IZOD IndyCar® Series Use of the Variable Ratio Steering Rack

Use of the Variable Ratio Steering Rack

In 2008, the IndyCar Series moved from a standard (or consistent) steering rack to a variable-ratio steering rack for road/street course events. Differentiations are minor.
A standard steering rack is a metal bar with a series of evenly spaced teeth that links to the front wheels of the car. A pinion controlled by the driver turning the steering wheel catches on the teeth of the steering rack, causing the wheels to turn in the corresponding direction based on the load and movement of the driver.
The variable-ratio steering rack mechanism is similar, but the pitch of the teeth on the steering rack change. Also, the teeth are not spaced evenly; they are closer together toward both ends of the steering rack. The pinion is also a different shape. These slight changes allow the pinion to catch on the teeth easier to turn the wheels, diminishing the amount of effort needed by the driver to turn the steering wheel.

“With our high-downforce cars, the steering load is significantly stronger on road courses and street circuits than ovals,” said Les Mactaggart, senior technical director, IndyCar Series. “We decided to move to the option of the Variable Ratio Steering system to benefit all drivers by reducing the amount of effort used to turn at these physically demanding tracks.”

FACT:
The transition to the Variable Ratio Steering system began in 2007, when several
drivers tested the device during IndyCar Series road and street events. More
testing took place during 2007 post-season testing to fine tune the product.

FACT:
The decision to move away from a standard steering rack was made because of
the growing number of road and street events being added to the IndyCar Series
schedule. It is optional in all IndyCar Series cars.

FACT:
The new steering system does not provide an advantage for the smaller drivers; It
assists all drivers equally by providing an easier steering load during
physically demanding road/street events.

FACT:
Sanctioning bodies such as Grand-Am and Formula One (optional) also use a
Variable Ratio Steering system.

More Information regarding the IZOD IndyCar® Series can be found at: www.indycar.com

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