Steering Wheel Turns, But Wheels Don’t?
Your car’s steering wheel is your lifeline on the road, the vital link between your intentions and where your vehicle goes. But what if that link were suddenly severed?
A steering wheel that suddenly spins freely without actually turning the front wheels is rare but can be a nightmare scenario if it happens while driving. Read on to understand the potential root causes and how much it’s going to cost to fix.
Causes of a Steering Wheel That Spins Freely, Yet Wheels Don’t Move
A lack of vehicle wheel end movement, despite being able to freely turn the steering wheel can be caused by one of several potential underlying issues. While these issues differ in complexity to resolve, most are easily identified.
1) Failed Steering Gearbox
Many trucks and vans utilize gearbox-based steering systems. While hearty, gearboxes of this type do fail internally on occasion. If the internal gear set within a vehicle’s steering gearbox were to shear or otherwise fail, it is possible for a lack of output shaft rotation to result.
2) Faulty Power Steering Rack
Virtually all passenger cars on the road today feature rack and pinion steering systems. An internal failure of a rack’s pinion gear set, or a catastrophic failure of the rack gear train can cause the rack itself to not respond to rotational input forces applied by a vehicle’s steering shaft.
3) Compromised Steering Shaft
A vehicle’s steering shaft is a piece of essential hardware that transmits rotational force from the steering wheel to the input side of the steering gearbox or rack. A failure of this shaft, or its U-joints will certainly prevent a vehicle from being steered in any meaningful way.
4) Failed Steering Linkage
You may also encounter a steering linkage failure, effectively preventing your vehicle’s wheels from being turned by mechanical means. This occurs when a vehicle’s tie-rod ends, drag link, pitman arm, etc., fail, often due to collision or unanticipated impact.
BEWARE of False Online Information
Avoid falling prey to questionable information found on the internet, often cited from unreliable sources. When speaking on the subject of steering-related issues that result in a lack of wheel-end control, it is important to understand that power steering pump failure is not a probable cause.
In truth, a power steering pump issue is far more likely to cause heavy steering, rather than unresponsive steering. The same can be said for issues that can have an effect on power steering fluid pump operation. These conditions include serpentine belt failure and low power steering fluid levels.
Again, these conditions would simply stifle the hydraulic assist function that the power steering system provides, not create a complete inability to index a vehicle’s wheels.
Can This Happen During a Drive?
A steering-related failure can occur while driving, though such events are rare, especially in light of regular inspection and periodic maintenance. The most common failures of this type that happen while driving, are those related to damaged or excessively worn steering linkage.
How Power Steering Works
A vehicle’s steering system, while brilliantly engineered, is not overly complex in nature. The steering wheel that you hold in your hand is connected to a steering gearbox or steering rack via a steering shaft.
This shaft features U-joints that allow it to pivot without binding. The rotational force exerted on this steering shaft is then imparted upon the steering gearbox/rack. Modern automotive applications, featuring power steering, use hydraulic pressure to assist in effortlessly turning a vehicle’s wheels.
With the aid of this hydraulic pressure, the mechanical forces exerted upon a vehicle’s steering gearbox or rack are amplified.
In applications featuring a steering gearbox, an output shaft-mounted pitman arm indexes in response to rotational forces applied at the gearbox’s input shaft. Affixed to the other end of this pitman arm is a linkage known as a drag link.
The drag link itself anchors to a knuckle and hub-integral steering arm, through which wheel-end movement is transferred. This movement is evenly exerted between both front wheels via an adjustable tie-rod.
On the other hand, steering systems of a rack and pinion design transfer force exerted at the pinion input shaft, into amplified force at opposing output shafts. Affixed to these output shafts are tie-rods, which feature adjustable outboard tie-rod ends.
The tie rod ends themselves are bolted to hub-integral steering knuckles. Rotational movement is allowed for at each wheel end by ball joints, of a ball-and-socket construction. Here’s an interesting (and fun) video showing how a hydraulic power steering system works:
Electric Power Steering: Additional Considerations
If an EPS-equipped vehicle experiences the “steering wheel turns, but wheels don’t” issue, potential causes include:
1. Faulty electric motor – Unlike hydraulic systems, a failed EPS motor won’t provide any assistance.
2. Malfunctioning torque sensor – This can prevent the system from detecting steering input.
3. Control module failure – The computer managing the EPS might not send correct signals to the motor.
4. Wiring issues – Electrical problems can disrupt communication between components.
While EPS eliminates some traditional failure points like hydraulic pumps and fluid leaks, it introduces new electrical and electronic components that can fail. Diagnosing these issues often requires specialized equipment to read error codes and test electrical components.
As with hydraulic systems, mechanical failures in the steering rack or linkages can still cause wheels to remain stationary despite steering input. This makes regular inspections just as important to prevent unexpected steering failures.