Mazda RX-7 Disc Brakes - bleeding, pedal height, pads, etc.

Mazda RX7 1993-1995 FD3S


All models use hydraulic-operated brake system with a tandem master cylinder, proportioning valve and a power brake unit. All models are equipped with front disc brakes and either rear disc or rear drum brakes.

BLEEDING BRAKE SYSTEM

BRAKE LINE BLEEDING SEQUENCE

• Mazda RX7 1993-1995: Longest Line First, bleed master cylinder and RABS hydraulic unit before bleeding wheel cylinders and calipers.

ADJUSTMENTS

MASTER CYLINDER PUSH ROD

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.

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 88-138 INCH lbs. (9.9-15.6 N.m). Apply 19.7 in. Hg to power brake unit. Turn adjustment gauge adjusting nut counterclockwise until it just contacts master cylinder push rod. Ensure gauge rod is seated by pressing lightly on end of gauge 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 and adjusting gauge body. Note any clearance between adjustment gauge body and master cylinder body. Using Rod Holder (49-B043-003) and Socket (49-B043-004), adjust power brake push rod as necessary to obtain .004-.016" (.1-.4 mm) between adjustment gauge adjusting nut and adjusting gauge body.

PARKING/EMERGENCY BRAKE

1. Depress brake pedal several times. Pull parking brake lever with a force of 22 lbs. (10 kg). If stroke is 7-10 notches, parking brake is properly adjusted. If stroke is not 7-10 notches, raise and support rear of vehicle. Release parking brake lever.
2. Rotate cable adjusting nut at lever end of cable, located under console cover, until stroke is within specification. Ensure rear brakes do not drag. Ensure parking brake warning light illuminates when brake lever is pulled one notch.

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. Adjust play by loosening push rod lock nut. Turn push rod until correct free play is obtained. Tighten push rod lock nut to 18-25 ft. lbs. (24-34 N.m).

BRAKE PEDAL FREE PLAY SPECIFICATIONS

• Mazda RX7 1993-1995: .12-.31 (3-8) In. (mm)

BRAKE PEDAL HEIGHT AND STOPLIGHT SWITCH

1. Released pedal height is measured from carpet surface on vertical portion of firewall to pedal pad center. Disconnect stoplight switch electrical connector. Loosen lock nut on stoplight switch. Rotate switch away from pedal. Loosen push rod lock nut. Rotate push rod until correct pedal height is obtained.
2. Adjust pedal free play. Tighten push rod lock nut to 18-25 ft. lbs. (24-34 N.m).
3. Rotate stoplight switch until it contacts pedal and then rotate an additional 1/2 turn. Tighten stoplight switch lock nut 10-13 ft. lbs. (14-18 N.m). Reconnect stoplight switch electrical connector.
4. Applied pedal height is measured from angled portion of firewall (without carpet) to pedal pad center. Start engine. Depress brake pedal with 132 lbs. (60 kg) pressure.
5. Measure applied pedal height. If distance is not as specified, check for air in system, rear brake adjustment (drum brakes) or worn shoes or pads.

BRAKE PEDAL HEIGHT SPECIFICATIONS

• Pedal Released: 6.5-6.9 (165-176) In. (mm)
• Pedal Applied, Minimum height: 3.9 (100) In. (mm)

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TESTING

PROPORTIONING VALVE

1. Connect 2 pressure gauges and adapters to proportioning valve. One to input port and other to output port. Bleed brake system. Depress brake pedal until pressure gauge reads as specified and check output pressure.
2. Depress brake pedal again, applying additional pressure. Recheck output pressure. If output pressure is not as specified, replace proportioning valve.

PROPORTIONING VALVE PRESSURE SPECIFICATIONS

• Mazda RX7 1993-1995:
  • Inlet Pressure psi (kg/cm2 ): 570 (40)
  • Inlet Pressure psi (kg/cm2 ): 850 (60)
  • Outlet Pressure psi (kg/cm2 ): 530-610 (37-43)
  • Outlet Pressure psi (kg/cm2 ): 626-739 (44-52)

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. Run engine for 1-2 minutes. Stop engine. Press brake pedal several times and note if first pedal stroke is longer than subsequent strokes. If first pedal stroke is longer than 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 pedal height 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.

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REMOVAL AND INSTALLATION

FRONT DISC BRAKE PADS

1. Raise and support front of vehicle. Remove front wheel assemblies. Remove "M" clip. See Fig. 1. Remove pad pins. Remove "M" spring. Remove pads and shims. Replace pad if lining thickness is less than specified.
2. To install, reverse removal procedure. Use Disc Brake Expander (49-0221-600C) and an old pad to push piston fully inward to install disc pads. Ensure shims are installed with arrows facing direction of forward rotor rotation.

MINIMUM PAD LINING SPECIFICATIONS (FRONT)

• Mazda RX7 1993-1995: .04 (1.0) In. (mm), Thick

Fig. 1: Exploded View Of Front Disc Brake Assembly

FRONT DISC BRAKE CALIPER

Raise and support front of vehicle. Remove front wheel assemblies and disconnect brake hose. Plug all openings. Remove front disc brake pads.Remove remaining mounting bolt(s). Remove caliper from vehicle. To install, reverse removal procedure. Bleed air from system.

FRONT BRAKE ROTOR

1. Raise and support front of vehicle. Remove front wheel assemblies. Remove front disc brake caliper with brake hose connected. Wire caliper aside. Remove rotor-to-hub screws (if equipped). Remove rotor.
2. Machine rotor if lateral runout exceeds specification. Replace rotor if measured thickness is less than specified minimum thickness. To install, reverse removal procedure.

REAR DISC BRAKE PADS

1. Raise and support rear of vehicle. Remove rear wheel assemblies. Remove lower guide bolt from caliper. Rotate caliper upward and support using wire. Remove "V" spring. Remove pads, shims and guide plates. Replace pad if lining thickness is less than .04" (1.0 mm).
2. To install, reverse removal procedure. Use Disc Brake Piston Wrench (49-FA18-602) to rotate piston clockwise to install disc pads. Ensure grooves in piston are aligned. See Fig. 2.

Fig. 2: Aligning Brake Caliper Piston

REAR BRAKE CALIPER

1. Raise and support rear of vehicle. Remove rear wheel assemblies. Release parking brake and disconnect parking brake cable from caliper. Disconnect brake hose from caliper.
2. Remove guide bolts from caliper. Remove brake caliper from caliper mount. To install, reverse removal procedure. Bleed air from system.

REAR BRAKE ROTOR

1. Raise and support vehicle. Remove rear wheel assemblies. Remove rear brake caliper with brake hose connected. Support caliper using wire. Remove rotor-to-hub screws (if
equipped). Remove rotor.
2. Machine rotor if lateral runout exceeds specification. Replace rotor if measured thickness is less than specified minimum thickness.
3. To install, reverse removal procedure. Check end play at grease cap. If end play exceeds .002" (.05 mm), check lock nut torque or replace wheel bearings.

REAR AXLE BEARING AND OIL SEAL REMOVAL AND INSTALLATION

MASTER CYLINDER

Disconnect fluid level sensor electrical connector at fluid reservoir. Disconnect and plug brake lines at master cylinder to prevent entry of dirt and loss of fluid. Remove nuts attaching master cylinder to power brake unit. Remove master cylinder from vehicle. To install master cylinder, reverse removal procedure. Bleed air from system.

POWER BRAKE UNIT

Remove master cylinder from power brake unit. Disconnect vacuum line at power brake unit. See Fig. 3 . From inside vehicle, remove cotter pin and clevis pin. Separate push rod from brake pedal. Remove power brake unit-to-firewall nuts. Remove power brake unit. To install, reverse removal procedure. Bleed air from system.

Fig. 3: Removing Power Brake Unit (Typical)

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OVERHAUL

Use appropriate illustrations for exploded view of rear caliper assembly and master cylinder. See Fig. 4 through Fig. 5 . Overhaul information for power brake unit is not available at time of publication.

Fig. 4: Exploded View Of Rear Caliper Assembly

Fig. 5: Exploded View Of Master Cylinder

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TORQUE SPECIFICATIONS

• Caliper Guide Bolts (Rear): 46-62 (63-84) Ft. Lbs. (N.m)
• Caliper Mount Bracket Bolts (Rear): 34-49 (46-67) Ft. Lbs. (N.m)
• Front Caliper Mounting Bolt: 58-72 (79-98) Ft. Lbs. (N.m)
• Power Brake Unit Nuts: 14-18 (19-25) Ft. Lbs. (N.m)
• Rear Axle Lock Nut: 131-173 (177-235) Ft. Lbs. (N.m)
• Wheel Lug Nut: 65-87 (88-118) Ft. Lbs. (N.m)
• Wheel Cylinder Mounting Bolt: 88-108 (10-12)INCH Lbs. (N.m)

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DISC BRAKE SPECIFICATIONS

• Front: Maximum lateral runout is .004" (.10 mm).
• Original Thickness: .87 (22) In. (mm)
• Minimum Thickness: .79 (20) In. (mm)
• Rear: Maximum lateral runout is .004" (.10 mm).
• Original Thickness: .79 (20) In. (mm)
• Minimum Thickness: .71 (18) In. (mm)

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Mazda RX-7 1993-1995 FD3S

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