Monday, April 8, 2013

Nissan Datsun 1200 1971-73 Brake Repair Guide

Front brakes are either disc or drum type. All models use drum brakes on rear. Master cylinder is tandem piston type. All models are equipped with brake pressure differential valve and warning light. When pressure in one circuit falls, brakes will still function, but warning light comes on to indicate efficiency drop in braking power. Parking brake is connected to rear drum brakes and is activated through parking brake lever located between front seats.

Loosen pedal stopper back off from brake pedal. Measure pedal height from pedal pad to floor; height should be 5.65". If adjustment is required, loosen master cylinder mounting nuts and install or remove shims between cylinder and firewall as required. NOTE - Make sure identical shim pack is used on upper and lower mounting bolts. Tighten pedal stopper until pedal height is 5.57±.078", and tighten lock nut. Pedal free play should then be .197-.591".
Front disc brakes are self-adjusting, therefore, no adjustment in service is required.
Raise and support vehicle, and remove wheel. Using a suitable brake adjusting tool, tighten adjuster wedge clockwise until brake shoe contacts drum. Return adjuster wedge until shoe is slightly separated from drum. Check operation by turning drum and applying brakes; if shoe interferes with drum rotation, readjust.
With rear brakes adjusted, adjust front cable turnbuckle until rear brakes are locked when parking brake lever is pulled sixth ratchet stop. Release parking brake lever and make sure rear wheels turn freely.
Attach a bleed tube to bleeder screw and immerse opposite end of tube in a container partially filled with brake fluid. Pump brake pedal two or three times, keep pedal fully depressed, open bleeder screw and exhaust air, close bleeder screw, and return brake pedal. Repeat operation until air bubbles are no longer seen in discharged fluid. Repeat procedure on remaining brake lines. Bleeding sequence is left-rear, right-rear, left-front, right-front.

Removal - Raise front of vehicle and support in place; remove wheel. Remove clip from retaining pin and brake support pad. Remove retaining pin and spring. Disengage hanger spring and using a suitable pair of pliers pull out friction pads and shims.
Inspecting - With friction pads removed, measure their thickness. Replace any pad that has an over all thickness of less than .240" (6.1 mm). It is recommended that friction pads be replaced as a set to prevent any possibility of uneven braking.
Installation - Clean the caliper cavity and head of cylinder piston. Depress piston until it seats in cylinder and insert friction pads with shims. Ensure shims are properly installed. Install retaining pins in position and insert clips. After pads are installed, apply brake pedal several times to ensure brakes are operational.
Removal - Raise vehicle and suitably support on safety stands; remove tire and wheel. Remove brake friction pads as previously described. Disconnect brake line from wheel cylinder. To ease removal of caliper, remove strut assembly and knuckle arm mounting bolt. Withdraw caliper mounting bolt and separate it from strut assembly.
Installation - To install brake caliper assembly, reverse removal procedure, noting the following: Bleed hydraulic system.
Removal - With caliper removed, remove hub dust cap, cotter pin and nut. Remove hub and rotor assembly with wheel bearing and washer in place. Remove bolts attaching rotor to wheel hub, and separate rotor from hub.
Installation - Reverse removal procedure, tighten rotor-to-hub bolts securely, and adjust wheel bearings.
Removal (Rear) - Raise vehicle and suitably support on safety stands; remove tire and wheel. Loosen parking brake linkage at clevis pin and place out of way. Remove brake drum. Remove shoe retainer and return spring, then lift shoe assembly. Disconnect brake line at bracket on strut assembly. Disengage return spring and remove brake shoes.
Inspecting - Inspect all brake components for damage or excessive wear and replace those found defective. Replace brake lining if it is oil soaked or lining is less than .059" (1.5 mm) thick.
Installation - To install brake lining, reverse removal procedure and note the following: Readjust shoe-to-drum clearance and if necessary, bleed hydraulic system
Removal - Remove clevis pin and separate brake pedal from master cylinder push rod. Disconnect brake line from master cylinder. Remove master cylinder shim noting its position when lifting off cylinder
Installation - To install master cylinder, reverse removal procedures, noting the following: Bleed hydraulic system and check pedal height.

Disassembly - Loosen bleed screw and depress pistons into cylinder. Secure yoke in a vise and tap head with a mallet. Cylinder body can then be removed from yoke, do not allow piston to protrude from cylinder. Remove ring from piston and extract retaining rings from both pistons. Dust boot can now be removed. Depress and remove piston from cylinder. Remove piston seal from cylinder bore. Yoke can be further disassembled
Inspecting - Thoroughly clean all internal parts and check each component for excessive wear or damage. If caliper bore is damaged, or excessively rusted, it must be replaced. If however, slight imperfections are evident, honing will eliminate them. It is recommended to replace all seals when overhauling.
Reassembly - Before assembling components, lightly coat with suitable brake grease. Insert bias ring into piston so round portion of ring fits to bottom of piston. Insert piston into cylinder. Do not fully seat piston. Install dust boot and retaining ring. Install yoke bias ring so it coincides with yoke groove of cylinder. Fit bias spring to yoke so bias spring faces bleeder side of cylinder. With yoke spring inserted in cylinder groove, properly align position of bias spring so groove of spring aligns with yoke. Assemble body-to-yoke, tapping lightly if necessary

Disassembly - Drain all fluid from cylinder and remove stopper bolt. Remove dust cover (boot). Remove snap ring and stopper ring and pull push rod assembly from position. Remove primary and secondary piston NOTE - When disassembling master cylinder, exercise caution not to score, scrape, or in any way damage cylinder bore. Do not remove fluid reservoir unless absolutely necessary.
components along with piston spring. Remove valve cap and valve assembly.
Inspecting - Thoroughly clean all components in approved grade brake fluid. Inspect all components for excessive wear or damage and replace parts as necessary.
Reassembly - Reverse disassembly procedure and note the following: Coat all parts with brake fluid (rubber parts with brake grease) when assembling.