Suspension Height Checking
Important: Before checking the AirLiner suspension height, make sure there is no load on the chassis, and the trailer is unhitched.
Important: To prevent voiding the warranty on Barksdale height-control valves, note the following:
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Do not overtighten the bolts in the Barksdale height-control valve housing. The bolts should not be loose, and should not require tightening. Only if necessary, tighten the valve housing bolts 45 lbf·in (508 N·cm). Any damage to the valve housing will void the warranty.
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Do not attempt to disassemble the Barksdale valve body or the control lever. There are no serviceable parts in the valve, and any disassembly will void the warranty.
- Park the vehicle on a level surface, using a light application of the brakes. Do not apply the parking brakes. Shift the transmission into neutral, and build the secondary air pressure to at least 100 psi (690 kPa). Shut down the engine. Have an assistant chock the tires on one axle only.
- Mark the location of the front and rear tires on the floor.
- Measure the distance between the left forwardmost axle
stop and the suspension as indicated; see Table., Table., Table., Table. and Table. for an acceptable range of heights for each suspension.
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The screw tip must extend about 1/4 inch (6 mm).
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Belleville washers must collapse almost flat.
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Tightening Screw Hex
Fig. 1, Barksdale Height-Control Valve Installation (side view) (typical)
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- If the measurement is not within the acceptable range,
refer to the 57X Workshop Manual for adjustment instructions.
If the distance is within the acceptable range, apply the parking
brakes.
Table 1, Suspension Ride-Height Measurement, Dual-Leaf Spring, 21k/40k High Ride
Measure Point Suspension Height Measurement Min Target Max A = Measure Here
2-3/8 inch (60 mm)
2-5/8 inch (67 mm)
2-7/8 inch (73 mm)
Table 1, Suspension Ride-Height Measurement, Dual-Leaf Spring, 21k/40k High Ride
Table 2, Suspension Ride-Height Measurement, Single-Leaf Spring, 40k Low and Mid Ride
Measure Point Suspension Height Measurement Min Target Max A = Measure Here
2-3/8 inch (60 mm)
2-5/8 inch (67 mm)
2-7/8 inch (73 mm)
Table 2, Suspension Ride-Height Measurement, Single-Leaf Spring, 40k Low and Mid Ride
Table 3, Suspension Ride-Height Measurement, Single-Leaf Spring, 40k Low and Mid Ride
Measure Point Suspension Height Measurement Min Target Max A = Measure Here
2-3/8 inch (60 mm)
2-1/2 inch (64 mm)
2-7/8 inch (73 mm)
Table 3, Suspension Ride-Height Measurement, Single-Leaf Spring, 40k Low and Mid Ride
Important: For suspensions with dual-leaf springs, measure between the top of the U-bolt and the bottom of the axle stop. For suspensions with single-leaf springs , measure between the top of the U-bolt pad and the bottom of the axle stop.
