Interested in a sure-fire way for your shop customers to consistently turn out a measurably better product? Help them put more emphasis on steering repairs. There, wasn’t that easy? Granted, that may rank among the strangest statements you’ve heard about your business. Next to the economy, pay rates, cycle time and training employees, placing a renewed interest on steering system repairs just may not seem all that important to service dealers. Steering repairs aren’t the kind of high-dollar services capable of turning a business around or making the difference between a decent and a great sales month.
What’s the big deal then with steering? Why should they pay attention to it? Consider this. Steering is perhaps the single most vital system in an automobile. Along with the wheels, brakes and engine, steering has been a key part of the automobile since its inception. With each new generation of vehicles, steering technology has made the driving experience safer, easier and a lot more enjoyable. Indeed, in many ways, being able to maneuver in and out of tight parking spaces and through heavy traffic, along with zipping along curvy roadways, has become the heart of the driving experience.
Add to this the personal level of familiarity most drivers have with their vehicles’ handling and you get a sense of just how powerful the connection between driver and steering is.
Is it any wonder then that consumers might put so much emphasis on the way their vehicles handle when they gauge the quality of repair work? Keep in mind that they make judgments based on the way their vehicles handle every time they sit behind the wheel, even many weeks after their vehicles have been in for repairs. The bottom line is that how well and how thoroughly your customers handle steering repairs goes a long way in determining whether they will get repeat business. And whether those customers will send friends and family members to the same shops.
If that isn’t convincing, consider the following. Steering is tied in with airbag, seatbelt and other safety systems. Shops are liable for that work. Their shop, the livelihoods of their employees and their customers’ safety is dependent on correct repair decisions. How comfortable are your service dealer customers with their levels of understanding in these areas? Do they understand steering systems well enough to answer customer questions or to fully explain steering repairs? What about their employees?
Dealing with this critical system is a hefty responsibility, but doing it right —which means offering the most thorough, up-to-date service possible — can prove immensely rewarding. Doing it right starts with re-education of how this system functions and how it should be diagnosed and repaired. Read on.
Steering system basics
Modern steering systems come in two basic types: rack-and-pinion, featured on most cars, small SUVs and pickup trucks, and recirculating ball, found mostly on larger trucks and SUVs. Rack-and-pinion steering is used on most cars and small trucks because it’s lighter than recirculating ball steering, which is actually more fit for heavy service vehicles due to its durability and capacity to handle higher stress (weight) loads. Both of these systems are based on gear driven assemblies.
Rack-and-pinion steering, as its name implies, features a rack and pinion gear set, mounted inside the rack housing near the bottom of the steering column. The pinion gear is attached to the end of the steering shaft, with the pinion gear teeth engaged to the teeth along the rack. The ends of the rack protrude out of each side of the rack housing and connect to tie rods. The tie rods connect to steering arms located on each wheel spindle.
How does this setup work? When the wheel is turned, the pinion gear rotates and moves the rack to the left or right. If the steering wheel is turned left, the pinion rotates counter-clockwise (from the driver’s perspective) and pushes the rack to the right. This causes the tie rods and steering knuckles to push the right tire out and pull the left tire in, making the car turn left.
When the steering wheel is turned to the right, the opposite occurs. The pinion moves clockwise and pushes the rack to the left. The tie rods and steering knuckles pull the right tire in and push the left tire out, thereby turning the vehicle to the right.
Recirculating ball, sometimes referred to as recirculating ball and nut, features a specialized worm gear. Like the pinion gear, the worm gear connects to the end of the steering shaft and turns when the steering wheel turns.
The worm gear works with a sliding metal nut rack in a configuration resembling a nut and bolt. The worm gear is threaded, like a bolt, and twists inside a threaded hole at the center of the nut rack. On the outside of the nut rack are gear teeth that engage a cross shaft, called a sector shaft, connected to a moveable, swinging arm called a Pitman arm. When the worm gear turns, the nut rack slides to its front or back. As it slides, the nut rack’s outer teeth turn the sector shaft, forcing the Pitman arm to swing in an arc.
The swinging end of the Pitman arm connects to the center link (also called drag link or relay rod), which transfers this swinging motion to the tie rods and the steering arms. In the same way the rack shifts left or right to turn the wheels in a rack and pinion system, this motion forces the steering linkage to turn the wheels in the appropriate direction.
This recirculating ball system gets its durability, and its name, from the recirculating ball bearing system in the worm gear/nut rack configuration. Ball bearings roll through the worm gear threads in two outside loops called ball guides, and they recirculate through the gear as it turns. Because the worm gear never directly engages the threads in the nut rack, friction is reduced, allowing both the gear and nut to last longer. Because this setup greatly reduces stress on the gears, a vehicle equipped with it can weigh more and haul heavier loads than one equipped with a direct-contact, rack-and-pinion system.
The recirculating bearing setup also reduces steering slop. When a recirculating-ball steering wheel is turned in different directions, the gear teeth momentarily come out of contact with each other, producing a loose feeling in the wheel known as slop. The bearings fill in these areas of separation, restoring contact and diminishing this loose feedback.
Steering linkage
Along with their use of different gear sets, steering systems also use different steering linkages — the system of connecting parts and pivots between the steering gear and steering arms.
In rack and pinion systems, the steering linkage consists of two inner tie rods and two tie rod ends covered by rubber boots to protect their assemblies from dirt and debris. The inner tie rods attach to the steering rack ends, while the outer ends attach to the suspension arms on the steering knuckles. This setup connects the rack directly to the steering knuckle.
Recirculating ball-type steering gears require a more complicated linkage to transmit the rotary output of the sector shaft to the back-and-forth movement of the wheels. In most steering linkage arrangements, one end of the center link is supported in the Pitman arm, while a frame-mounted idler arm supports the other end. The idler arm pivots in a support attached to the frame when the steering linkage moves back and forth.
The center link connects to the tie rods, which connect to the steering arms. In these setups, the steering arms are part of the steering knuckle spindle assemblies. When the steering arm moves, the steering knuckle assembly rotates on the suspension control arm ball joints.
Most rear-wheel drive vehicles and pickup trucks with recirculating ball steering have a special linkage setup called parallelogram linkage. This linkage features a center link that always moves parallel to the axle. Parallelogram steering linkages may be mounted either on the front or rear of the vehicle.
Tie rods are used in linkages for both steering systems because of their movement capabilities. Tie rods are ball and socket devices. A spring or plastic spacer holds the ball in position in the socket, while the ball attaches to a tapered stud. The tapered stud fits into a taper in a steering arm and is held in position by a threaded nut. The ball and socket allows up-and-down movement between the tie rod and the steering arm as the vehicle goes over bumps. Tie rod length is adjusted via threaded sleeves, which are locked by clamps.
Power assist
Power steering works with both rack and pinion and recirculating ball in relatively the same manner. When the steering wheel is turned, a hydraulic pump forces fluid against the steering gears to assist the driver.
At the heart of power steering systems is the rotary valve. This valve typically sits at the base of the steering column, next to the steering gear. It connects to a rotary-vane pump run by pulleys connected to a motor. This pump forces hydraulic fluid in and out of the rotary valve to the steering gear.
The amount of fluid forced into the system is determined by the torsion bar, located inside the rotary valve. The torsion bar is a thin rod of metal that twists when force is applied to it. The top of the bar connects to the steering wheel, while the bottom connects to the pinion or worm gear. When the driver turns the wheel, force — or torque —is applied to the bar. The more torque the driver uses to turn the wheels, the more the bar twists and the greater the hydraulic pressure applied to the steering gears.
How does this system work? When the steering wheel is not being turned, the hydraulic lines running into the rotary valve provide the same amount of pressure to the steering gear. When the wheel is turned one way or the other, ports open up in the rotary valve to send high-pressure fluid rushing to the appropriate lines, which helps turn the wheels in the appropriate direction.
Some rack-and-pinion systems are fitted with electronically controlled power steering, which is designed to regulate the hydraulic steering boost according to vehicle speed. In these systems, electronic controls and an electric motor replace the hydraulic pump, hoses and fluid. The motor features an armature that the rack passes through. A ball nut with thrust bearing, also part of the motor, transfers the rotary motion of the armature to the linear movement of the rack. This extra “push” on the rack makes steering easier.
Diagnosis:
Identifying steering damage
Here is the best rule of thumb for diagnosing a damaged or potentially damaged steering system: Diagnosis begins when the vehicle first arrives at the shop and doesn’t end until several weeks after the owner picks it up. The reason for this extended diagnostic period lies in the fact that many of the steering system’s most important pieces — for example, the gears or the rack — are covered, sometimes making damage difficult to notice. In addition, some pieces do not show any signs of damage until after the vehicle is driven and normal road stresses are placed on them.
To diagnose steering damage, two basic tests are needed — a visual inspection and a road test. If the tech suspects that the power steering units are damaged, they should run a separate test on them with a steering system analyzer, which helps locate leaks. The visual inspection involves the interior steering pieces, the steering wheel and column, and the exterior parts.
There are a few things to keep in mind about diagnosis. First, there’s really no such thing as “typical” steering damage, especially if the vehicle has been in an accident. Every accident is different with regard to steering systems. Steering system damage is more about angles than velocity. A direct hard hit at a particular angle can produce light or no damage, while a relatively light hit at another angle can cause severe damage. Also, severe suspension damage doesn’t automatically imply heavily damaged steering components. This is also true in light hits.
When examining exterior parts, the linkage and hoses should be checked for tears, hairline cracks and breakage. If the vehicle has a Pitman arm, techs should shake it forcefully to check for any looseness. The same goes for other parts of the linkage and steering. Suspect parts should be pulled and pushed on to determine if they’ve been knocked out of position or need to be tightened or replaced.
On rack-and-pinion systems, it’s important for techs to check for loose or damaged ball sockets at the tie rods’ ends and where the tie rods attach to the rack. Power steering fluid leaks also may occur. Small leaks often are hard to detect because the fluid builds up inside the bellows and doesn’t show. Wiping the gear box and pump with a clean rag can help identify leaks.
After the underside of the vehicle has been inspected, it’s time for the interior. Cracks and bends to the steering wheel and column sometimes occur. If the airbag was deployed, there’s a good chance the steering wheel was damaged.
Once a vehicle is roadworthy, it needs to be taken for a sufficiently long test drive, 30 minutes at the very least, in different driving conditions and on different road surfaces. Because of time constraints during the day, it might be helpful for your shop customers to drive the vehicle home at night, especially if they have a long commute. During the drive they can check for any “dead spots” in the steering — areas where the steering seems ineffective. This is usually a sign of broken gear teeth. They can also listen for odd noises when the steering is turned and for loose pieces in the steering column. These types of sounds are sometimes difficult to detect on shorter drives.
Problems to look for include the following:
- Bump steering (steering veers to one side when vehicle hits a bump) — This may indicate the steering rack is not level or that the steering arms are bent. This also can occur if the parallelogram steering linkage is not level.
- Excessive steering wheel play — This is caused by loose or damaged steering linkages, tie-rod ends or damaged steering column bearings. It can also be caused by a damaged steering gear or loose steering gear bolts.
- Difficult or hard steering — Causes include a damaged steering pump or damaged steering column bearings, along with internal damage in the power rack assembly or seized steering column U-joints.
- Drifting or pulling — This can be the result of loose or damaged steering linkages, or a damaged steering gear valve. Or the vehicle may simply need a wheel alignment.
- Excessive road feedback— Causes include loose or damaged steering linkages, tie-rod ends, steering gear mounting bolts and column bearings. It may also be the result of loose or damaged steering column bearings.
- Failure to return to center position —This may indicate binding in the ball joints, steering gear and linkage. It also can be caused by unbalanced power assist, such as the power steering fluid not being routed in the correct direction.
- Off center steering wheel that doesn’t pull — The steering linkage may have been knocked off center when the toe was adjusted. Other causes include bent steering arms and linkage.
- Sticking or poor return — This can be caused by binding steering column bearings, a binding U-joint, and loose or damaged steering linkages and tie-rod ends.
- Wandering — This is caused by loose or damaged steering gear bolts, along with loose or binding steering linkages and tie-rod ends. Other causes include loose steering column U-joint bolts and improper steering gear preload adjustments.
When the test drive is over, the vehicle ought to be put back on the rack and all steering components should be carefully inspected for any evidence of leaking. During this process, the steering wheel should be turned all the way to the right and left, making sure the wheels turn with it appropriately.
When the vehicle is returned to its owner it’s smart for your shop customers to advise them to be on the lookout for any unusual conditions. To help prevent false alarms, give your customers specific conditions to pass along — rattling noises, pulling, difficult steering, etc. (Perhaps you can put together a checklist that they can hand out with simple descriptions. Steering systems could be just one component of this checklist.) Vehicles might feel odd or unfamiliar at first simply because they haven’t been driven for a while.
Repair tips
After steering system damage is located, the greatest challenge will be determining the correct repair. When you examine the above list of problems to look for during a test drive, note how one problem can have numerous causes or numerous combinations of causes. When performing repairs, the primary goal is to be thorough. Techs really need to make all the necessary repairs and solve the source of a problem, not just one of the symptoms.
For example, consider what can happen when a vehicle with recirculating ball steering and parallelogram linkage is wrecked. During an accident when the driver has turned the wheels fully in one direction (usually to avoid the collision), a curb or other object can strike the wheels in that same direction. This can twist the sector shaft and prevent the steering wheel from returning to a centered position.
In some of these cases, a technician will notice the off-center wheel and repair it by performing a wheel alignment. While the wheel remains centered, the real problem remains — the sector shaft is twisted and weakened so it may break and disable the steering at a critical time when the vehicle is being driven.
To avoid making this mistake, techs should always look at the splines where the shaft comes out of the steering box. The splines should be straight. If not, the sector shaft probably is bent. Another indication of a bent sector shaft is the steering being off-center while the vehicle is driven straight and the toe is correctly adjusted (also assuming there is not a rear thrust angle problem).
A twisted sector shaft must be replaced, either by replacing the sector shaft alone or by replacing the gear box with a rebuilt, new or salvaged unit. If the sector shaft needs to be replaced, know that some vehicle makers refer to it as a Pitman shaft.
To further assist you, I-CAR offers the following repair tips that you can pass on to customers:
n Damaged dust boots on tie-rod ends and rubber bellows or boots where the tie rods enter the rack should always be replaced. A damaged boot or bellow will allow dirt in and cause premature failure of the ball socket.
n When an inner tie-rod is replaced, the rack must be properly supported. It’s a good idea for techs to ask others in the shop for help. The bellows on both sides typically need to be loosened to allow access to the rack itself. If the rack is not held stable while the bellows are loosened, it can be damaged.
n If the toe needs to be aligned and a wheel has been damaged in a collision, tell your customers to look for a damaged steering arm on the knuckle. This is another problem that is frequently misdiagnosed and repaired by adjusting the tie rod end. If the steering arm remains bent and the toe is reset, the toe adjustment will be off and create problems with the Ackerman steering or turning radius. During a turn, the inside wheel is designed to turn at a greater angle than the outside wheel. This is because the circle that the inside wheel turns on is smaller than the outside wheel. If the steering arms are bent, the change in geometry produces a turning radius different from the radius the vehicle was designed for. This can cause scrubbing of the tires as a corner is negotiated. Prevent this problem by checking the steering arms for signs of damage, such as flaking coatings or rust on the knuckle where the steering arm protrudes. A straight edge can be used to measure from the steering arm to the tie-rod end. Technicians should compare the measurement to a measurement taken on the opposite side of the vehicle.
n When it comes to bent pieces in the airbag system, “never repair and always replace.” The system is extremely sensitive to the slightest changes.
n Steering linkage parts are manufactured from malleable materials and are designed to bend or deflect rather than fracture under extreme stress loads. This toughness and malleability are necessary to avoid the complete loss of control that would occur if any part of a steering linkage were to break. Steering linkage parts therefore must never be heated during a repair because it could cause them to lose their malleability and fracture.
Turn a shop in the right direction
If, upon review, a shop lacks a proper approach to steering repairs, make sure they don’t panic. The directions and resources necessary to raise their level of performance are readily available. Along with I-CAR courses, they can receive service help from vehicle manufacturers and product information from engineering companies. From there, the path they take entirely depends on how much time and effort they want to place on these repairs. Certainly, these procedures are complex. And doing them properly demands plenty of patience and dedication. But considering the payoff in satisfied and safe customers, the reward certainly is more than worth the effort.
About the Author
Tim Sramcik
Tim Sramcik began writing for ABRN over 20 years ago. He has produced numerous news, technical and feature articles covering virtually every aspect of the collision repair market. In 2004, the American Society of Business Publication Editors recognized his work with two awards. Sramcik also has written extensively for Motor Age and Aftermarket Business World. Connect with Sramcik on LinkedIn and see more of his work on Muck Rack.