Disc: Other Mazda MX-5 NB

BLEEDING BRAKE SYSTEM

Note. If vehicle is equipped with anti-lock brakes, see ANTI-LOCK - MIATA article for brake bleeding procedure.

BRAKE LINE BLEEDING SEQUENCE

MASTER CYLINDER PUSH ROD

Note. Push rod has an adjustment screw to maintain correct distance between booster push rod and master cylinder piston. If push rod is adjusted too long, it prevents master cylinder piston from completely releasing hydraulic pressure, causing brakes to drag. If push rod is adjusted too short, it causes excessive pedal travel and an undesirable clunk in booster area.

Scheme 5

1. Place Adjustment Gauge (49-F043-001) onto master cylinder. Turn adjusting bolt on adjuster gauge until it contacts bottom of piston. Remove adjuster gauge. Apply 19.7 in. Hg to power brake unit.
2. Invert adjuster gauge and place gauge on power brake unit. Measure clearance between end of adjusting bolt and push rod of power brake unit. (Scheme 5) Clearance should be 0" (0 mm). If not, loosen push rod lock nut and turn push rod to make adjustment. After master cylinder is installed to power brake unit, clearance between push rod and piston should be.004-.016" (.10-.40 mm).

Scheme 6

Scheme 7

Scheme 8

1. Turn adjusting nut on Adjustment Gauge (49-B043-001) clockwise to fully retract gauge rod. Place adjustment gauge onto power brake unit and tighten mounting nuts to 7.3-11 ft. lbs. (9.9-15 N.m). Apply 19.7 in. Hg to power brake unit. Turn adjustment gauge adjusting nut counterclockwise until it just contacts push rod. Ensure gauge rod is seated by pressing lightly on end of gauge rod. Ensure there is no clearance between gauge and push rod.
2. Without disturbing adjusting nut, remove adjustment gauge from power brake booster and place on brake master cylinder. Press lightly on gauge rod to ensure rod is bottomed in master cylinder piston. DO NOT push so hard that piston moves.
3. Note any clearance between adjustment gauge adjusting nut ("B") and adjusting gauge body. Note any clearance between adjustment gauge body and master cylinder ("C"). (Scheme 6) There should be no clearance. To adjust clearance "B", use Rod Holder (49-B043-003) and Socket (49-B043-004), and turn nut to lengthen power booster push rod an amount equal to clearance measured at "B".
4. To adjust clearance "C", measure and record height "D1" of gauge rod at push rod. (Scheme 7) Turn adjusting nut until body sets squarely on master cylinder. Measure and record height "D2" of gauge rod. (Scheme 8) Subtract measurement "D1" from "D2". Using Rod Holder (49-B043-003) and Socket (49-B043-004), turn nut to shorten power booster push rod an amount equal to sum of "D1" minus "D2".

PARKING/EMERGENCY BRAKE

Depress brake pedal several times, and remove cover. Turn adjusting nut to adjust lever stroke. Pull parking brake lever one notch. Ensure parking brake warning light illuminates when brake lever is pulled one notch. Release parking brake. Turn wheels, and ensure brakes do not drag.

BRAKE PEDAL FREE PLAY

With engine off, depress pedal a few times to eliminate vacuum. Depress brake pedal by hand, and check pedal free play. See BRAKE PEDAL FREE PLAY SPECIFICATIONS table.

BRAKE PEDAL FREE PLAY SPECIFICATIONS

Scheme 9

1. Released pedal height is measured from carpet surface on vertical portion of firewall to brake pedal pad center. Height should be 6.73-7.13" (171-181 mm). Disconnect brake switch connector. Loosen lock nut "B", and rotate switch "A" away from pedal. Loosen lock nut "D", and rotate rod "C" to adjust height.
2. To adjust stoplight switch, tighten bolt with lock nut "B" so clearance between bolt for brake switch "A" and pedal stopper is.004-.040" (.10-1.0 mm). (Scheme 9) See «TORQUE SPECIFICATIONS»(ref-2891-S08774246032000041400000). Connect brake switch connector. After adjustment, inspect pedal play and brake light operation.

PROPORTIONING VALVE

Connect 2 pressure gauges and adapters to brake pipes. Bleed brake system. See BLEEDING BRAKE SYSTEM . Measure fluid pressure from master cylinder and to rear brakes. If not as specified, replace proportioning valve. See PROPORTIONING VALVE PRESSURE SPECIFICATIONS table.

PROPORTIONING VALVE PRESSURE SPECIFICATIONS

POWER BRAKE UNIT

1. With engine off, depress brake pedal several times. Press and hold brake pedal, and start engine. If brake pedal moves down slightly immediately after engine starts, power brake unit is operating. If brake pedal does not move as specified, go to next step.
2. Start and run engine for 1-2 minutes. Stop engine. Press brake pedal several times and note if first pedal stroke is long and becomes shorter with subsequent strokes. If first pedal stroke is long and becomes shorter with subsequent strokes, power brake unit is operating. If length of strokes is equal, check valve and vacuum hose between vacuum source and power brake unit. Repair as necessary, and go to next step.
3. Start engine. Press and hold brake pedal. Stop engine. Hold pedal down for about 30 seconds. If brake pedal remains at same height, power brake unit is operating. If pedal height recedes, check valve and vacuum hose between vacuum source and power brake unit. Repair as necessary.

Scheme 10

1. Raise and support vehicle. Remove front wheel assemblies. Remove lower lock pin/guide bolt. (Scheme 10) Remove spring.
2. Remove pads, shims, mounting support and guide plate. Replace pad if lining thickness is less than specified. See «MINIMUM PAD LINING SPECIFICATIONS (FRONT)»(ref-2891-S10129747622000041400000) table.
3. To install, reverse removal procedure. Use Disc Brake Expander (49-0221-600C) to push piston fully inward to install disc pads.

MINIMUM PAD LINING SPECIFICATIONS (FRONT)

REAR AXLE BEARING & OIL SEAL

Note. For information on models with sealed wheel bearings, see appropriate article in SUSPENSION.