Steering

9 Lessons

From rack and pinion to electric power steering — diagnose steering complaints with confidence.

Overview

The steering system translates driver input into wheel direction. This module covers rack and pinion, recirculating ball, hydraulic power steering, electric power steering (EPS), steering columns, and the components that wear out and cause complaints like wandering, pulling, and noise.

Lessons

LESSON 01

Steering System Overview

The steering system lets the driver control the direction the front wheels point. You turn the steering wheel inside the cabin and that rotation is transmitted through the steering column, through a gear mechanism, and out to the front wheels through tie rods that push and pull the steering knuckles left and right. Every component in this chain must be tight and precise — any looseness or play shows up as wandering, pulling, or imprecise steering that the driver feels immediately.

Rack and pinion

The most common steering gear on modern vehicles. The steering column connects to a pinion gear — a small round gear with teeth. That pinion meshes with a rack — a long flat bar with teeth cut into it that runs side to side across the front of the vehicle. When you turn the steering wheel, the pinion rotates and the rack slides left or right. Tie rods on each end of the rack connect to the steering knuckles at the front wheels. Rack and pinion is simple, direct, and gives precise steering feel. When a rack and pinion develops internal wear, you feel looseness or play in the steering wheel — a dead spot in the center where you can turn the wheel slightly before the wheels respond.

Electric Power Steering — EPS

Most modern vehicles use an electric motor instead of a hydraulic pump for power assist. The EPS motor is mounted either on the steering column or directly on the rack. A torque sensor on the steering column measures how hard the driver is turning. The EPS module uses that input along with vehicle speed to determine how much assist to provide. At low speed — parking lot maneuvers — maximum assist. At highway speed — minimal assist for better road feel. EPS has no fluid to leak, no belt to wear, no pump to fail, and no parasitic engine load. It also allows the vehicle's stability control system to apply small steering corrections automatically.

Recirculating ball — truck steering

Trucks and older vehicles use a steering gearbox with a recirculating ball mechanism instead of rack and pinion. A worm gear inside the box turns a sector gear that moves a pitman arm. The pitman arm connects through a linkage of center links, idler arms, and tie rods to the front wheels. This system handles the higher steering forces of heavy trucks. Wear in the gearbox, pitman arm, idler arm, or any linkage component causes steering play. Adjustment may be possible at the gearbox sector shaft — but excessive play usually means component replacement.

LESSON 02

Tie Rods — Inner and Outer

Tie rods are the final link between the steering gear and the wheels. They transmit the lateral movement of the rack to the steering knuckle. Each side has an inner tie rod that connects to the rack end and an outer tie rod that connects to the steering knuckle. The outer tie rod threads onto the inner tie rod with a jam nut that locks the adjustment — this is how toe alignment is set.

How tie rods wear

Each tie rod end has a ball-and-socket joint. Over time and mileage, the ball wears inside the socket and develops play. That play translates directly into steering looseness. Worn outer tie rod ends are one of the most common causes of wandering steering and inner edge tire wear from toe that drifted out of specification.

Inspection — loaded suspension

Put the vehicle on a drive-on rack or lift it and support it under the control arms so the suspension is loaded in its normal position. Grab the tire at 9 o'clock and 3 o'clock — the sides. Push in with one hand and pull out with the other, then reverse. Any clicking or movement between the tie rod and the knuckle indicates a worn outer tie rod end. To check the inner tie rod, grab the inner tie rod boot at the rack and try to push and pull the tie rod in and out. Any movement indicates inner tie rod wear. Never check tie rods with the wheels hanging free — the unloaded suspension masks the play.

Replacement and alignment

When replacing a tie rod end, always count the number of exposed threads or measure the distance from the jam nut to the tie rod end before removal. Set the new one at the same measurement. This gets the toe close enough to drive to the alignment machine safely. A full alignment is required after any tie rod replacement — do not return the vehicle without it.

LESSON 03

Ball Joints in Steering

Ball joints are the pivot points where the steering knuckle connects to the control arms. They allow the knuckle to pivot left and right for steering while also moving up and down with suspension travel. They handle forces in multiple directions simultaneously — the full weight of the vehicle corner, lateral cornering forces, and braking forces all pass through the ball joints.

Load-bearing vs follower

The load-bearing ball joint carries the vehicle weight through the spring — whichever control arm the spring sits on has the load-bearing joint. On most MacPherson strut vehicles, the lower ball joint is the load-bearing joint. On double wishbone designs, it depends on which arm carries the spring. The load-bearing joint wears faster because it is always under pressure. The follower joint — on the other arm — positions the knuckle but does not carry the vehicle weight.

How to check them

Drive-on rack. Suspension loaded. Grab the tire at 12 and 6 o'clock — top and bottom. Push in at the top while pulling out at the bottom, then reverse. Movement indicates ball joint wear. You can also place a pry bar under the tire and lift while watching the ball joint — any separation between the ball and the socket is visible. Specifications vary — some manufacturers allow a small amount of measured play while others require zero perceptible movement. Always check the manufacturer specification before condemning.

A severely worn ball joint can separate under load — the wheel folds under the vehicle and you lose all steering and braking control on that corner. Ball joint play is a safety concern that requires immediate attention. Never tell a customer it can wait if the joint has excessive play.

LESSON 04

Power Steering Fluid and Hydraulic Systems

Hydraulic power steering systems — found on older vehicles and many trucks — use a belt-driven pump to generate hydraulic pressure. A rotary valve in the rack or gearbox directs that pressure to the appropriate side of a piston based on which way you are turning, multiplying your steering effort.

Fluid — check it first always

Low fluid or contaminated fluid causes almost every power steering noise and performance complaint. Check fluid level with the engine off — the reservoir has HOT and COLD marks. Use the correct specification fluid — power steering fluid, ATF, or synthetic depending on what the manufacturer requires. Using the wrong fluid damages seals and accelerates pump wear. Dark brown or black fluid with a burnt smell indicates the system has overheated and the fluid has broken down — flush and refill.

Whining noise

A whining noise that increases with engine RPM and gets louder when you turn the wheel is the power steering pump. Low fluid level is the first thing to check — air in the system from low fluid causes the pump to whine and foam the fluid. If fluid is full and correct, the pump is worn internally. Pump output pressure and flow testing against manufacturer specification confirms pump condition.

Steering effort complaints

Hard to turn at all speeds — low fluid, failed pump, or broken drive belt. Hard to turn only at low speed and easy at highway speed — the pump may be producing enough pressure for highway driving but not enough volume for low-speed parking lot turns. Pump volume output drops as the pump wears. Hard to turn in one direction only — the rotary valve in the rack or gearbox is sticking or the rack has an internal seal failure on one side.

LESSON 05

Steering Angle Sensor and Calibration

The steering angle sensor — SAS — is mounted on the steering column, usually behind the steering wheel inside the clock spring assembly. It tells the stability control system and the EPS module exactly what angle the steering wheel is at and how fast it is being turned. This is not optional information. Without an accurate SAS reading, stability control cannot calculate whether the vehicle is going where the driver intends or sliding out of control. On EPS vehicles, the SAS also helps the module determine how much assist to provide and in which direction.

How the sensor works

Most steering angle sensors use optical or magnetic encoding. Inside the sensor housing, a disc or ring with a pattern of slots or magnetic poles rotates with the steering column. A reader — either an optical pickup or a Hall effect sensor — counts the changes in the pattern as the wheel rotates. The module tracks absolute position, rotation speed, and direction. Some sensors use two channels to provide redundancy. If the two channels disagree, the module sets a fault code and disables stability control because it cannot trust the data.

When calibration is required

After any alignment. After any steering component replacement — tie rods, rack, column, intermediate shaft. After a battery disconnect on some vehicles. After any repair that changes the relationship between the steering wheel position and the front wheel direction. An uncalibrated SAS causes stability control faults, EPS faults, and incorrect steering assist that makes the vehicle feel different turning left versus right. The SAS must know that the steering wheel pointed straight ahead corresponds exactly to the front wheels pointed straight ahead. If that relationship is off — even by a few degrees — the system does not work correctly.

How to calibrate

The exact procedure varies by manufacturer. Some require a scan tool to zero the sensor with the steering wheel centered and the wheels pointed straight ahead. Some require a specific driving procedure — turns at specific speeds. Some self-calibrate after clearing codes and driving in a straight line. Always look up the specific procedure for the vehicle you are working on. Do not skip this step — an alignment without SAS calibration on a vehicle that requires it means the vehicle comes back with a stability control light. On many vehicles, the calibration must be performed with the vehicle on flat level ground, engine running, and the steering wheel perfectly centered before initiating the scan tool procedure.

LESSON 06

Diagnosing Steering Complaints

Steering wander — vehicle does not track straight

Check tire pressures first — uneven pressure causes pull. Check alignment — toe out of spec is the most common cause. Inspect tie rod ends and ball joints for play. On hydraulic systems, check for a binding rack valve. On EPS, scan for codes — a torque sensor fault changes assist behavior.

Steering vibration or shimmy

A vibration in the steering wheel at a specific speed range — usually 55 to 70 mph — is almost always a tire balance issue. A shimmy or oscillation at low speed after hitting a bump — the tie rods, ball joints, or strut mounts may have enough play to allow the front wheels to oscillate. Check all front-end components for play on a drive-on rack.

Clunk when turning the wheel

A clunk or pop felt through the steering wheel when turning — especially from straight ahead to a turn — points to a worn intermediate steering shaft coupler, a worn strut mount bearing, or a worn tie rod end. Turn the wheel slowly left and right while someone watches each component for the source of the movement.

EPS warning light

Scan the EPS module for codes first. The most common EPS codes relate to the torque sensor, motor current, and communication faults. A torque sensor code often traces to a faulty clock spring — the spiral ribbon cable in the steering column that provides electrical connections while allowing the wheel to turn. Check the clock spring connector and the column connections before condemning the EPS module. Always calibrate the steering angle sensor after any EPS repair.

LESSON 07

EPS Motor Types

Electric Power Steering replaces the hydraulic pump, hoses, fluid, and belt with a single electric motor and a control module. No fluid to leak. No belt to snap. No parasitic drag on the engine. The motor provides steering assist only when you actually turn the wheel, which saves fuel compared to a hydraulic pump that runs constantly. But not all EPS systems put the motor in the same place, and where the motor lives changes how the system feels, how much assist it can provide, and what fails.

Column-assist EPS

The motor mounts on the steering column inside the cabin, between the steering wheel and the firewall. It applies assist torque directly to the steering column shaft. Think of it like someone grabbing the steering shaft below the dash and helping you turn it. This is the most common type on smaller vehicles — compact cars and economy sedans. The advantage is that the motor is protected from road debris, water, and temperature extremes because it lives inside the vehicle. The disadvantage is that the motor works against the friction of the entire steering system downstream — the intermediate shaft, the rack, and the tie rods. On heavier vehicles, the column motor would need to be too large to provide enough assist, which is why bigger vehicles use a different approach.

Rack-assist EPS

The motor mounts directly on the steering rack housing. It drives a ball screw mechanism that pushes the rack left and right, adding force directly where it is needed. Think of it like someone pushing the rack for you. Because the motor acts directly on the rack, it can provide more assist with less effort. This is used on mid-size and larger vehicles, SUVs, and trucks that need more steering force than a column motor can deliver. The trade-off is that the motor sits under the vehicle where it is exposed to water, road salt, and debris. The motor and its connections must be sealed and protected.

Dual-pinion EPS

This design uses two pinion gears on the rack. One pinion connects to the steering column — the driver input. The second pinion is driven by the EPS motor. Both pinions mesh with the same rack but at different locations. The driver turns one pinion. The motor turns the other pinion to add assist force. This separates the driver feel from the motor assist so engineers can tune each independently. The result is a more natural steering feel. This design is used on some premium and performance vehicles where steering feedback matters.

The torque sensor — how the motor knows what to do

Every EPS system has a torque sensor on the steering column. This sensor measures exactly how much twisting force the driver is applying to the steering wheel and in which direction. The sensor typically uses a torsion bar — a thin steel bar that twists slightly under load. Magnetic or optical sensors measure how much the bar twists and report that to the EPS module. The module combines that torque reading with vehicle speed data from the ABS module to calculate how much assist to provide. Low speed, high torque input — maximum assist. Highway speed, light torque input — minimal assist. If the torque sensor fails, the module has no idea how hard you are turning or which direction. Most systems disable assist entirely and set a warning light rather than guess wrong.

LESSON 08

Torque Sensor Operation

The torque sensor is the brain input for the entire EPS system. Without it, the EPS motor does not know when to help you, how much to help, or which direction to push. It is the single most critical sensor in the power steering system. Understanding how it works helps you diagnose why the EPS light is on and the steering suddenly feels like you are arm-wrestling the vehicle.

How the torsion bar sensor works

Inside the steering column, a thin torsion bar connects the input shaft — the side the steering wheel attaches to — and the output shaft — the side that goes down to the steering gear. When you apply force to the steering wheel, the torsion bar twists slightly. The amount of twist is proportional to how hard you are turning. Two rings with magnetic patterns or optical markers are mounted on the input and output sides. As the torsion bar twists, the two rings rotate relative to each other by a tiny amount. Sensors read the relative position of the rings and calculate the applied torque. The twist is very small — a few degrees at most — and the torsion bar springs back to center when you let go of the wheel.

What the module does with the data

The EPS module reads the torque sensor signal hundreds of times per second. It combines that with vehicle speed from the ABS module. At parking lot speeds — say 5 mph — the module commands maximum motor assist because the tires are fighting the full friction of the pavement and the driver needs all the help possible. At highway speeds — 70 mph — the module provides very little assist because the tires are rolling with minimal scrub and the driver needs precise feedback, not amplified input. Some systems also factor in steering angle rate — how fast you are turning — to provide progressive assist during quick maneuvers like lane changes.

What happens when it fails

When the torque sensor fails or sends an implausible signal, the EPS module cannot trust the data. It does not know if you are turning left, turning right, or sitting still. The module disables the assist motor entirely and turns on the EPS warning light. The steering still works — it is mechanically connected — but you lose all power assist. On a vehicle with rack-assist EPS, the steering becomes extremely heavy, especially at low speed. Some drivers mistake this for a locked steering column. On some vehicles, an intermittent torque sensor fault causes the assist to cut in and out unpredictably, which feels dangerous because the steering effort changes without warning.

Calibration and replacement

Some torque sensors are integrated into the steering column and require column replacement. Others are replaceable as a separate component. After any torque sensor replacement or any repair that involves separating the steering column, the torque sensor must be calibrated. The calibration procedure tells the module what the sensor reads when zero torque is applied — the neutral position. Without calibration, the module may read a constant offset and provide assist in one direction even with the wheel centered. The calibration typically requires a scan tool, the steering wheel centered, and the wheels pointed straight ahead on level ground. Some manufacturers require a specific driving procedure after the scan tool calibration to complete the learning process.

LESSON 09

Intermediate Shaft

The intermediate shaft is the steel shaft that connects the steering column — inside the cabin — to the steering gear — under the hood or under the vehicle. It passes through the firewall and transmits the driver's steering input from the wheel down to the rack or gearbox. Most people never think about it until it starts making noise. Then it becomes the most annoying component on the vehicle.

Why it has universal joints

The steering column and the steering gear are rarely in a straight line. The column comes down from the dash area at one angle. The rack sits low on the subframe at a different angle. The intermediate shaft bridges that angle difference using one or two universal joints — the same type of U-joint concept used in a driveshaft. These joints allow the shaft to transmit rotation even though the input and output are not aligned. Some vehicles use a rag joint — a flexible rubber coupling — instead of or in addition to a U-joint. The rag joint absorbs vibration and provides a small amount of isolation between the steering gear and the steering wheel.

The clunk — the most common complaint

The number one complaint related to the intermediate shaft is a clunk or pop felt through the steering wheel when turning from center, especially at low speed. This clunk comes from wear or dry lubrication in the U-joints or splined connection of the intermediate shaft. Over time, the grease inside the joint dries out or washes away and the bearing caps develop play. That play shows up as a distinct clunk at the point where the steering reverses direction — straight ahead to a turn, or turning left and reversing to the right. On many GM trucks and SUVs, this is one of the most common steering complaints. Some manufacturers offer updated intermediate shafts with better lubrication or revised joint designs as a service fix.

Diagnosis

To confirm the intermediate shaft is the source, have someone sit in the vehicle and slowly turn the steering wheel left and right while you watch and feel the intermediate shaft from under the hood. Place your hand on the shaft near the U-joint. You will feel the clunk through the shaft at the exact moment the driver feels it through the steering wheel. If the noise and movement are at the U-joint, the shaft needs replacement. If the noise is at the rag joint connection to the rack, the rag joint may be worn or the rack mounting bolts may be loose.

Why it matters for steering feel

The intermediate shaft is not just a noise concern. Worn U-joints introduce play into the steering system that the driver feels as a dead spot — a range of steering wheel movement that produces no response at the wheels. This dead spot makes highway driving feel imprecise and can mask small steering inputs during emergency maneuvers. A worn intermediate shaft also affects steering angle sensor accuracy because the sensor reads the column position, but if the shaft has play, the column position and the actual wheel position do not match perfectly. After intermediate shaft replacement, always check and recalibrate the steering angle sensor and verify alignment.

Key Components

Steering rack and pinion
Power steering pump (hydraulic)
Electric power steering motor
Tie rods (inner and outer)
Steering column and intermediate shaft

How It Works

When you turn the steering wheel, rotational input travels through the steering column and intermediate shaft to the steering gear. The gear converts rotational motion to lateral motion, moving the tie rods, which turn the wheels. Power assist (hydraulic or electric) reduces the effort needed to turn.

Common Problems

Tie rod end wear causing loose steering
Power steering pump whine from low fluid
EPS motor failure or torque sensor issues
Intermediate shaft clunk on turns
Rack seal leaks

Diagnostic Tips

Dry park test — turn wheel with vehicle stationary and feel for play
Power steering fluid should never be low — find the leak
EPS calibration may be needed after component replacement
Check intermediate shaft U-joints for binding

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Steering

Overview

Lessons

Key Components

How It Works

Common Problems

Diagnostic Tips

Want to Dig Deeper?

Related Systems

Braking

ABS and Electronic Chassis

Suspension