Suspension Height Checking

em2 mm 32.01.004

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:

  • 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 (500 N·cm). Any damage to the valve housing will void the warranty.

  • 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.

Notice: When removing or loosening a Barksdale height-control valve from a mounting bracket, always hold the valve-side mounting studs in place with an Allen wrench while loosening or tightening the nuts that attach the valve to the bracket. Because the mounting studs are threaded into the valve body, loosening the nuts without holding the studs can tighten the studs, which can crush the valve body and damage the valve. Conversely, tightening the nuts without holding the studs can back the studs out, causing a separation of the two halves of the valve body, and possibly a leak.
  1. 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.
  2. Mark the location of the front and rear tires on the floor.

    3. Note: The stud bolt that fastens the valve's height-control lever to the vertical linkage is oriented correctly when the linkage rod is vertical, as viewed from the side of the vehicle; see Fig.. The rod may be on the forward or aft side of the lever to get it to be vertical.

  3. Measure the distance between the left forwardmost axle stop and the suspension as indicated; see Table. for an acceptable range of heights for each suspension.

    1. Valve Mounting Bracket

    2. Height-Control Valve

    3. Stud Bolt

    4. Linkage Rod

    5. Axle

    Fig. 1, Barksdale Height-Control Valve Installation (side view) (typical)

    4. Important: Suspensions with Single-Leaf Springs: Measure between the top of the U-bolt pad and the bottom of the axle stop.

  4. If the measurement is not within the acceptable range, refer to the eM2 Workshop Manual for adjustment instructions. If the distance is within the acceptable range, apply the parking brakes.

    Table 1, Suspension Ride-Height Measurement, Single-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, Single-Leaf Spring, 21k/40k, High Ride

    Note:
    Parent topic: Freightliner AirLiner Rear Suspension Check
    Document Number: 0000121547
    Manual Publication Date: 2025-02-11
    Topic Publication Date: 2024-06-04