Disc & Drum Hyundai Elantra I

DESCRIPTION & OPERATION

Disc/drum brake system is hydraulically operated, using a master cylinder with a single reservoir and 2 outlets. A vacuum assist power brake unit is used on all models. Proportioning valves are used to control anti-skid braking action. Mechanical brake system is self-adjusting. The Sonata master cylinder cannot be rebuilt.

Disc brake pads have built-in wear indicator warning sensors. When brake pad lining is low, sensor will rub against rotor, causing a very notable squealing sound. Sonata models have 4-wheel disc brakes as an option or as standard equipment with Anti-Lock Brake System (ABS).

BLEEDING PROCEDURES

1. Ensure master cylinder reservoir is full of brake fluid. Connect hose to wheel cylinder bleed screw and insert other end of hose in a clear container 1/2 full of brake fluid.
2. Slowly pump brake pedal several times. While depressing brake pedal, loosen bleed screw at left rear wheel cylinder until fluid starts to flow out. Then close bleed screw. Repeat operation until there are no more bubbles in fluid. Tighten bleed screw to specification. See TORQUE SPECIFICATIONS table at end of article. Repeat procedure for right front, right rear and left front wheel cylinder, in that order.

Pedal Height (Brake Not Applied)

Measure pedal height from surface of floor panel to top of brake pedal. (Scheme 1) See BRAKE PEDAL ADJUSTMENT SPECIFICATIONS table. If pedal height is not to specification, back off stoplight switch to where it does not contact pedal arm. Turn stoplight switch until clearance between stoplight switch outer case and pedal arm is.02-.04" (.5-1.0 mm). Tighten lock nut. Recheck pedal height.

Pedal Height (Brake Applied)

Start engine. Apply brake pedal with 110 lbs. (50 kg) force. Measure clearance between floor board and top of brake pedal. If clearance is not to specification, check brake adjustment or check for air in system.

Scheme 1

Pedal Free Play

Check brake pedal free play. If free play is not to specification, adjust brake pedal push rod until correct clearance is obtained. See BRAKE PEDAL ADJUSTMENT SPECIFICATIONS table.

BRAKE PEDAL ADJUSTMENT SPECIFICATIONS

PARKING BRAKE

Note. If parking brake lever is not adjusted to specification, rear brake automatic adjusters will malfunction.

Scheme 2

1. Properly adjusted parking brake lever requires a pull of 44 lbs. (20 kg) to set brake. See PARKING BRAKE STROKE SPECIFICATIONS table for proper stroke (clicks when pulled). If clicks are not as specified, chock wheels to prevent vehicle roll, remove console box and release brake lever. At rear of parking brake lever assembly, adjust cable adjusting nut, allowing enough slack in cables to prevent brake shoe drag. (Scheme 2) PARKING BRAKE STROKE SPECIFICATIONS (1) Application Number Of Clicks Elantra 7-8 Excel & Scoupe 6-7 Sonata 8-9 (1) With 44 lbs. (20 kg) of pressure applied at lever.
2. Loosen parking brake switch mounting bolt. Turn ignition on. Adjust switch until indicator light goes out when brake lever is fully released, and ensure indicator light comes on when lever is pulled up one notch. Release brake. Raise vehicle and turn wheels by hand to ensure rear brakes do not drag.

POWER BRAKE UNIT CHECK VALVE

Remove check valve from power brake unit, leaving engine vacuum hose attached to check valve. Place finger over check valve hole. Start engine. Vacuum should be felt. Leave finger on check valve hole and turn off engine. Vacuum should be maintained after engine is turned off. If vacuum is not as described, check vacuum hose and its connections for leaks, and/or replace check valve.

POWER BRAKE UNIT

1. Run engine 2 minutes; then turn off. Depress brake pedal several times using normal foot pressure. Maximum travel should be obtained on the first application and gradually raise after each following application. If okay, proceed to next step.
2. With engine stopped, depress brake pedal several times. Hold brake pedal down and start engine. If brake pedal goes down slightly, power brake unit is functioning properly.
3. With engine running, depress brake pedal and turn engine off. Hold pedal down for 30 seconds. If pedal height does not change, power brake unit is functioning properly. If all tests are okay, power brake unit is in good condition. If tests results are not as stated, check vacuum hose, vacuum supply and vacuum check valve before replacing power brake unit.

PROPORTIONING VALVE

Note. Manufacturer does not provide testing procedures for Scoupe proportioning valves, mounted on brake master cylinder. (Scheme 14)

Scheme 3

1. Install 2 pressure gauges that will measure to at least 2000 psi (140.6 kg/cm 2 ) to the input and output sides of proportioning valve. (Scheme 3)
2. Measure the input and output pressures with brakes applied. (Scheme 4) If measured pressures are NOT within specification, replace proportioning valve. See PROPORTIONING VALVE TEST SPECIFICATIONS table. DO NOT disassemble proportioning valve.

PROPORTIONING VALVE TEST SPECIFICATIONS

Scheme 4

Removal

1. Raise and support vehicle. Remove front wheel. Remove caliper lower guide bolt or clip and retaining pin (Scoupe). Rotate caliper upward and wire in position.
2. Remove disc pads, shims and springs; noting location and order of assembly for installation reference. Check disc pad minimum thickness wear limit specification. See appropriate DISC BRAKE SPECIFICATIONS table at end of article.

Installation

1. To compress piston back into caliper, install hose onto bleed screw and open bleed screw. Using hammer handle, press piston back into caliper bore. Tighten bleed screw when piston is seated in caliper bore.
2. To complete installation, reverse removal procedure. Tighten caliper guide bolt to specification. See TORQUE SPECIFICATIONS table at end of article. Bleed brake system.

1. Raise and support vehicle. Remove front wheel. Using appropriate hose pinch pliers, clamp off brake hose. Remove both caliper guide bolts or clip and retaining pin (Scoupe).
2. On all models except Scoupe, rotate caliper upward and slide caliper from upper guide pin and remove. On Scoupe, slide caliper inward until free of locating pin. Note locations of disc pads, shims and springs for installation reference. Remove brake hose from caliper and plug all openings.

To install, reverse removal procedure. Tighten caliper brake hose bolt to specification. See TORQUE SPECIFICATIONS table at end of article. Bleed brake system.

1. Raise and support vehicle. Remove front wheel. Remove caliper assembly torque plate bolts (or pins) at steering knuckle. Remove caliper assembly and wire up out of the way.
2. Remove axle shaft hub nut. Using Rotor Puller (09526-11001), press axle shaft out of hub. Remove rotor and hub. (Scheme 5) On all models, check rotor specifications. See appropriate «DISC BRAKE SPECIFICATIONS»(/hyundai/elantra/i-1990-1995/remont/mechanical-hydraulic/#disc-drum__disc-brake-specifications).

Scheme 5

To install rotor, reverse removal procedure. Tighten axle shaft hub nut and caliper assembly torque plate bolts to specification. See TORQUE SPECIFICATIONS .

1. Raise and support vehicle. Remove rear wheel. Remove caliper guide bolts. Remove screw holding trailing shoe support key to anchor plate. (Scheme 11) Move caliper rearward against leading (thin) key and slide trailing shoe key outward to remove. While holding caliper against leading (thin) key, swing front of caliper upward and past anchor plate.
2. Remove outer pad by pushing outer pad inward (off caliper legs). Locator buttons must clear slots in housing before pads can be removed. Slide pad down and off of caliper housing. To remove inner pad, pull pad outward until inner spring clears caliper piston.

1. Install hose to caliper bleed screw and open bleed screw. Using hammer handle, press piston back into caliper bore. Tighten bleed screw when piston is seated in caliper bore. Install pads.
2. To complete installation, reverse removal procedure. Install leading (thin) key toward rear of vehicle. Tighten rear caliper guide bolts to specification. See TORQUE SPECIFICATIONS table at end of article. Bleed brake system.

1. Raise and support vehicle. Remove rear wheel. Remove and plug brake line. Remove caliper guide bolts. Remove screw holding trailing shoe support key to anchor plate. (Scheme 12)
2. Move caliper against leading (thin) key and slide trailing shoe key outward. While holding caliper against leading (thin) key, swing front of caliper up and past anchor plate.

To install, reverse removal procedure. Install leading (thin) key toward rear of vehicle. Tighten rear caliper guide bolts to specification. See TORQUE SPECIFICATIONS table at end of article. Bleed brake system.

1. Raise and support vehicle. Remove caliper assembly from anchor plate. See REAR DISC BRAKE CALIPER under REMOVAL & INSTALLATION. Support caliper assembly to prevent damage to brake hose.
2. Remove set screw from rotor mounting face and remove rotor from axle flange. Check rotor specifications. See appropriate DISC BRAKE SPECIFICATIONS table at end of article.

To install rotor, reverse removal procedure. Install leading (thin) key toward rear of vehicle. Tighten rear caliper guide bolts to specification. See TORQUE SPECIFICATIONS table at end of article. Bleed brake system.

1. Raise and support vehicle. Remove rear wheel. Remove brake drum. If brake drum is difficult to remove, insert 2 metric bolts into threaded holes in brake drum and, alternating from side to side, screw in bolts to remove drum. Drum may also be removed along with hub assembly as described in step 2.
2. Remove grease cap. Remove self-locking nut or remove cotter pin, lock nut, adjusting nut and washer. Remove outer wheel bearing. Remove brake drum and or hub assembly. Using a flat-bladed screwdriver, pry out oil seal. Remove inner wheel bearing. If necessary to remove wheel bearing races, drive out races from opposite side using a brass drift.

1. To install, reverse removal procedure. Tighten axle self-locking nut to specification while rotating wheel. See TORQUE SPECIFICATIONS table at end of article.
2. Check end play using dial indicator. Position indicator plunger tip on axle flange rim nearest spindle. With parking brake off, move drum/hub assembly in and out. Maximum limit of end play allowed is .008" (.20 mm) for Elantra or .004" (.10 mm) for all other models. If end play exceeds limit, replace wheel bearings.
3. Fill grease cap with grease and install cap. Apply and release parking brake lever. Depress and release brake pedal. This will automatically adjust shoe clearance.

Raise and support vehicle. Remove brake drum. Remove automatic adjuster spring and automatic adjuster lever. (Scheme 6)and (Scheme 7). Spread shoes and remove adjuster strut. Remove shoe-to-shoe spring and front shoe hold-down spring. Remove front shoe. Remove rear shoe hold-down spring and parking cable clip at shoe. Remove shoe.

Scheme 6

Scheme 7

Note. The adjuster strut is marked "R" or "L" for right or left side of vehicle.

To install, reverse removal procedure. Apply Lubriplate to all shoe contact points, adjuster assembly and parking brake attachment. Retract adjuster strut all the way in. To complete installation, reverse removal procedure. Apply and release parking brake lever. Depress and release brake pedal. This will automatically adjust shoe clearance.

1. Remove fluid level sensor harness connector. Remove brakelines and proportioning valves from master cylinder. On Elantra and Excel, proportioning valve is not attached directly to master cylinder. Plug fitting holes in master cylinder to prevent brake fluid spillage on painted or plastic surfaces.
2. On all models, remove master cylinder from power brake unit. Drain master cylinder brake fluid into a container. Separate reservoir from housing and clean out reservoir. (Scheme 13)or (Scheme 14).

1. On Scoupe, adjust clearance between power brake unit push rod and master cylinder piston before installing master cylinder. Distance from front surface of power brake unit to front of push rod should be.220-.235" (5.59-5.97 mm). (Scheme 8)
2. Push rod adjustment is not necessary on other models. To complete installation of master cylinder, reverse removal procedure. After installation, adjust pedal height. See ADJUSTMENTS. Bleed brake system.

Scheme 8

POWER BRAKE UNIT CHECK VALVE REPLACEMENT

Note. Test check valve before removal. See POWER BRAKE UNIT CHECK VALVE under TESTING.

Removal & Installation (Elantra & Excel)

Remove hose clamps from both ends of check valve. Remove check valve. To install, coat both ends of check valve with non-hardening sealer. Install check valve in vacuum hose with arrow pointing toward intake manifold hose. Install check valve clamps. (Scheme 9)

Scheme 9

Removal & Installation (Scoupe & Sonata)

Remove check valve from power brake unit. Remove vacuum hose clamp and remove valve from hose. Install new valve into vacuum hose and install clamp. Perform testing sequence to ensure correct valve operation. See POWER BRAKE UNIT CHECK VALVE under TESTING. If valve operates as described, coat valve hose barb with non-hardening sealer and install into power brake unit.

Remove brake master cylinder. See MASTER CYLINDER under REMOVAL & INSTALLATION. Disconnect check valve/vacuum hose from power brake unit. From inside vehicle, disconnect power brake unit actuating rod at brake pedal. Remove 4 nuts attaching power brake unit to firewall. Remove power brake unit.

To install, reverse removal procedure. On Scoupe models, adjust power brake unit push rod to specification. See MASTER CYLINDER under REMOVAL & INSTALLATION. Bleed brake system.

FRONT & REAR DISC BRAKE CALIPER

Disassembly

Remove caliper piston boot. Place a narrow wooden block between piston and caliper that will allow piston to clear its bore and not be damaged by caliper end when removed. Using low pressure compressed air, apply air into caliper fitting hole to force piston out of caliper. Remove wood block and piston. Remove dust boot and piston seal (use small flat bladed screwdriver if necessary).

Cleaning & Inspection

Clean all parts with water first, then clean metal parts with alcohol. DO NOT expose rubber parts to alcohol or damage to parts will occur. Inspect caliper bore and piston for wear, damage or rust. Light rust in caliper bore can be removed with crocus cloth or small wire wheel. Replace piston if rusty. DO NOT reuse caliper piston seal and/or dust boot. Replace any worn or defective parts.

Reassembly

1. Apply brake caliper lubricant to piston seal and install piston seal into caliper bore groove. Apply caliper lube to piston, cylinder bore and inside dust boot. Install dust boot onto piston.
2. Position piston with boot into caliper bore and install dust boot lip into cylinder groove. Press piston into caliper bore, ensuring boot remains in groove. Apply brake caliper lube or rubber grease to guide sleeve and inner portion of sleeve boots, and install caliper. (Scheme 10), (Scheme 11), (Scheme 12) or (Scheme 13).

Scheme 10

Scheme 11

Scheme 12

Scheme 13

MASTER CYLINDER

Note. Master cylinder for Sonata models cannot be disassembled or overhauled and must be replaced if found defective.

Disassembly (Excel & Scoupe)

Place cylinder mounting flange in a soft-jawed vise. Remove dust boot and snap ring. Withdraw primary piston assembly, secondary piston assembly and secondary return spring from master cylinder.

Note. DO NOT disassemble master cylinder piston assemblies.

Inspect master cylinder bore and piston for wear or other damage. Check clearance between cylinder bore and piston. Clearance should not exceed .006" (.15 mm). If any parts are found to be worn or defective, replace part or replace master cylinder as complete assembly.

To reassemble, reverse disassembly procedure. Before reassembly, apply brake caliper lubricant or brake fluid to all parts (except boots). Ensure return port is not blocked by piston cup when piston is at return position.

Scheme 14

Scheme 15

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS (FRONT)

DISC BRAKE SPECIFICATIONS (REAR)

DRUM BRAKE SPECIFICATIONS

DRUM BRAKE SPECIFICATIONS

See also:
• DISC BRAKE SPECIFICATIONS
• TORQUE SPECIFICATIONS