How do you adjust the power brake master cylinder push rod?

Fabricate a gauge from #16 gauge sheet steel to the dimensions in Fig. 6 (1-3/4" wide, 2-7/8" tall, slot 0.980-0.995"). Place the gauge against the master cylinder mounting surface of the booster body and adjust the push rod screw so its end just touches the inner edge of the slot. Do not put side forces on the push rod. The push rod should not move more than 0.015 inch as it contacts the master cylinder piston; no movement (exact contact) is ideal.

What brake fluid does the manual specify for bleeding?

Rotunda Fluid—Extra Heavy Duty, Part Number C6AZ-19542-A. It is colored blue for identification. Do not mix low temperature brake fluids with it, and never re-use brake fluid drained from the hydraulic system.

How is the brake system manually bled?

The front and rear systems are bled separately, longest line first, keeping the reservoir from running dry. Put a 3/8 inch box wrench on the bleeder fitting, attach a rubber drain tube fitting snugly, submerge the tube end in clean brake fluid, loosen the fitting about 3/4 turn, slowly push the pedal through full travel, close the fitting, release the pedal, and repeat until air bubbles stop. Then close the fitting, remove the tube, and repeat at the opposite wheel cylinder, refilling the reservoir after each cylinder.

Can the secondary piston stop screw be used to bleed the brakes?

No. Do not use the secondary piston stop screw on the bottom of the master cylinder to bleed the brake system—loosening or removing it could damage the secondary piston or the stop screw.

What booster types are shown for push rod adjustment?

Fig. 7 shows push rod adjustment on a Midland-Ross unit and Fig. 8 shows it on a Bendix unit.

Home/ Registry/ Shelby/ GT500/ 1968 Shelby GT500/ Photo supermotors.net/registry/media/624301

Ford Shop Manual Brakes: Power Booster Push Rod Adjustment & Brake Bleeding

Group 2 Brakes manual page power brake master cylinder push rod adjustment and bleeding

‹ ›

Brake service manual page (Group 2) covering power brake master cylinder push rod adjustment with a #16 gauge sheet steel 0.980-0.995 gauge, and manual hydraulic bleeding procedure.

AI caption April 2008 · Photo 210 of 1457

This is page 2-4 from a Ford factory service manual, Group 2—Brakes. It covers three procedures: completion of a rear wheel adjustment (using torque wrench and Tool T66L-4204-L, checking for drag, torquing wheel nuts to specification); power brake master cylinder push rod adjustment; and manual bleeding of the hydraulic brake system. For push rod adjustment, the reader fabricates a gauge from #16 gauge sheet steel to the dimensions in Fig. 6 (1-3/4", 2-7/8", 0.980-0.995", 3/4", 1-1/16") and adjusts the screw so it just touches the gauge slot; the push rod should not move more than 0.015 inch when contacting the master cylinder piston. Figures 7 and 8 illustrate the adjustment on Midland-Ross and Bendix boosters respectively. The bleeding section specifies keeping reservoirs filled with Rotunda Extra Heavy Duty fluid, Part Number C6AZ-19542-A (colored blue for identification), warns never to re-use drained fluid or mix low-temperature fluids, and gives a step-by-step manual bleeding procedure using a 3/8 inch box wrench (Fig. 9) on the bleeder fitting, a submerged rubber drain tube, and slow full-travel pedal strokes until air bubbles stop. It also warns not to use the secondary piston stop screw on the bottom of the master cylinder for bleeding.

Is this accurate? Sign in to help verify it.

Frequently asked questions

How do you adjust the power brake master cylinder push rod?: Fabricate a gauge from #16 gauge sheet steel to the dimensions in Fig. 6 (1-3/4" wide, 2-7/8" tall, slot 0.980-0.995"). Place the gauge against the master cylinder mounting surface of the booster body and adjust the push rod screw so its end just touches the inner edge of the slot. Do not put side forces on the push rod. The push rod should not move more than 0.015 inch as it contacts the master cylinder piston; no movement (exact contact) is ideal.
What brake fluid does the manual specify for bleeding?: Rotunda Fluid—Extra Heavy Duty, Part Number C6AZ-19542-A. It is colored blue for identification. Do not mix low temperature brake fluids with it, and never re-use brake fluid drained from the hydraulic system.
How is the brake system manually bled?: The front and rear systems are bled separately, longest line first, keeping the reservoir from running dry. Put a 3/8 inch box wrench on the bleeder fitting, attach a rubber drain tube fitting snugly, submerge the tube end in clean brake fluid, loosen the fitting about 3/4 turn, slowly push the pedal through full travel, close the fitting, release the pedal, and repeat until air bubbles stop. Then close the fitting, remove the tube, and repeat at the opposite wheel cylinder, refilling the reservoir after each cylinder.
Can the secondary piston stop screw be used to bleed the brakes?: No. Do not use the secondary piston stop screw on the bottom of the master cylinder to bleed the brake system—loosening or removing it could damage the secondary piston or the stop screw.
What booster types are shown for push rod adjustment?: Fig. 7 shows push rod adjustment on a Midland-Ross unit and Fig. 8 shows it on a Bendix unit.