Toyota Pick-ups, Land Cruiser, and 4 Runner 1997-00

Load Sensing Proportioning (LSP) and Bypass Valve (BV)

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The purpose of this valve is to control the fluid pressure applied to the brakes to prevent rear wheel lock-up during weight transfer at high-speed stops.

REMOVAL & INSTALLATION





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Fig. The load sensing valve can usually be found secured to the frame rail



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Fig. Exploded view of the load sensing valve and its related components



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Fig. Remove the shackle from the bracket



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Fig. Remove the LSP and BV assembly

  1. Disconnect the shackle from the bracket.
  2.  
  3. Remove the cotter pin, then the nut and cushion retainer.
  4.  
  5. Disconnect the shackle and remove the cushions and collar.
  6.  
  7. Disconnect the brake lines attached to the valve. Plug the lines to keep dirt from entering.
  8.  
  9. Remove the mounting bolt, if used, and remove the valve.
  10.  

To install:

This valve cannot be rebuilt. If it fails, the valve must be replaced.

  1. Install the LSP and BV assembly to the frame; tighten to 1922 ft. lbs. (2529 Nm).
  2.  
  3. Install the shackle to the load sensing spring.
  4.  
  5. Attach the shackle to the shackle bracket, tighten to 9 ft. lbs. (13 Nm).
  6.  
  7. Install a new cotter pin.
  8.  
  9. Attach the brake lines, tighten to 11 ft. lbs. (15 Nm).
  10.  
  11. Set the valve body as follows:
    1. When pulling the load sensing spring, confirm that the valve piston moves down slowly.
    2.  
    3. Position the valve body so that the valve piston lightly contacts the load sensing spring.
    4.  
    5. Tighten the valve body mounting nuts to 9 ft. lbs. (13 Nm).
    6.  

  12.  
  13. Bleed the brake system.
  14.  

ADJUSTMENT



This is an initial adjustment which should bring the valve close to specifications. Since it requires the use of pressure gauges and determines the exact weight of the load on the rear axle, it is not practical for the owner/mechanic. Have the final adjustments performed at a reputable shop as soon as possible.

  1. Pull down the load sensing spring to determine that the piston moves slowly.
  2.  
  3. Set the valve body so that the piston lightly touches the load sensing spring.
  4.  
  5. Tighten the mounting bolts.
  6.  
  7. Adjust the length of the shackle. Lengthening the distance between the centers lowers the pressure; shortening the distance raises the pressure. One full turn of the nut increases pressure about 20 psi. on Land Cruiser, or about 1114 psi (7596 kPa) on all other vehicles. Initial length of this link should be:

    4Runner and Tundra: 3.54 inches (90mm)
     
    Land Cruiser: 3.54 inches (90mm)
     
    T100: 4.72 inches (120mm)
     
    Tacoma 2WD: 3.07 inches (78mm)
     
    Tacoma 4WD: 4.72 inches (120mm)
     

  8.  
  9. If the initial distance is correct, fluid metering should be very close to specification.
  10.  



Click image to see an enlarged view

Fig. Measure the distance between the centers of the shackles

 
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