GM Full-Size Trucks 1988-1998 Repair Information

Height Sensing Proportioning Valve

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This valve distributes braking pressure evenly from front-to-rear depending on either a light or heavy load condition. Not all models utilize this valve.


CAUTION
Adjustment of the valve is determined by the distance between the axle and frame. The addition of such aftermarket items as air shocks, lift kits and addition spring leaves will render the valve inoperable, resulting in unsatisfactory brake performance, accident and injury!

REMOVAL & INSTALLATION



See Figures 1 and 2

Special gauging tools are required for this job.

  1. Raise and support the rear end on jackstands under the frame, allowing the axle to hang freely.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Height sensing proportioning valve-R/V Series



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Fig. Fig. 2: Height sensing proportioning valve-C/K Series

  1. Clean the exterior of the valve.
  2.  
  3. Disconnect the brake lines at the valve. Cap the lines.
  4.  
  5. Remove the valve shaft-to-lever nut.
  6.  
  7. Remove the valve-to-bracket bolts.
  8.  

To install:
  1. Position the valve on the bracket and tighten the bolts to 20 ft. lbs. (27 Nm).
  2.  
  3. Adjust the valve as described below.
  4.  
  5. Connect the lever to the valve shaft and tighten the nut to 89 inch lbs. (7 Nm).
  6.  
  7. Connect the brake lines and tighten them to 18 ft. lbs. (24 Nm).
  8.  
  9. Bleed the brakes.
  10.  

ADJUSTMENT



See Figures 3, 4 and 5

If front wheels lock-up at moderate brake pressure is experienced with the vehicle at or near maximum GVWR, or, whenever the valve is replaced, the valve must be adjusted.

Special gauging tools are required for this job.

  1. Raise and support the rear end on jackstands under the frame, allowing the axle to hang freely.
  2.  



Click image to see an enlarged view

Fig. Fig. 3: Installing the valve



Click image to see an enlarged view

Fig. Fig. 4: Installing the adjustment gauge



Click image to see an enlarged view

Fig. Fig. 5: After installation, sever the adjustment tang

  1. Remove the shaft-to-lever nut and disconnect the lever from the shaft.
  2.  
  3. Obtain the proper gauge:

    R and V with Extra Capacity Rear Spring option: part number 14061394; color green; code A
     
    R Series without Extra Capacity Rear Spring option, and with either the 6-4.3L or 8-5.7L engine: part number 14061395; color black; code B.
     
    V Series without Extra Capacity Rear Spring option and with the diesel engine or the 8-5.7L engine: part number 14061396; color blue; code C.
     
    R and V Series with VD1 tire option: part number 15592484; color red; code D.
     
    V Series, except above: part number 15548904; color yellow; code E.
     
    C/K Series: part number 15592484.
     

  4.  
  5. Rotate the valve shaft to permit installation of the gauge. The center hole of the gauge must seat on the D-shape of the valve shaft. The gauge tang must seat in the valve mounting hole.
  6.  
  7. Install the lever on the shaft with a C-clamp to seat the nylon bushings on the serrated valve shaft. Don't force it into position.
  8.  
  9. Install the nut on the shaft and tighten it to 89 inch lbs. (7 Nm) on the R/V series; 8 ft. lbs. (9 Nm) on the C/K Series
  10.  
  11. Break off or cut the tang on the gauge.
  12.  
  13. Road test the truck. The gauge will stay in place.
  14.  

 
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