Load-Sensing Proportioning & By-Pass Valve (LSP/BV Test

For testing purposes, rear axle is loaded to a specified weight. This specified weight may be added to vehicle and may or may not include rear vehicle weight.
See LSP & BV REAR AXLE TEST WEIGHT . On Pickup Cab and Chassis (C & C) models, if unladen weight exceeds LSP & BV REAR AXLE TEST WEIGHT table, go to step 5).
Attach Pressure Gauge Set (09709-29017) to front caliper and rear wheel cylinder or caliper. Bleed system. Depress brake pedal until front pressure reading reaches 1138 psi (80 kg/cm² ).
On Pickup C & C models, if unladen weight exceeds LSP & BV REAR AXLE TEST WEIGHT table, depress brake pedal until front pressure reaches 1422 psi (100 kg/cm² ).
On all models, wait 2 seconds and record pressure reading from gauge connected to rear wheel cylinder or caliper. Compare recorded pressure with specified brake pressure. See REAR BRAKE PRESSURES . Adjust fluid pressure by changing length of No. 2 shackle (if necessary). See Fig 1.

If rear pressure readings are low, distance "A" must be increased. For high pressure readings, distance "A" must be decreased. Turn No. 2 shackle one complete turn (360 degrees) for pressure change of 8.5 psi (.6 kg/cm² ).

LSP & BV REAR AXLE TEST WEIGHT

Application

Lbs. (Kg.)

2WD

1/2 Ton

1764 (800)

1 Ton & C & C ⁽¹⁾ (SRW)

1984 (900)

C & C ⁽²⁾ (DRW)

2535 (1150)

4WD

1984 (900)

⁽¹⁾	Add this amount to rear of vehicle.

⁽²⁾	On Pickup C & C models, if unladen weight exceeds specification, set rear axle load to 3699 lbs. (1678 kg.) with SRW and 4400 lbs. (1996 kg.) with DRW.

NOTE: DO NOT depress brake pedal more than once or release pedal while setting pressure on front gauge.

REAR BRAKE PRESSURES

Application

Rear Gauge psi (kg/cm² )

Pickup ⁽¹⁾

2WD

C & C ⁽²⁾ (DRW)

612-754 (43-53)

1/2 Ton

555-697 (39-49)

1 Ton, C & C (SRW)

569-711 (40-50)

4WD

Regular Cab

498-640 (35-45)

Extra Cab

555-697 (39-49)

4Runner ⁽¹⁾

615-757 (43.2-53.2)

⁽¹⁾	Rear brake pressure given is with front brake pressure set at 1138 psi (80 kg/cm² ).

⁽²⁾	Rear brake pressure given is with front brake pressure set at 1422 psi (100 kg/cm² ).

Repeat pressure tests after adjusting shackle length. If rear pressures fail specification after adjustment, reposition valve body. Raise valve body if rear pressures are too high, lower valve body if rear pressures are too low.
Ensure No. 2 shackle length is within adjustment range. If shackle is removed or replaced, adjust No. 2 shackle to standard length. See NO. 2 SHACKLE STANDARD LENGTH table. Adjusting range for Pickup 2WD is 2.83-3.31" (72-84 mm) and Pickup and 4Runner 4WD is 4.49-4.96" (114-126 mm). Adjusting range for all other models is 2.83-3.31" (72-84 mm).
If pressures cannot be adjusted, check valve housing. Position valve body in uppermost position. Apply brakes and record rear brake pressures. See VALVE BODY ADJUSTMENT for specified range. If measured value does not meet specification, replace valve assembly.
If correct pressure cannot be obtained by manipulating spring length, raise valve body to increase pressure or lower valve body to decrease pressure. If correct pressure still cannot be attained, replace valve body.

NO. 2 SHACKLE STANDARD LENGTH

Application		In. (mm)
Pickup
2WD		3.07 (78)
4WD		4.72 (120)
4Runner		3.07 (78)

VALVE BODY ADJUSTMENT

Application	Front Gauge psi (kg/cm² )	Rear Gauge psi (kg/cm² )
2WD (Single Wheels)
1st Reading	71 (5)	71 (5)
2nd Reading	356 (25)	128-185 (9-13)
3rd Reading	853 (60)	256-356 (18-25)
4WD (Dual Wheels)
1st Reading	71 (5)	71 (5)
2nd Reading	356 (25)	148-205 (10.4-14.4)
3rd Reading	853 (60)	311-411 (21.9-28.9)
4WD (Regular Cab)
1st Reading	142 (10)	142 (10)
2nd Reading	356 (25)	156-213 (11-15)
3rd Reading	853 (60)	235-334 (16.5-23.5)
4WD (Extra Cab)
1st Reading	1142 (10)	142 (10)
2nd Reading	356 (25)	168-225 (11.8-15.8)
3rd Reading	853 (60)	270-370 (19-26)

Fig 1: Measuring No. 2 Shackle Length & Spring Length

Fig 2: Exploded View of LSP & BP Valves

NOTE: Location and number of anti-rattle springs, anti-squeal shims, pad support and guide plates varies between models. Note component locations during removal process for reassembly reference.