The car’s steering gear works in secret and rarely causes problems. Only when there are clear symptoms of a defective steering gear does the component become noticeable. In our guide, you will find out which symptoms occur with a defective steering gear, what the causes are and how the component can be replaced.

How the power steering gearbox works

The steering gear is an important component of the steering of modern cars. The task of the steering gear is to convert the rotary movement of the steering wheel into a sliding movement. Only in this way can the wheels of the vehicle be shifted to match the steering movement of the driver. In addition, the transmission dampens the effects of the road on the steering wheel. In cars and light commercial vehicles, steering gears with a toothed rack are usually used.

Steering gear determines the steering angle of the front wheels

All movements from the steering wheel are transmitted via the steering column to the steering gear. From here, the force is transmitted as a pushing movement via the steering linkage to the other components of the steering system. When the driver turns the steering wheel, the steering angle of the front wheels changes. The transmission ratio of the steering gear reduces the amount of force required for this.

Steering gear and servo make steering easier

In order to further reduce the amount of power required, the steering gears of modern vehicles almost always feature steering assistance by means of a servo. Hydraulic components integrated into the steering gear amplify the driver’s steering movements. A servo pump generates the necessary pressure to support the steering function as required.

Typical symptoms of a defective steering gear

The steering gears of modern vehicles are heavy-duty and robust. Nevertheless, the steering gear in the car can also break down once in a while. If the steering gear is defective, typical symptoms usually indicate the problem. The exact signs depend not least on the type of steering gear and its design.

One of the common signs of a defective steering gear is that the steering suddenly becomes sluggish. The driver has to exert much more force to steer the car. The steering wheel may also become difficult to turn. In some cases, the car can no longer be steered precisely or the steering locks up completely if the steering gear is defective.

Oil loss or noise development

Steering gears with integrated steering assistance as power steering or electro-hydraulic steering gears often draw attention to the defect through oil loss. Here, a pool of oil can sometimes be seen under the affected vehicles. There may also be servo oil under the vehicle floor and on the steering gear, indicating a defective steering gear.

If you suspect that the steering gear might be defective, you should also pay attention to abnormal noises when steering. Often, a broken steering gear makes unusual steering noises, such as a grinding or cracking sound that can occur when steering. A whirring sound when moving the steering wheel can also be one of the symptoms of defective steering gears.

Signs of a defective steering gear

• Vehicle steering is sluggish
• Increased steering effort
• Steering assistance fails
• Steering wheel is locked
• Straight line driving is imprecise
• Noise or crackling when steering
• Whirring during steering movements
• Error messages steering gear or steering angle sensor
• Steering play is increased

Common causes of a defective steering box

A defect in the steering gear can occur due to various causes. If the steering gears of older vehicles are defective, wear and tear and the age of the components can be considered as the cause. All components inside a steering gear wear out with every steering movement, which can ultimately lead to a defect.

Various stresses caused by driving can also cause the steering gear to become defective. Bad roads or driving off the beaten track transmit shocks and vibrations to the steering gear. This can cause components to wear out or become worn, causing the gearbox to wear out over time.

Accident or defective components as cause

Accidents can also be a possible cause of steering gear failure. If steering components such as tie rods are hit, this can also damage the steering gear. In addition, the steering gear under the vehicle is exposed to greater loads due to wetness and dirt. If moisture penetrates, for example, the steering gear suffers.

A defect in other components of the vehicle can also lead to a broken steering gear. For example, the gearbox can be damaged by defective tie rods. Unbalanced wheels or worn chassis components can also promote wear of the steering gear. If, on the other hand, oil leaks from the steering gear, hardened sealing rings are usually the cause.

Therefore the steering gear is defective

• Wear due to high mileage
• Wear and tear due to poor road surfaces
• Accidental damage to the steering gear
• Defect due to moisture penetration
• Seals or gaskets are worn
• Damage due to defective tie rods
• Load due to unbalanced wheels

Steering gear defective – better replace promptly

If there are first signs of a defect in the steering gear, the problem should be remedied promptly. A replacement of the complete component is usually unavoidable for reasons of driving safety. In addition, a broken or leaking steering gear can cause consequential damage to the servo pump or servo motor, which can be avoided by replacing the steering gear.

Steering gear repair

If the steering gear is defective, it cannot be repaired easily. The internal structure and function of the components are complex, and wear on the gears and pinions as well as the steering rack is often already well advanced. Therefore, instead of repairing the steering gear, it is usually better to replace the entire steering gear.

Buy steering gear new or used

Steering gears are offered as new parts, as used spare parts and as replacement steering gears. Some specialist companies have specialised in the repair of steering systems and have made it their business to overhaul all types of steering gears. In this process, a defective steering gear is completely disassembled in order to be able to replace components such as the gearwheel and steering rack. Especially for older vehicles, the installation of a used steering gear is a good and inexpensive alternative.

Replacement of a defective steering gear

A defective steering gear can usually be easily replaced with an intact spare part. Since the gearbox is a safety-relevant component, this repair should only be carried out by skilled persons. The exact procedure may vary depending on the type of steering gear. A lifting platform is helpful to be able to change the component under the vehicle.

1. Prepare the replacement of the steering gear: Before the replacement of the steering gear can begin, certain preparations must be made. This includes the dismantling of some components, such as parts of the chassis or the exhaust system. Rusty parts and screw connections should be cleaned with a wire brush or treated with rust remover.
2. Removing the steering gear: The defective steering gear is removed next. This usually involves detaching the track rods from the steering knuckles. The connecting lines of the power steering must also be dismantled. Any leaking servo oil must be collected. After loosening all the fastening points, the steering gear can be removed from underneath the car.
3. Install the steering gear: The next step is to install the new steering gear. Depending on the version, components of the old steering gear must be taken over beforehand. Then install the steering gear in the vehicle in reverse order. It is important to observe all tightening torques specified by the manufacturer and to work carefully.
4. Completing the repair: After installing the steering gear, the servo fluid must be refilled and the system bled. Since components of the chassis have been loosened and with the new steering gear an essential part of the vehicle steering has been replaced, a wheel alignment should be carried out after the intervention.

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