Similar to most other repairs and procedures, the proper vehicle alignment begins with good communication. “The interview process with the customer is critical,” said Mitch Weller, heavy-duty product manager, Hunter Engineering Company.
“There may be a language barrier between the customer’s explanation of the problem and the experienced technician’s or service writer’s terminology describing the problem. Many times the customer will complain about something that may not be the issue.
“For example, he may say that he needs an alignment, when in reality, he’s having a vibration problem,” he said. “The best thing to do is to take the vehicle for a road test with the customer; that way you can identify what the problem actually is.”
Once you’ve verified what the problem may be, it’s important that you adhere to the proper inspection and repair procedures.
According to the Technology & Maintenance Council (TMC), you must perform the following procedures at each preventive maintenance interval.
- Inspect all tire/wheel assemblies for tire wear conditions, and record all observations.
- Check cold inflation pressure of all the tire/wheel assemblies with a calibrated gauge and correct any problems. Record findings before and after readings by wheel position.
- Verify wheel attachment as well as the fastener torque.
- Take the vehicle for a road test drive, and record all discrepancies and observations.
- Perform other suspension and steering maintenance as recommended in the appropriate vehicle manufacturer’s service manual.
- Perform an all-axle alignment on the vehicle. Record all the adjustment readings before and after the alignment, and then compare the readings taken before the adjustment to the observed wear conditions and test ride results.
- If there is any evidence of uneven or irregular tire wear, rotate the tires so that they are rolling in the opposite direction from their original position.
TMC has detailed guidelines on how to perform a proper all-axle alignment.
- Check cold tire inflation pressure.
- Road test the vehicle.
A preliminary test drive is needed to determine the vehicle’s handling dynamics. Primarily, the straight ahead stability of the truck must be tested thoroughly. You can ask if the steering pull to the right, left or wander in alternate directions.
A consistent drift or pull to one side creates a counter-steer dynamic. Aiming the steering tire at an angle to the direction of travel causes tire wear. The wear pattern will appear as scuff, outside-in on one steer tire and inside-out on the opposite tire.
This type of wear magnifies any other existing tire wear conditions on the steering axle. During the preliminary test drive, any other handling complaints can be addressed. The post-test must be performed if any action has taken place during the inspection, for example, tire pressure changes, tire replacement, tire rotation, component replacement or repair of the steering or suspension system, alignment adjustment or any chassis alteration that may affect handling, according to TMC.
The pre-test or complaint may be severe enough to warrant a loaded test. The pull test should be repeated, and the vehicle should be sent to a qualified alignment facility if the problem persists.
- You must be sure to check all steering, suspension and frame components and all axles.
- Tie rod and ends-Check for damage, tightness, wear and adequate lube.
- Steering Arms-Check for damage, wear and connecting nut torque.
- Draglink-Check for damage, play, wear and adequate lube if applicable.
- Pitman Arm-Check for connecting nut torque and timing position.
- Steering Sector-Check for play outside of the manufacturer’s specs at the steering wheel and feel for gear play. Adjust the bearing preload if applicable, and check the steering gear for box-to-frame mounting bolt torque.
- Steering Shaft-Make sure the steering driveline, the U-joint and portions of the steering linkage are lubed adequately. Check for damage and wear in moving parts, and check for driveline timing mark alignment.
- Steering Knuckle-Check for worn or damaged kingpin seals, bushings and bearings. Lube as needed to prevent wear or hard setting.
- Maximum Steer Angle-Inspect the steering stops for damage. Steering turn angle is the degree of front wheel movement from a straight-ahead position to either an extreme right or left position.
Although front wheel movement can be limited by the amount of internal travel in the steering gear, it generally depends on how much clearance there is between chassis components and the tire and wheel assemblies. Most steer axles have an adjustable stop screw and locknut-type axle stops located on the rear side of each front axle spindle.
- U-bolts-Inspect the u-bolts for any evidence of movement requiring re-torquing.
- Shock absorbers-Inspect shocks for any signs of leakage, damage or bushing wear.
- Check brake drum centering.
- Check wheel bearing end play.
- Check wheel/tire runout, both lateral and radial.
- Check tire mounting.
- Inspect the tires for any signs of irregular, unusual or fast wear.
- Check the vehicle’s ride-height, and adjust to the manufacturer’s specifications.
- Check the vehicle’s steer axle spindle height.
- Position the vehicle in the alignment area by driving straight ahead with very minimal use of the brake and the throttle.
- Measure and record the alignment parameters.
- Road test the vehicle.
It’s important that you “make sure all tire conditions and pressures are correct, that the correct tires are being used for the particular application and that the tires are not worn badly,” Hunter’s Weller explained.
Tire wear is the strongest indicator of an alignment condition, so pay careful attention to them. If tires wear too quickly, you may need to inspect the vehicle’s alignment and make corrections as needed.
Mike McCoy, sales manager, Bee Line Company, said that the technician should check the vehicle’s alignment every time he puts on a new set of steer axle tires. “That way he can look at the tires as he takes them off the vehicle to observe any wear patterns that may point to a misaligned vehicle,” he said.
Some common tire wear patterns can help isolate specific alignment problems. The most common types of wear include overall fast wear, feather wear, cupping, diagonal wear, rapid shoulder wear and one-sided wear, according to TMC.
Vehicles become misaligned for a number of reasons, including rough roads, pot holes, worn parts, overloading and the number of miles driven. “Normally, alignment doesn’t change; something happens that causes it to change,” McCoy said.
According to TMC, a vehicle’s alignment should be checked every 15,000 to 30,000 miles, but no later than 90 days after the vehicle goes into service for the first time. Subsequent alignments should take place at 80,000 to 100,000 mile intervals or at 12 to 18 month intervals, whichever comes first. You also should check the vehicle’s alignment anytime a component that affects alignment is replaced.
“Application has a great deal to do with alignment intervals, however, a cautious driver can help this,” Weller said. “Delivery trucks turn frequently and have far more incidences of hitting curbs or obstacles that can affect alignment negatively, whereas over-the-road trucks need less frequent alignments.”
McCoy said that drivers should make sure to follow proper suspension maintenance practices such as greasing intervals, for example, and try to avoid harsh road conditions that may put the vehicle’s alignment at risk.
Tell you customer that he should avoid driving over or backing over curbs, and when given a choice, he should try to travel on smoother roads, Weller said. “He should keep tire pressures at the specified level, follow recommended maintenance intervals for lubrication of the suspension components and follow the recommended loading standards for his particular vehicle.
“Once the appropriate parts are replaced as needed, or if the vehicle is determined to be in good condition, you must align the vehicle on professional equipment with pre-align and after-alignment printout capability,” Weller said.
McCoy added, “Good equipment that is properly calibrated is necessary, and the technicians must be trained to perform proper alignment procedures and on how to use the equipment.”
Weller said that the quality of technicians and the available training are big issues the industry faces, especially when it comes to proper vehicle alignment. “We need to raise the bar on the quality of technicians and what we invest in them. Proper training is critical to understanding such things as tire wear issues and how to test components correctly,” he said.
“Many components are deemed bad when in fact they aren’t, and too often vehicles are aligned without having their suspension components inspected. That means the vehicle may be aligned, but with worn components, then the owner assumes the alignment was done improperly, loses faith in the process and may not have preventive alignments performed in the future,” Weller said.
There are several different ways of approaching alignment, some of which have been used for 50 years, he added. “A lot of companies have not changed their equipment with the times, and too many things still are done mechanically, with tape measures for example.”
Suspensions are getting more complex and sophisticated, “so the quality of technicians will have to improve to maintain the trucks of tomorrow,” Weller said.
“Technology is advancing, and it’s critical for complete accuracy; it exists to help the operator make fewer mistakes,” he said. “Good technology makes good technicians better.”
McCoy said, “Newer computerized systems that use lasers and PCs, for example, aid the technician. The computer alignment gauging systems show the technician step-by-step alignment procedures, then tells him what adjustments to make and how to do so.
“The system prompts him to perform certain readings and then tells him what to do with those readings,” he said. “The equipment also stores readings for future reference.”
Because alignment equipment is so technical, it must be maintained to ensure accurate readings. Weller said, “Buying an alignment system is a big investment. A purchaser should consider service availability when deciding if, when and how to purchase an alignment system.”
He added that studies by a number of sources show that 70% to 80% of trucks today are out of alignment. Alignment condition inspection equipment is available to catch problems before they result in tire wear, component wear and fuel usage increases. “Regular testing can result in annual savings of thousands of dollars,” he said. “A little preventive testing can go a long way.”
McCoy added, “Alignment should be thought of as preventive maintenance, like an oil change. If you do it routinely and check to make sure everything is in order, you’ll save your customers time and money.”
According to the Technology & Maintenance Council, the following are terms that may be useful in explaining various aspects of total vehicle alignment.
Ackerman Steering Geometry: The geometry of the four-bar linkage consisting of the front axle beam pivot points, tie rod arms and cross tube and attempts to provide free rolling of the front tires in a turn.
Ackerman geometry is dependent upon the steering axle track width and wheelbase of the vehicle. Improper geometry results in wheel scrub in turns, which generally appears as toe wear on the tire, usually more wear on one side of the vehicle than the other side because of the operational route of the vehicle.
Bump Steer (Feedback): This is the feedback felt through the steering linkage to the steering wheel when a steer axle tire hits a bump in the road. This occurs because the axle end of the drag link and the axle attachment point of the spring do no travel in parallel circular arcs as the suspension moves up and down. This condition also can be caused by trapped air in the power steering system.
King Pin Inclination: This is the inward tilt of the king pin from the vertical. This front suspension parameter has a pronounced effect on steering effort and returnability. As the front wheels are turned around an inclined king pin, the front of the truck is lifted. The lifting of the vehicle is experienced as steering effort when the turn is executed and exhibits itself as a recovery force when the steering wheel finally is released.
King Pin Offest: It is the distance between the center of the tire patch and intersection of the king pin axis with the ground. This parameter of front end geometry is important in vehicles without power steering and has a major effect on static steering.
If there is no king pin offset, the tires must scrub around the center of the pin patch when turned in a static condition, resulting in higher static steering efforts.
Steering Arm: This component is one that connects the draglink to the axle knuckle assembly.
Tie Rod Arm: This component is supposed to transmit steering forces between the left and right axle knuckle assemblies through the cross tube assembly.
Toe-Out On Turns: Excessive turning angles such as those encountered in pickup-and-delivery operations may contribute to premature tire wear. Be advised that the greater the turning angles, the more that toe and camber change. If you have any doubt about the optimum turning angles for your operation, contact the vehicle, tire and alignment equipment manufacturers.
According to the Technology & Maintenance Council (TMC), total toe is the angle formed by two horizontal lines through the planes of two wheels. Toe-in is when the horizontal lines intersect in front of the wheels, or the wheels are closer together in front than in back.
Toe-out is when the horizontal lines intersect behind the wheels, or the wheels are closer together in back than in front. Toe-in commonly is referred to as positive, and toe-out as negative, TMC explained.
Steer axle toe is adjustable to reduce wear to the leading edge of the tire and also to avoid road wander. Excessive toe-in wears the outside edge of the tires. Excessive toe-out wears the inside edge of the tires. Toe is adjusted in a static, unloaded condition so that the tires will run in a straight line under a dynamic, loaded condition, according to TMC.
Who To Contact
For more information on vehicle alignment procedures, you may contact the following companies directly. Other companies offering information on alignment can be found in the Truck Parts & Service Aftermarket Buyers’ Guide & Directory as well as in Buyers’ Guide section on our web site at www.truckpartsandservice.com.
Bee Line Co.
Hunter Engineering Company
Josam Products, Inc.
MD Alignment Services, Inc.