System should function in same manner as rear.

BRAKE LINING INSPECTION (DISC BRAKES)

Inspect the brake linings every 6,000 miles and any time the wheels are removed. Check both ends of the outer lining by looking in at each end of the caliper. These are the points where the highest rate of wear normally occurs. At the same time, check the thicknessof the inner lining to make sure it has not worn prematurely. Some inboard shoe and linings have a thermal layer against the shoe, integrally molded with the lining. This extra layer should not be confused with uneven inboard-outboard lining wear. Look down through the inspection hole in the top of the caliper to view the inner lining. Replace shoe and lining assemblies whenever the thickness of any lining is worn to within .030" (.76 mm) of the shoe. Replace riveted shoe and lining assemblies when the lining is worn to within .030" (.76 mm) of any rivet head. Always replace disc brake shoe and lining assemblies as a complete axle set. Check the flatness of the linings. Place the inboard and outboard lining surfaces together and check for a gap between the surfaces. This gap should be no larger than .005" (.13 mm) at the center of the lining surfaces. This applies to new or used shoe and lining assemblies. The shoe and lining assemblies have a wear indicator that makes noise when the linings are worn and need replacement.

Scheme 15

Scheme 16

REFINISHING BRAKE ROTORS (DISC BRAKES)

It is not necessary to refinish brake rotors when doing routine brake maintenance such as replacing brake shoe and lining assemblies. Refinish rotors only under the following circumstances

1. There is complaint of brake pulsation.
2. There are heat spots or excessive scoring.

Brake rotors have a minimum thickness cast into them. This dimension is the minimum wear dimension and not a refinish dimension. Do not use a brake rotor that will not meet the dimensions shown in the specifications chart after refinishing. A rotor that is too thin will not have the proper heart transfer capabilities. Replace it with a new rotor. Accurate control of rotor tolerances is necessary for the proper performance of disc brakes. Precision equipment should be used for machining. Service machining equipment on a regular basis. Always use sharp cutting tools or bits and use only replacement cutting bits recommended by the equipment manufacturer. Always use vibration dampening attachments when refinishing brake surfaces. They allow for a better surface finish.

Locate the deepest score and turn the rotor micrometer knobs until the tool bit bottoms out at the deepest point of the score. Zero the scale and back out the tool bits. Advance the cutter hand-wheel until the bits have cleared the inner edge of the rotor face. Adjust the micrometer knobs for approximately .005" (.0127 mm) more than the first reading. This will ensure clearing the rotor in one cut. It is very important that you make the rotor surface non-directional by dressing the rotor surfaces with a sanding disc power tool such as Ammco 8350 Safe Swirl Disc Rotor Grinder using 120 grit aluminum oxide sandpaper. Sand each rotor surface using moderate pressure for a minimum of 60 seconds. An alternate method is to use a sanding block with 150 grit aluminum oxide sandpaper. With the rotor turning approximately 150 RPM, sand each rotor surface using moderate pressure for a minimum of 60 seconds. After sanding the rotor clean with brake cleaner.

The finished rotor surface should be as close to that of a new rotor as possible. Failure to obtain the best possible rotor finish can affect initial braking performance.

Scheme 17

Scheme 18

Rotor Tolerance & Surface Finish

Tolerances of the braking surfaces for flatness, parallelism and lateral runout are closely held. The maintenance of close tolerances on the shape of the breaking surfaces is necessary to prevent brake roughness or pulsation. The surface finish must be held to a specific range of 60 Ra roughness or less. The control of the surface can improve lining life. Light scoring of the rotor surfaces not exceeding 1.5 mm (0.06 in.) in depth is normal and not detrimental to brake operation.

Thickness Variation Check

Check thickness variation by measuring the rotor thickness at four or more points around the circumference of the rotor. Use a micrometer calibrated in ten-thousands of an inch. Make all measurements at the same distance in from the edge of the rotor. A rotor measuring thicker than .0005" (.013 mm) can cause pedal pulsation and/or front end vibration during brake applications. A rotor like this should be refinished or replaced.

Lateral Runout Check

The best way to check lateral runout is with the wheels still installed on the vehicle. This gives a much more accurate reading of the total indicated runout under real braking conditions. If equipment is not available to perform the check with the wheels installed, the next best reading can be made with the wheels removed but the caliper still installed.

1. Clean rotor surface. If the wheel must be removed, reinstall the wheel nuts to retain the rotor. Tighten the wheel nuts to the correct torque specification following the wheel nut tightening sequence.
2. Fasten a dial indicator to the steering knuckle so the indicator button contacts the rotor surface about .5" (13 mm) from the outer edge.
3. Set the dial indicator to zero.
4. Turn the wheel one complete revolution and observe the runout indicated on the dial.
5. The total indicated runout must not exceed .0003" (.08 mm).
6. If lateral runout is not within specifications, refinish or replace the rotor as necessary. In some cases, excessive lateral runout can be improved by indexing the rotor on the hub one or two bolt positions from the original position. If lateral runout cannot be corrected by indexing the rotor, check the hub and bearing assembly for excessive lateral runout or looseness. If the hub and bearing assembly lateral runout exceeds .0015" (.040 mm), repair or replace the hub and bearing assembly. NOTE: Any time the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surfaces of the wheel bearing flange and rotor. Failure to do so can result in increased lateral runout and brake pulsation.

CALIPER INSPECTION (DISC BRAKES)

With the caliper removed, inspect the inside of the caliper assembly for signs of fluid leakage. If any is found, overhaul the caliper. Inspect the mounting bolts and sleeves for corrosion. Replace any corroded bolts and sleeves. Do not attempt to polish away the corrosion.

BURNISHING LININGS & ROTORS (DISC BRAKES)

After the brake linings are replaced and/or the rotors refinished, the new braking surface should be broken in, or "burnished". To do this, make 20 stops from 30 mph using medium to firm brake pedal pressure. During this procedure, use care to avoid overheating the brakes.

SYSTEM BLEEDING

1. Place transmission in Park to set control valve in Park mode. Start engine. Turn steering wheel from stop to stop to bleed power steering system. Place transmission in Neutral.
2. Open bleed screw on actuator until fluid flow is free of air, then close bleed screw (bleed screw is near fluid hose connection, on top of actuator). Loosen exhaust line fitting (port EC) at control valve. (Scheme 10) Place transmission in Park. Allow small amount of fluid to bleed from fitting, then tighten fitting.
3. Cycle the system. If noisy, repeat bleeding procedure. Check power steering fluid level with transmission in Neutral and parking brake applied manually. Fluid level should be 7.12" (180.9 mm) from top of reservoir.

FRONT BRAKE CALIPER

Note. For front disc pad removal and installation, perform FRONT BRAKE CALIPER removal and installation procedures but do not disconnect brake hose from caliper (hang caliper out of way with wire). Replace all pads on an axle if wear indicator on any pad contacts rotor or if pad is worn to within 1/32" (.8 mm) of pad backing.

Removal (Floating Caliper)

1. Remove two-thirds of brake fluid from master cylinder. Raise and support vehicle. Remove wheel. Using "C" clamp or large pliers, compress caliper piston until it bottoms in its bore.
2. Disconnect brake hose from caliper. Remove caliper guide pins. (Scheme 31) Remove caliper. Remove pads from caliper. Note retainer spring on inner pad (some models) and remove if replacing pads.

Installation (Floating Caliper)

1. Remove caliper sleeves from caliper. (Scheme 31) Apply silicone grease to outer diameter of caliper sleeves and inner diameter of bushings. Insert caliper sleeves into bushings.
2. Install retainer spring on inner pad (if removed). Install pads in caliper. Install caliper. Install guide pins and tighten to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__torque-specifications).
3. Connect brake hose to caliper and tighten hose bolt to 32 ft. lbs. (43 N.m). Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system).
4. If outer pads are equipped with locking ears, bend ears toward caliper until ears touch caliper. This prevents movement of outer pad in caliper. (Scheme 19) Install wheel.

Scheme 19

Removal (Sliding Caliper)

1. Remove two-thirds of brake fluid from master cylinder. Raise and support vehicle. Remove wheel. Using "C" clamp or large pliers, compress caliper piston until it bottoms in its bore.
2. Disconnect brake hose from caliper. Remove caliper support key bolt. (Scheme 32) Using hammer and brass punch, drive out caliper support key and spring. Remove caliper. Remove inner and outer pads.

Installation (Sliding Caliper)

1. Using wire brush, clean corrosion from machined ways on caliper and caliper mount. Apply silicone grease to these surfaces. Install inner pad and anti-rattle spring on caliper mount. (Scheme 32) Install outer pad in caliper. Place caliper on caliper mount.
2. Install caliper support key and spring. Install caliper support key bolt, ensuring bolt boss fits into circular cutout on caliper support key. Tighten bolt to 15 ft. lbs. (20 N.m).
3. Connect brake hose to caliper and tighten hose bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__torque-specifications). Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system). Install wheel.

Removal (2WD Vehicles)

Remove brake caliper ( DO NOT disconnect brake hose). See FRONT BRAKE CALIPER under REMOVAL & INSTALLATION. Remove grease cap from end of hub. Remove cotter pin, nut, washer and outer bearing. Remove rotor and hub assembly.

Installation (2WD Vehicles)

1. Clean and pack wheel bearings. Install rotor and hub assembly. Install outer bearing, washer and nut. Tighten nut to 12 ft. lbs. (16 N.m) while rotating rotor and hub assembly. This seats bearings.
2. Back off nut until it just begins to loosen. Finger-tighten nut. Back off nut until hole in spindle aligns with hole in nut ( DO NOT back off more than 1/2 of a flat). Install new cotter pin, bend ends over and ensure ends will not contact grease cap when installed. To complete installation, reverse removal procedure.

Removal & Installation (4WD Vehicles - K1500 & K2500)

Remove brake caliper ( DO NOT disconnect brake hose). See FRONT BRAKE CALIPER under REMOVAL & INSTALLATION. Remove rotor. To install, reverse removal procedure.

Removal (4WD Vehicles - K3500)

Remove brake caliper. ( DO NOT disconnect brake hose). See FRONT BRAKE CALIPER under REMOVAL & INSTALLATION. Remove axle shaft nut. Remove hub and bearing assembly retaining bolts. Remove hub/bearing and rotor assembly using wheel puller. (Scheme 20)

Installation (4WD Vehicles)

Install hub and rotor assembly. Install hub and bearing retaining bolts and tighten to 133 ft. lbs. (180 N.m). Install axle shaft nut and tighten to 173 ft. lbs. (233 N.m). To complete installation, reverse removal procedure.

Scheme 20

REAR BRAKE CALIPER

Note. For rear disc pad removal and installation, perform REAR BRAKE CALIPER removal and installation procedures but DO NOT disconnect brake hose from caliper (hang caliper out of way with wire). Replace all pads on an axle if wear indicator on any pad contacts rotor or if pad is worn to within 1/32" (.8 mm) of pad backing.

Removal

1. Remove two-thirds of brake fluid from master cylinder. Raise and support vehicle. Remove wheel. Using "C" clamp or large pliers, compress caliper piston until it bottoms in its bore.
2. Disconnect brake hose from caliper. Remove caliper support key bolt. (Scheme 32) Drive out caliper support key and spring. Remove caliper. Remove inner and outer pads.

Installation

1. Clean corrosion from machined ways on caliper and caliper mount. Apply silicone grease to these surfaces. Install inner pad and anti-rattle spring on caliper mount. Install outer pad in caliper. Install caliper.
2. Install caliper support key and spring. Install caliper support key bolt, ensuring bolt boss fits into circular cutout on caliper support key. Tighten bolt to 15 ft. lbs. (20 N.m).
3. Connect brake hose to caliper and tighten hose bolt to specification. See «TORQUE SPECIFICATIONS»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__torque-specifications) . Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) . Install wheel.

1. Remove two-thirds of the brake fluid from master cylinder. Raise vehicle and support with safety stands. Mark relationship of wheel to hub. Remove wheel.
2. Position a C-clamp and tighten until piston bottoms in bore. (Scheme 23) Remove C-clamp. Remove brake hose.
3. Remove bolt. Support key and spring. Use a brass punch and a hammer to drive the support key out. (Scheme 25) Remove caliper assembly.

Inspection

Inspect inside of the caliper assembly for signs of fluid leakage. If any is found, rebuild or replace caliper.

1. Lubricate caliper and anchor plate sliding surfaces with Aeroshell Grade 5 lubricant or equivalent.
2. Install caliper assembly. Install spring and support key. Use a brass punch and hammer to drive the support key in place. (Scheme 24) NOTE: Make sure the brake hose is not twisted or kinked after installation. Damage to the hose could result.
3. Install bolt. The boss on the bolt must fit into the circular cutout in the key. Tighten the bolt to 15 ft. lbs. (20 N.m).
4. Install brake hose. Tighten brake hose to 33 ft. lbs. (45 N.m). Bleed system.

Scheme 21

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Caliper & Anchor Plate Wear Adjustments (Disc Brakes)

Bendix calipers have oversize replacement keys available to compensate for wear at the caliper to anchor plate to contact points. The keys are identified by marks. If wear is excessive, a rattle sound can be heard from the front brake area. Use the following procedure to measure and correct this condition.

1. Remove caliper. (Scheme 27) Clean surfaces with a wire brush. Smooth any deep nicks with a file.
2. Measure caliper contact surface for wear. Measure caliper to anchor plate wear. Install caliper.

Scheme 27

1. Remove the caliper. Suspend the caliper. (Scheme 26) NOTE: Do not allow calipers to hang from the flexible hoses. Doing so can damage the hoses.
2. Remove inboard lining, anti-rattle spring and outboard lining.

1. Inboard lining and anti-rattle spring. Install outboard lining.
2. Install caliper assembly. NOTE: Make sure the brake hose is not twisted or kinked after installation or damage to the hose could result. WARNING: Before moving the vehicle, pump the brake pedal several times to make sure it is firm. Do not move vehicle until a firm pedal is obtained. Check the brake fluid level in the master cylinder after pumping the brakes.

Removal (9 3/4" & 10 1/2" Full-Floating Axle)

1. Raise and support vehicle. Remove brake caliper ( DO NOT disconnect brake hose). See «REAR CALIPER (DISC BRAKES)»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) under REMOVAL & INSTALLATION. Remove bolts from end of axle shaft.
2. Lightly tap axle shaft flange with soft hammer to loosen shaft. Grip rib on axle shaft flange with locking pliers. Twist axle shaft to start shaft removal. Pull axle shaft from axle housing.
3. Bend lock washer tab away from lock nut. Using Wheel Bearing Nut Wrench (J-2222-C), remove lock nut. Remove lock washer. Remove adjusting nut and washer. Remove hub and rotor assembly.

1. Install hub and rotor assembly. Install washer and adjusting nut. Using Wheel Bearing Nut Wrench (J-2222-C), tighten adjusting nut to 50 ft. lbs. (68 N.m) while turning hub and rotor assembly.
2. Back off adjusting nut and tighten to 30-40 ft. lbs. (41-54 N.m) while turning hub and rotor assembly. Back off adjusting nut 135-150 degrees. Install lock washer and lock nut finger tight. Bend lock washer tab over adjusting nut flat at a minimum angle of 30 degrees.
3. Tighten lock nut to 65 ft. lbs. (88 N.m) minimum. Bend lock washer tab over lock nut flat at a minimum angle of 60 degrees. To install remaining components, reverse removal procedure.

Removal & Installation (Semi-Floating Axle)

Ensure parking brake is released. Raise and support rear of vehicle. Remove wheel. Remove brake drum (if necessary, back off adjuster wheel before removing brake drum). To install, reverse removal procedure. Adjust rear brake shoes. See REAR BRAKE SHOES under ADJUSTMENTS.

Removal (Full-Floating Axle)

1. Ensure parking brake is released. Raise and support rear of vehicle. Remove wheel. Remove bolts from end of axle shaft. (Scheme 28)
2. Lightly tap axle shaft flange with soft hammer to loosen shaft. Grip rib on axle shaft flange with locking pliers. Twist axle shaft to start shaft removal. Pull axle shaft from axle housing.
3. Remove retaining ring and key. Using Wheel Bearing Nut Wrench (J-2222-C), remove adjusting nut. Remove washer. Remove hub and brake drum assembly (if necessary, back off adjuster wheel before removing brake drum).

Scheme 28

1. Apply light coat of bearing lubricant to axle tube. Install hub and brake drum assembly. Install washer and adjusting nut. Using Wheel Bearing Nut Wrench (J-2222-C), tighten adjusting nut 50 ft. lbs. (68 N.m), while turning hub and rotor assembly.
2. Back off adjusting nut until just loose, then tighten until nut's inboard face contacts outer bearing cone shoulder (torque on nut MUST be zero or finger-tight).
3. Insert key into adjusting nut slot. If slot is in alignment with axle spindle keyway, loosen nut slightly but not more than one slot to align key. Install retaining ring. Install axle shaft and wheel. Lower vehicle.

REAR BRAKE SHOES

Note. For rear brake shoe removal and installation (Scheme 33) DO NOT interchange left and right adjusting screw assemblies as one side is right-hand thread and other is left-hand thread.

Removal & Installation

Remove rear brake shoes. See REAR BRAKE SHOES under REMOVAL & INSTALLATION. Disconnect brake line from wheel cylinder. Remove brake cylinder retaining bolts and brake cylinder. To install, reverse removal procedure. Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under BLEEDING BRAKE SYSTEM .

1. With engine off, press brake pedal several times to release vacuum in power brake unit. Clean dirt and grease from master cylinder brake line fittings. Disconnect brake lines from master cylinder and plug line ends.
2. On vehicles with combination valve and bracket attached to master cylinder mounting studs, remove combination valve and bracket. On vehicles without power brake unit, disconnect brake pedal push rod at brake pedal. On all vehicles, remove master cylinder retaining nuts and master cylinder.

1. Bench bleed master cylinder before installing. See MASTER CYLINDER BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) . Position master cylinder on mounting studs. Position combination valve and bracket on mounting studs (if applicable). Loosely install master cylinder retaining nuts. Connect brake lines to master cylinder but DO NOT tighten.
2. Tighten master cylinder retaining nuts. Tighten brake lines. Connect brake pedal push rod (if disconnected). Fill fluid reservoir. Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) .

POWER BRAKE BOOSTER

Note. For Hydro-Boost removal and installation, see POWER BRAKE BOOSTER - BENDIX HYDRO BOOST article in the BRAKES Section.

1. Remove master cylinder. See «MASTER CYLINDER»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) under REMOVAL & INSTALLATION. Ensure no brake fluid contacts ABS control unit (if equipped) or related electrical connectors and wiring.
2. Disconnect vacuum hose from booster. Disconnect booster push rod from brake pedal. Remove booster mounting nuts from inside vehicle. Remove booster and gasket.
3. To install, reverse removal procedure. Bleed brake system if lines were disconnected from master cylinder. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system) .

1. Raise vehicle by frame, allowing rear axle to hang free. Remove bracket that covers valve. Remove nut and lever from valve shaft. (Scheme 12) Clean area around brake line fittings at valve. Disconnect brake lines from valve. Remove valve-to-frame bolts and valve.
2. To install, reverse removal procedure, ensuring rear axle is hanging free and valve is securely bolted to frame when lever is attached to valve (this ensures correct valve adjustment). Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under «BLEEDING BRAKE SYSTEM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system__bleeding-brake-system).

Disconnect brake warning light electrical connector from combination valve switch. Disconnect brake lines from valve. Cap brake line ends. Remove valve mounting bolts. Remove valve.

To install, reverse removal procedure. Bleed brake system. See MANUAL BLEEDING, PRESSURE BLEEDING or VACUUM BLEEDING under BLEEDING BRAKE SYSTEM . Center the brake warning light switch piston by applying moderate to heavy force on brake pedal.

Scheme 29

Scheme 30

1. Raise and support vehicle. Remove wheel and brake drum. Loosen differential cover plate and drain lubricant from axle. Remove cover plate. Remove pinion shaft lock bolt. (Scheme 29)and (Scheme 30).
2. On locking differential models, remove pinion shaft part way. Rotate differential case until pinion shaft contacts axle housing. Using screwdriver, rotate "C" lock until it aligns with thrust block. On all models, push axle shaft toward center of vehicle and remove "C" lock from end of axle shaft.
3. Remove axle shaft from axle housing. Using Seal Remover (J-23689), remove seal from axle housing. Remove bearing using Slide Hammer (J-2619-01) and Bearing Puller (J-23689) on 8 1/2" ring gear, or (J-29712) on 9 1/2" ring gear.

1. Lubricate bearing and seal lips with wheel bearing grease. Fill axle cavity between seal and axle with wheel bearing grease.
2. Using Bearing Installer (J-23690) on 8 1/2" ring gear or (J-29709) on 9 1/2" ring gear, install bearing until installer contacts axle housing. Using Seal Installer (J-21128) on 8 1/2" ring gear or (J-29713) on 9 1/2" ring gear, install seal until even with axle housing.
3. Install axle shaft. Use care not to damage seal. Ensure splines on axle shaft engage with splines on side gear. To install remaining components, reverse removal procedure. Ensure "C" lock is fully seated or positioned in thrust block. (Scheme 29)and (Scheme 30).
4. Install pinion shaft. Install NEW pinion shaft lock bolt and tighten to 25 ft. lbs. (34 N.m). Install differential cover and new gasket. Fill axle with gear lubricant.

REAR AXLE HUB BEARINGS & OIL SEAL (FULL-FLOATING AXLE)

Note. Outer bearing race is seated against a retaining ring inside hub, on inboard side of race. Remove retaining ring from inside of hub before driving out race.

Removal (9 3/4" & 10 1/2" Axle With Disc Brakes)

1. Remove rear hub and rotor assembly. See «REAR BRAKE ROTOR»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) under REMOVAL & INSTALLATION. Using a long drift and hammer, drive out inner bearing race, inner bearing and oil seal from outboard to inboard side of hub.
2. Remove retaining ring from inside of hub, inboard of outer bearing. Using Handle (J-8092) and Outer Bearing Race Remover/Installer (J-24426), drive out outer bearing race from outboard to inboard side of hub.

Installation (9 3/4" & 10 1/2" Axle With Disc Brakes)

1. Clean and pack bearings with Wheel Bearing Lubricant (1051344). Using handle and Bearing Race Installer (J-8608), drive outer wheel bearing race into hub from inboard side of hub (ensure chamfered edge of bearing race installer is facing upward so that it does not contact bearing race).
2. Install retaining ring on inboard side of outer bearing race. Turn hub and rotor assembly inboard side down. Using Outer Bearing Race Remover/Installer (J-24426), seat outer bearing race against retaining ring.
3. Using Inner Bearing Race Remover/Installer (J-24427), drive inner bearing race into hub from inboard side of hub. Install inner bearing. Install new oil seal using Axle Shaft Seal Installer (J-24428).
4. To complete installation, reverse removal procedure. To adjust wheel bearings, follow «REAR BRAKE ROTOR»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) installation procedure under REMOVAL & INSTALLATION.

Removal (9 3/4" & 10 1/2" Axle With Drum Brakes)

1. Remove rear hub and drum assembly. See «REAR BRAKE DRUM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) under REMOVAL & INSTALLATION. Using a long drift and hammer, drive out inner bearing race, inner bearing and oil seal from outboard to inboard side of hub. (Scheme 28)
2. Remove retaining ring from inside of hub, inboard of outer bearing. Using Handle (J-8092) and Outer Bearing Race Remover/Installer (J-24426), drive out outer bearing race from outboard to inboard side of hub.

Installation (9 3/4" & 10 1/2" Axle With Drum Brakes)

1. Clean and pack bearings with Wheel Bearing Lubricant (1051344). Using handle and Bearing Race Installer (J-8608), drive outer wheel bearing race into hub from inboard side of hub (ensure chamfered edge of bearing race installer is facing upward so it does not contact bearing race). (Scheme 28)
2. Install retaining ring on inboard side of outer bearing race. Turn hub and rotor assembly inboard side down. Using Outer Bearing Race Remover/Installer (J-24426), seat outer bearing race against retaining ring.
3. Using Inner Bearing Race Remover/Installer (J-24427), drive inner bearing race into hub from inboard side of hub. Install inner bearing. Install new oil seal using Axle Shaft Seal Installer (J-24428).
4. To complete installation, reverse removal procedure. To adjust wheel bearing, follow «REAR BRAKE DRUM»(/chevrolet/cab-chassis-c3500/1989-2000/remont/mechanical-hydraulic/#disc-drum-brake-system) installation procedure under REMOVAL & INSTALLATION.

OVERHAUL

Note. For overhaul of brake assemblies (Scheme 31)- (Scheme 37).

Scheme 31

Scheme 32

Scheme 33

Scheme 34

Scheme 35

Scheme 36

Scheme 37

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS (EXCEPT REAR DISC CALIPERS)

TORQUE SPECIFICATIONS (REAR DISC CALIPERS)

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DRUM BRAKE SPECIFICATIONS

DRUM BRAKE SPECIFICATIONS

See also:
• ANTI-LOCK BRAKE SYSTEM - 4-WHEEL
• ANTI-LOCK BRAKE SYSTEM - REAR WHEEL
• POWER BRAKE BOOSTER - BENDIX HYDRO-BOOST
• MODEL IDENTIFICATION
• DESCRIPTION & OPERATION
• MANUAL BLEEDING
• PRESSURE BLEEDING
• VACUUM BLEEDING
• BLEEDING BRAKE SYSTEM
• TORQUE SPECIFICATIONS
• FRONT BRAKE CALIPER