Dodge Omni/Horizon/Rampage 1978-1989 Repair Guide

Master Cylinder

Print



Click image to see an enlarged view

Fig. Fig. 1 Master cylinder exploded view

REMOVAL & INSTALLATION



With Power Brakes
  1. Disconnect the primary and secondary brake lines from the master cylinder. Plug the openings.
  2.  
  3. Remove the nuts attaching the cylinder to the power brake booster.
  4.  
  5. Slide the master cylinder straight out, away from the booster.
  6.  

To install:

  1. Position the master cylinder over the studs on the booster, align the pushrod with the master cylinder piston and tighten the nuts to 16 ft. lbs. (22 Nm).
  2.  



Click image to see an enlarged view

Fig. Fig. 2 On vehicles equipped with power brakes, the master cylinder is mounted to the booster

  1. Connect the brake lines.
  2.  
  3. Bleed the brakes.
  4.  

Without Power Brakes
  1. Disconnect the primary and secondary brake lines and install plugs in the master cylinder openings.
  2.  



Click image to see an enlarged view

Fig. Fig. 3 Whenever possible, use a flare wrench to disconnect the master cylinder brake lines

  1. Disconnect the stoplight switch mounting bracket from under the instrument panel.
  2.  
  3. Pull the brake pedal backward to disengage the pushrod from the master cylinder piston.
  4.  


WARNING
This will destroy the grommet. Use a new one when installing the master cylinder.

  1. Remove the master cylinder-to-firewall nuts.
  2.  



Click image to see an enlarged view

Fig. Fig. 4 Remove the master cylinder-to-firewall nuts

  1. Slide the master cylinder out and away from the firewall. Be sure to remove all pieces of the broken grommet.
  2.  

To install:

  1. Install the boot on the pushrod.
  2.  
  3. Install a new grommet on the pushrod.
  4.  
  5. Apply a soap and water solution to the grommet and slide it firmly into position in the primary piston socket. Move the pushrod from side to side to make sure it's seated.
  6.  
  7. From the engine side, press the pushrod through the master cylinder mounting plate and align the mounting studs with the holes in the cylinder.
  8.  
  9. Install the nuts and tighten them to 16 ft. lbs. (22 Nm).
  10.  
  11. From under the instrument panel, place the pushrod on the pin on the pedal and install a new retaining clip.
  12.  


WARNING
Be sure to lubricate the pin.

  1. Install the brake lines on the master cylinder.
  2.  
  3. Bleed the system.
  4.  

OVERHAUL




CAUTION
Do not hone the master cylinder bore. Honing will remove the anodized finish.

  1. Clean the housing and reservoir.
  2.  
  3. Remove the reservoir caps and empty the fluid.
  4.  
  5. Clamp the master cylinder in a soft-jawed vise.
  6.  
  7. Pull the reservoir from the master cylinder housing.
  8.  



Click image to see an enlarged view

Fig. Fig. 5 Carefully mount the master cylinder in a vise, then pull the reservoir from the cylinder housing

  1. Remove the reservoir grommets.
  2.  



Click image to see an enlarged view

Fig. Fig. 6 Remove the reservoir grommets

  1. Use needle-nosed pliers to remove the secondary piston pin from inside the housing.
  2.  



Click image to see an enlarged view

Fig. Fig. 7 Use needle-nosed pliers to remove the secondary piston pin from inside the housing

  1. Remove the snapring from the outer end of the housing.
  2.  
  3. Slide the primary piston out of the master cylinder bore.
  4.  



Click image to see an enlarged view

Fig. Fig. 8 After removing the snapring from the housing, slide the primary piston out of the master cylinder bore

  1. Tap the open end of the cylinder on the bench to remove the secondary piston. If it sticks in the bore, it can be removed with light air pressure.
  2.  


WARNING
If air pressure is used to remove the piston, new cups must be installed.

  1. Note the position of the rubber cups and remove all except the primary cup.
  2.  



Click image to see an enlarged view

Fig. Fig. 9 Remove the rubber cups excluding the primary cup


WARNING
Do not remove the primary cup from the primary piston. If the cup is worn, the entire primary piston assembly should be replaced.

  1. If the brass tube seats are not reusable, replace them using a suitable tool.
  2.  
  3. Wash the entire housing in clean brake fluid and inspect for pitting or scratches. If any are found, replace the housing. If the pistons are corroded, they should be replaced. Discard all used rubber parts and replace piston caps and seals.
  4.  
  5. Before assembly, dip all parts in clean brake fluid.
  6.  



Click image to see an enlarged view

Fig. Fig. 10 Before assembly, dip all parts in clean brake fluid. Make sure you have all the parts!

  1. Install the check flow washer.
  2.  
  3. Install the secondary piston into the master cylinder bore. Be sure the cup lips enter the bore evenly. Keep well lubricated with brake fluid.
  4.  
  5. Center the primary piston spring retainer on the secondary piston and push the piston assemblies into the bore up to the primary piston cup.
  6.  
  7. Work the cup into the bore and push the piston in up to the secondary seal. Work the cup into the bore and push on the piston until fully seated.
  8.  
  9. Depress the piston and install the snapring.
  10.  
  11. Tap the secondary piston retainer pin into the housing.
  12.  
  13. Install new tube seats.
  14.  
  15. Install the reservoir grommets in the housing. Lubricate the area with clean brake fluid and install the reservoir. All the lettering should be properly read from the left side of the reservoir when it is properly installed. Make sure the bottom of the reservoir touches the top of the grommet.
  16.  

 
label.common.footer.alt.autozoneLogo