SRT-4 L4-2.4L Turbo VIN S (2004)
Steering Gear: Description and Operation
DESCRIPTION - POWER STEERING GEAR
The power steering gear is mounted on the front suspension crossmember (Fig. 1). The outer ends of the outer tie rods attach to the steering knuckles.
There are two different type power steering gears used on this vehicle, a standard, and an optional which is used on the R/T and SRT-4 vehicles.
Externally the gears appear the same. Internally, the standard has a 16:1 turning ratio while the R/T / SRT-4 gear has an 18:1 turning ratio. The gear
used on R/T and SRT-4 vehicles also has a restricted lateral (lock-to-lock) travel range to accommodate the wheel and tire combinations. Sport feel
valve coding provides R/T and SRT-4 vehicles with more firm feel steering to match the performance tire compounding and construction.
NOTE: The power steering gear should not be serviced or adjusted. If a malfunction or oil leak occurs with the steering gear, the complete steering
gear needs to be replaced.
OPERATION - POWER STEERING GEAR
Turning of the steering wheel is converted into lateral (side-to side) travel through the meshing of the helical pinion teeth with the rack teeth located in
the steering gear. This lateral travel pushes and pulls the tie rods to change the direction of the vehicle's front wheels.
Power assist is provided by a pump and is controlled by an open-center, rotary type control valve. It directs fluid to either side of the gear's integral
steering rack piston. Depending on the rotation of the steering wheel, more fluid pressure is directed to one side of the rack piston compared to the
other.
Road feel is controlled by the diameter of a torsion bar which initially steers the vehicle. As steering effort increases, as in a turn, the torsion bar twists
causing relative rotary motion between the rotary valve body and valve spool. This movement restricts fluid flow to one side of the integral rack piston
and redirects fluid behind the other side of the integral rack piston, building up hydraulic pressure, thus assisting in the turning effort.
