1942 - 1947 Chevrolet Shop Manual



	*5-15*

	Valve adjustments are made in the following manner: 1. Remove the clevis pin which fastens the piston rod and valve links to the power and valve operating levers. Push the piston rod away from the operating and valve levers.	If the piston moves toward the applied position but will not release, the valve is positioned too far out in the piston rod. To correct the adjustment, remove the piston rod yoke clevis pin and special bushing and loosen the valve links lock-nut. Hold the valve rod with a pair of pliers and turn the valve links 1/2 turn to the left or counterclockwise. Fig. 36. Reassemble the clevis pin and bushing and repeat the test. If the 1/2 turn of the valve links does not correct the condition, repeat the adjustment 1/2 turn at a time until the piston will move in both directions as outlined in 3 and 4. If the piston moves toward the released position but will not move in the applied direction, the valve is adjusted too far into the piston rod. In this case the valve links must be turned 1/2 turn to the right or clockwise until the proper adjustment is obtained. Best performance is secured by turning the valve links 1/2 turn to the right or clockwise,


	Fig. 34—Installing Adjusting Bushing 2. Start the engine. Place the special adjusting bushing in position through the over-diameter bushing in the valve links. Insert the clevis pin through the piston rod yoke and adjusting bushing, Fig. 34. 3. Move the valve links away from the cylinder until the special adjusting bushing bottoms against the piston rod yoke clevis pin, having all clearance away from the cylinder, Fig. 35. In this position the piston rod should move slowly away from the cylinder, or in the applied position.
		Fig. 36—Adjusting Vacuum Valve after correct adjustment has been obtained. This places the valve in a position slightly favoring the application stroke. Leverage Adjustment 1. Remove the clevis pin which fastens the brake pedal rod to the valve operating lever.


	Fig. 35—Checking Vacuum Valve Adjustment 4. Now move the valve links towards the cylinder with all clearance between the adjusting bushing and piston rod yoke clevis pin towards the cylinder. In this position the piston rod should move towards the cylinder, or to the released position.
		Fig. 37-Adjusting Brake Pedal Pull Rod 2. Remove the clevis pin from the hydraulic main cylinder piston rod yoke and power lever.