Brake Proportioning/Combination Valve: Service and Repair

Fig 35 Type 3 Proportioning Valve Identification:

Rear Wheel Proportioning Valve Location On HCU:

GENERAL INFORMATION
The HCU does not require removal from the vehicle for the replacement of the proportioning valves. Use the proportioning valve test procedure under Testing and Inspection to determine which proportioning valve requires replacement, then replace it using procedure below.

REMOVE
1. Disconnect the brake tube fitting from the proportioning valve requiring removal from the HCU.
2. Remove proportioning valve requiring replacement, from the HCU.

INSTALL
1. Wet O-ring seal on new proportioning valve using clean fresh brake fluid.
2. Install proportioning valve in HCU and hand tighten until proportioning is fully installed and 0-ring seal is seated into HCU. Then torque proportioning valve to 40 Nm (30 ft. lbs.).
3. Install brake tube on proportioning valve. Tighten tube nut to 17 Nm (145 inch lbs.) torque.
4. Bleed the base brakes hydraulic system. Refer to Brakes Service and Repair.