Chrysler Full-Size Trucks 1967-1988 Repair Guide

Master Cylinder

Print

REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4

Except 1979-82 Aluminum Master Cylinder
  1. Use penetrating oil to help loosen the brake lines, then use an open end wrench (preferably a line-wrench) to disconnect them from the master cylinder.
  2.  


WARNING
Cap or plug all openings to prevent system contamination and to minimize fluid loss.

  1. Except on vehicles equipped with power assist brakes, disconnect the master cylinder pushrod from the pedal linkage. On most vehicles you will have to loosen the nut and remove the retaining bolt.
  2.  
  3. Loosen the master cylinder retaining nuts, then support the cylinder and remove the nuts from the studs.
  4.  
  5. Remove the master cylinder from the vehicle. Be careful not to drip brake fluid on any painted surfaces.
  6.  

To install:

Before installing a brake master cylinder it should be bench bled. Plug the ports and refill the master cylinder reservoir(s), then carefully bleed the master cylinder bore of air.



Click image to see an enlarged view

Fig. Fig. 1: Use penetrating oil to help loosen the hydraulic line fittings on the master cylinder

  1. Position the master cylinder over the mounting studs. On master cylinders equipped with external piston linkage, guide the pushrod carefully into position.
  2.  
  3. Install the master cylinder mounting nuts, then tighten to 10 ft. lbs. (13 Nm) for 1967-72 vehicles or to 16 ft. lbs. (21 Nm) for 1973 and later trucks.
  4.  
  5. If applicable, connect the pushrod to the pedal linkage and secure.
  6.  
  7. Remove the plugs and quickly thread the brake tubes to the master cylinder ports. Tighten the fittings sufficiently to begin the brake bleeding procedure.
  8.  
  9. Bleed the master cylinder and the entire hydraulic brake system.
  10.  
  11. Verify that a firm pedal has been obtained before attempting to move the truck.
  12.  



Click image to see an enlarged view

Fig. Fig. 2: Whenever possible, use a line wrench to prevent stripping the brake line fittings



Click image to see an enlarged view

Fig. Fig. 3: You can loosen the master cylinder nuts using a box wrench, but a socket and torque wrench will be necessary for installation.



Click image to see an enlarged view

Fig. Fig. 4: Once all connections, nuts and fittings are removed, carefully withdraw the master cylinder from its mounting

  1. Bleed the brake system.
  2.  

1979-82 Aluminum Master Cylinder

WITHOUT POWER BRAKES
  1. Use penetrating oil to help loosen the brake lines, then use an open end wrench (preferably a line-wrench) to disconnect them from the master cylinder.
  2.  


WARNING
Cap or plug all openings to prevent system contamination and to minimize fluid loss.

  1. Disconnect the stop lamp switch bracket and allow the switch to hang out of the way.
  2.  
  3. Pull the brake pedal backwards to disengage the pushrod from the master cylinder piston. This will require at least 50 lbs. of force. It will also destroy the retention grommet.
  4.  
  5. Remove the master cylinder mounting nuts.
  6.  
  7. Slide the master cylinder straight away from the firewall. Remove all traces of the old grommet.
  8.  

To install:

Before installing a brake master cylinder it must be bench bleed.

  1. When installing the master cylinder, tighten the nuts to 16 ft. lbs. (21 Nm). Moisten a new grommet with water, align the pushrod with the piston and, using the brake pedal, push the pushrod into the piston until it is fully seated. Install the boot.
  2.  
  3. Connect the stop lamp switch, adjust the switch, bleed the brake system.
  4.  

WITH POWER BRAKES
  1. Use penetrating oil to help loosen the brake lines, then use an open end wrench (preferably a line-wrench) to disconnect them from the master cylinder.
  2.  


WARNING
Cap or plug all openings to prevent system contamination and to minimize fluid loss.

  1. Loosen the master cylinder retaining nuts, then support the cylinder and remove the nuts from the studs.
  2.  
  3. Remove the master cylinder from the vehicle. Be careful not to drip brake fluid on any painted surfaces.
  4.  

To install:

Before installing a brake master cylinder it should be bench bled. Plug the ports and refill the master cylinder reservoir(s), then carefully bleed the master cylinder bore of air.

  1. Position the master cylinder over the mounting studs, then install the mounting nuts and tighten to 16 ft. lbs. (21 Nm).
  2.  
  3. Remove the plugs and quickly thread the brake tubes to the master cylinder ports. Tighten the fittings sufficiently to begin the brake bleeding procedure.
  4.  
  5. Bleed the master cylinder and the entire hydraulic brake system.
  6.  
  7. Verify that a firm pedal has been obtained before attempting to move the truck.
  8.  

OVERHAUL



See Figures 5, 6, 7 and 8

1967-78 Trucks
CHRYSLER CAST IRON TANDEM
  1. Clean the outside of the cylinder. Remove the cover and drain the fluid.
  2.  
  3. Loosen the rear piston retainer screw from inside the reservoir, then remove the snapring from the outer end of the cylinder bore. Remove the primary piston.
  4.  
  5. Remove the secondary piston. If the piston sticks in the cylinder, air pressure may be used to remove it. Always use new rubber cups.
  6.  
  7. Note the position of the rubber cups and springs and remove them from the pistons and from the bore.
  8.  
  9. If necessary, remove the tube seats, using a screw threaded into the seat. Unless the seat is damaged, it is not absolutely necessary to remove the seats.
  10.  
  11. Remove the residual pressure valves and springs found under the seats.
  12.  
  13. Clean the inside of the master cylinder with brake fluid or denatured alcohol.
  14.  
  15. Closely inspect the inside of the master cylinder. Polish the inside of the bore with crocus cloth. If there is rust or pitting it will be necessary to use a hone. Discard the master cylinder if scores or pits cannot be eliminated by honing.
  16.  
  17. Do not reuse old rubber parts and be sure to use all the new parts supplied in the rebuilding kit.
  18.  
  19. Before assembly, thoroughly lubricate all parts with clean brake fluid.
  20.  
  21. Replace the primary cup on the front end of the piston with the lip away from the piston.
  22.  
  23. Carefully slide the second seal cup over the rear of the piston and into the second land. The cup lip must face the front of the piston.
  24.  
  25. Slowly work the rear secondary cup over the piston and position it in the rear land. The lip must face to the rear.
  26.  
  27. Slide the retainer cup over the front piston stem with the beveled side facing away from the piston cup.
  28.  
  29. Replace the small end of the pressure spring into the retainer.
  30.  
  31. Position the assembly in the bore. Be sure the cups are not canted.
  32.  
  33. Slowly work the secondary cup over the back of the rear piston with the cup lip facing forward.
  34.  
  35. Position the spring retainer in the center of the rear piston assembly. It should be over the shoulder of the front piston.
  36.  
  37. Position the piston assembly into the bore. Slowly work the cup lines into the bore, then seat the piston assembly.
  38.  
  39. Hold the pistons in the seated position. Insert the piston retaining screw with the gasket, and tighten it securely.
  40.  
  41. Replace the residual pressure valves and spring. Position them in the front outlet and install the tube seats.
  42.  

BENDIX CAST IRON TANDEM
  1. Clean the outside of the cylinder and insert a screw extractor in the tube seat and tighten firmly. Tap gently on the tool and remove the seat.
  2.  
  3. Remove the cover and the gasket and drain the brake fluid from the cylinder.
  4.  
  5. Remove the snapring from the open end of the cylinder. Slide out the washer and carefully remove the primary piston then the secondary piston assembly from the master cylinder.
  6.  
  7. Clean all parts in a suitable solvent and blow dry with compressed air. Wash the cylinder bore with clean brake fluid and check for scoring or pitting. If the cylinder bore walls have light scratches or show signs of corrosion, it can be cleaned with a crocus cloth. Cylinder walls that have deep scratches or scoring may be honed, providing the diameter of the bore is not increased more than 0.002 in. (0.05mm).
  8.  


WARNING
Do not reuse any rubber parts! If you are using a brake cylinder rebuilding kit, use ALL the parts supplied with the kit!

  1. Dip all component parts in clean brake fluid and coat the inside of the bore with brake fluid.
  2.  
  3. Carefully slide the front piston assembly into the cylinder body.
  4.  
  5. Slide the rear piston into the cylinder body.
  6.  
  7. Compress the pistons and install and tighten the front piston retainer screw.
  8.  
  9. Hold the washer in position and install the snapring.
  10.  
  11. Install the residual pressure valve and spring in the outlet port and firmly install the tube seats.
  12.  
  13. Bleed the master cylinder before installation.
  14.  

1979-88 Vehicles
ALUMINUM MASTER CYLINDER
  1. Clean the outside of the master cylinder.
  2.  
  3. Remove the reservoir caps and empty the brake fluid from the reservoir.
  4.  
  5. With the master cylinder in a vise, remove the reservoir from the master cylinder housing by grasping and moving from side to side.
  6.  
  7. Remove the reservoir grommets from the master cylinder.
  8.  
  9. Remove the secondary piston retainer pin from inside the master cylinder housing using a pair of needle nose pliers.
  10.  

This pin is not used on 1983-88 cylinders.

  1. Remove the snapring from the outer end of the cylinder bore and slide the primary piston out of the cylinder bore.
  2.  
  3. Remove the secondary piston by tapping the open end of the master cylinder on the end of a bench. If the secondary piston sticks it may be necessary to use air pressure to force the piston out.
  4.  
  5. Note the position of the cup lips, then remove the cups from the piston.
  6.  
  7. If the brass tube seats are not reusable, replace them using an extractor tool.
  8.  
  9. Wash the inside of the bore with clean brake fluid and check for scoring, pitting or scratches.
  10.  

Do not hone the master cylinder. If any of the above conditions exist, the master cylinder must be replaced.

  1. Dip all components in clean brake fluid and place on a clean shop towel or paper.
  2.  
  3. Install the check flow washer and carefully work the primary cup on the end of the secondary piston with the lip away from the piston.
  4.  
  5. Slide the retainer cup over the front end of the piston followed by the piston spring.
  6.  
  7. Carefully work the secondary piston secondary cup over the rear end of the secondary piston, with the cup lip away from the piston.
  8.  
  9. Keep well lubricated with brake fluid and install the secondary piston assembly into the bore of the master cylinder.
  10.  
  11. Carefully work the second cup over the end of the primary piston with the larger lip of the cup toward the piston.
  12.  
  13. Center the spring retainer of the primary piston on the secondary piston. Push the piston assemblies into the bore up to the primary piston cup. Carefully work the cup into the bore then push the piston in up to the secondary seal. Carefully work the primary cup into the bore, then push in on the piston until seated.
  14.  
  15. Depress the piston with a brass drift or wood dowel and install the snapring.
  16.  
  17. Position the secondary piston retainer pin in the housing and tap or press it until it is firmly seated.
  18.  
  19. Install new tube seats, firmly.
  20.  
  21. Install the reservoir grommets in the master cylinder housing.
  22.  
  23. Lubricate the reservoir mounting area, then with a rocking motion, install the reservoir into the master cylinder housing.
  24.  
  25. Before installation, bench bleed the master cylinder.
  26.  

CAST IRON MASTER CYLINDER
  1. Clean the outside of the cylinder and insert a screw extractor in the tube seat and tighten firmly. Tap gently on the tool and remove the seat.
  2.  
  3. Remove the cover and the gasket and drain the brake fluid from the cylinder.
  4.  



Click image to see an enlarged view

Fig. Fig. 5: Exploded view of a common master cylinder assembly-984-88 cast iron shown master cylinder

  1. Remove the snapring form the open end of the cylinder. Slide out the washer and carefully remove the primary piston then the secondary piston assembly from the master cylinder.
  2.  



Click image to see an enlarged view

Fig. Fig. 6: To disassemble the master cylinder you must first remove the snapring



Click image to see an enlarged view

Fig. Fig. 7: After removing the snapring, you can withdraw the piston assembly



Click image to see an enlarged view

Fig. Fig. 8: Once the piston assembly is removed you can clean and inspect all components for possible reuse

  1. Clean all parts in a suitable solvent and blow dry with compressed air. Wash the cylinder bore with clean brake fluid and check for scoring or pitting. If the cylinder bore walls have light scratches or show signs of corrosion, it can be cleaned with a crocus cloth. Cylinder walls that have deep scratches or scoring may be honed, providing the diameter of the bore is not increased more than 0.002 in. (0.05mm). If the measurement is not below the maximum specification the cylinder must be discarded and replaced with a new master cylinder.
  2.  


WARNING
Do not reuse any rubber parts! If you are using a brake cylinder rebuilding kit, use ALL the parts supplied with the kit!

  1. Dip all component parts in clean brake fluid and coat the inside of the bore with brake fluid.
  2.  
  3. Carefully slide the front piston assembly into the cylinder body.
  4.  
  5. Slide the rear piston into the cylinder body.
  6.  
  7. Compress the pistons and install and tighten the front piston retainer screw.
  8.  
  9. Hold the washer in position and install the snapring.
  10.  
  11. Install the residual pressure valve and spring in the outlet port and firmly install the tube seats.
  12.  
  13. Bleed the master cylinder before installation.
  14.  

 
label.common.footer.alt.autozoneLogo