In a vehicle’s technical systems, the steering system determines direction of travel, so it’s super important for safety. The chassis system affects steering response and feel during cornering. Together they define the overall handling of the vehicle.
Advanced steering systems like Variable Gear Ratio Steering have been used in sports cars like the Honda S2000 type V, which is a car with this tech.
Within the chassis system, one of the key configurations that affects cornering response and steering feel is the Variable Gear Ratio Steering (VGRS).
Let’s take a closer look at VGRS:
What Is Variable Gear Ratio Steering?
Variable Gear Ratio Steering (VGRS) is a steering technology that can adjust steering sensitivity according to different driving conditions. It can also adapt its steering response according to the driving mode selected, so you get optimal comfort and safety whether you’re cruising at low speeds or high speeds.
A fixed gear ratio can’t adapt to different speeds. Unlike fixed systems, a variable ratio system changes the gear ratio at different points in the steering wheel’s rotation, so you get more control and handling.
A variable gear ratio system adjusts the gear ratio based on vehicle speed and driving conditions. At low speeds it gives you faster wheel response for better maneuverability, at high speeds it gives you smoother control and more lane stability. Variable ratio steering adjusts the gear ratio along the rack to further improve handling and responsiveness.
How Variable Steering Ratio Is Achieved
The steering system consists of the steering wheel, universal joints, gears and rack. A Variable Steering Ratio (VSR) system adjusts the gear ratio by combining mechanical components with electronic control, so you get both handling and driving stability.
When you turn the steering wheel, torque is transmitted through the steering column to the pinion gear. The pinion engages with the rack, converting rotational motion into lateral movement that turns the wheels. In a VSR system, the input shaft’s gear ratio can be adjusted—often by a DC motor driving a worm gear—to change steering response and sensitivity.
An important parameter in steering is the “lock-to-lock” range, which is how many full turns the steering wheel makes from one extreme position to the other. This affects the vehicle’s maneuverability in tight spaces.Through mechanical design and electronic control, the VSR system adjusts the steering ratio according to driving conditions. At low speeds it increases the steering ratio to reduce effort and improve precision during parking or tight cornering. At higher speeds it lowers the steering ratio to improve steering accuracy and vehicle stability.
Advanced steer-by-wire systems, including those with innovative steering wheel designs like yoke wheels, benefit from VSR to further improve safety, driver control and comfort.
For performance oriented vehicles like race cars, a low steering ratio is used to give quicker and more responsive steering—essential for high speed driving.
1. Mechanical Optimization: Variable-Pitch Rack Design
The rack is designed with denser teeth in the center and wider spacing towards the ends, so it produces different response characteristics:
Center region: Denser pitch, slower response – ideal for high speed driving.
Outer regions: Wider pitch, quicker response – makes cornering lighter and easier.
This is simple and cost effective but can’t adjust to speed or other dynamic factors, so it’s limited in adaptability.
2. Electronic Control: Harmonic Drive Actuator
An electric control unit (harmonic reducer) is added to the steering column, using a motor and flexible gear assembly to adjust the output steering angle dynamically.
The system monitors vehicle speed, steering angle, torque, body slip and yaw rate in real time. A customized ECU algorithm adjusts the steering ratio and assist level so you get agile handling, smooth return-to-center, natural road feel and seamless integration with Advanced Driver Assistance Systems (ADAS).
This gives significant gains in agility, safety and driving comfort.
3. Steer-by-Wire Systems
The latest steering technologies, like DAS (Direct Adaptive Steering), remove the mechanical link between steering wheel and wheels entirely.
Operating principle:
Steering inputs are transmitted via sensors to the ECU, which controls electric motors to turn the wheels. At the same time, feedback motors simulate steering feel on the wheel, so you get a natural sensation while having full flexibility in steering ratio settings.
By combining these technologies, Variable Gear Ratio Steering (VGRS) is the ideal choice for modern vehicles, especially those with ADAS. It improves safety, reduces driver fatigue and gives higher handling performance without sacrificing natural steering feel.
An XEPS senior engineer said:”Our variable gear ratio system is designed for future intelligent vehicles. It balances high speed stability with urban agility, a refined and reliable steering experience.”
Engineered for OEM Integration
XEPS’s VGRS solutions are already implemented across multiple steering architectures, including our existing Electric Power Steering (EPS) platforms. They can be integrated into various vehicle models without large-scale redesign of surrounding systems.
The system supports:
High torque loads and varying vehicle weights
Vehicle- or market-specific steering calibration
Future steer-by-wire evolution
All components are developed through full vertical integration, so you get quality, consistency and scalable production for your OEM partners.
Trusted by Leading Automakers
XEPS is a proven OEM supplier in China’s fast growing electric vehicle and mobility sector, working with both emerging brands and established automotive groups. Our advanced steering systems are deployed across passenger cars, multipurpose vehicles and light off-road models.
With a strong engineering foundation and ongoing R&D investment, XEPS offers:
Custom development and DVP (Design Validation Plan) support
Full-stack steering solutions with variable control logic
Production-ready systems with rigorous quality assurance
Digitalized operations with global visibility
About XEPS
Chongqing XEPS is a leading developer and manufacturer of intelligent automotive steering systems. Specializing in high-performance steering solutions—including Variable Gear Ratio Steering—we offer complete system integration, advanced control design and scalable production for your OEM customers.
