Issue link: http://read.dmtmag.com/i/34501
ALIGNMENT - FIELD METHOD ATTACC PLUS SYSTEM (Axle, Thrust, Toe, Ackerman, Camber, Caster Parts, Labor, User Saves) • Simple vehicle measurement system • Quick, low cost, yet effective method • Determine if poor alignment conditions exist • Minimum tools required Refer to MICHELIN Video, ATTACC Plus (MWV41200) for reference. SET-UP INSTRUCTION PROCEDURES TOOLS: • Chalk Line (no chalk) • 2 Cans of White Spray Paint • Metric Tape Measure • 1 pair of Jack Stands • 2 Large Heavy Duty Plastic Bags • Toe-Scribe • Vehicle Jack (10 Tons) • Flashlight • Line Level and Wheel Chocks • 1 T-45A Tire Iron SURFACE: Inspection site should be fairly level; use Line Level if necessary to determine slope. STEER/DRIVE TIRES: Note tread design, DOT, tread depth, psi, tire conditions and mileage, and all normal pertinent vehicle information. VEHICLE POSITIONING 1. Drive vehicle straight into inspection site, at least 3 full vehicle lengths, to ensure it’s straight into site. Driving into and backing out of the work area several times will ensure the vehicle's suspension components are relaxed to achieve proper measurements. 2. Allow vehicle to roll to a stop, shut-off the engine, and let up on the clutch. 3. Let vehicle fully stop by transmission, no brakes. 4. Engage tractor parking brakes and take out of gear; place wheel chocks on the drive tires. MEASUREMENTS Record all measurements. Front of Vehicle 1.Measure steering axle skew from the front of the outside U-bolt to the zerk fitting (or bolt) on the front spring pin perch. Tolerance is ± 3⁄16" or 5 mm side to side. 2.Measure for straight ahead steering from the inner wheel flange to edge of the leaf spring (if newer style tapered frame) or frame on both sides of the vehicle to ensure the steer tires are straight ahead (tolerance is 1⁄32" or 1 mm side to side). Adjust the steering wheels as necessary to come within tolerance. Mark the steering wheel column with a crayon for future reference. 3. Measure for steering axle offset from the frame rail to the vertical center line on the tire on both sides. Tolerance is ± 3⁄16" or 5 mm from centerline of vehicle. 4. Steering Stops: Ensure they are in place on left and right sides, and measure length. Stops control the angle 118 Section Nine: Appendix of the turn and may be a consideration if abnormal steer tire wear is present. 5. Check front end components and toe by jacking up front end after placing wheel chocks on the rear tires. Place the floor jack under the axle for support, use the T-45A tire iron by inserting into the wheel assembly at the 6 o’clock position and place your other hand at the 12 o’clock position. With a rocking type motion try to move the tire assembly up with the lower bar and out towards you with your left hand. If play is felt, it is probably the result of loose wheel bearings or worn kingpin bushings. If you observe the brake chamber moving, it can be isolated to the kingpin bushing. If it does not move, it is likely the wheel bearings. With your hands placed at the 3 o’clock and at the 9 o’clock positions on the tire, try to move the tire in a rapid “left turn – right turn” type of motion. Feel and listen for any play. Play in this area would indicate either loose or worn tie rod ends, steering arms, drag link ends, or steering box play. Any play in this area should be further inspected to ensure it is within the vehicle and/or part manufacturer’s specifications. Two additional parts that can cause tire wear need to be checked. First, see if the brake drum has a balance weight and second, look for wear on the spring shackle assembly. This check is more difficult to make, and there are various ways to inspect for this wear. Consult the part manufacture for the proper way to inspect. On a dry tire, with a can of spray paint, marker, or chalk (dusting with any coating material suitable for marking a section of tread), “highlight” a section of the tread area around the tire. With a sharp pointed scribe, mark a thin line in the highlighted area while rotating the tire. (Note: At this point observe the amount of radial and lateral runout by referencing this line to the rotating tire. Any runout greater than 3⁄32nd inch should be further investigated for improper tire bead seating, improper tire/wheel runout and/or improper wheel torque procedure during installation.) Repeat this process on the other steer tire. Check for steer ahead by referencing the mark on the steering wheel column (or measure as in Paragraph 2 above), and lower the vehicle on the folded plastic bags. Plastic should be folded to just larger than the tire footprint so that no part of the steer tires will make contact with the ground. Prior to measuring, you should “joust” the vehicle by standing on the step and shaking the unit with your body weight. This will further relax the front suspension, giving you a correct toe reading. Once the steer tires are down, measure from side to side between the scribed lines, first rear, then front, with a tape measure or a fine lined toe gauge to determine relative toe. Do this with the paint cans on the ground, centered