GM Service Manual Online
For 1990-2009 cars only

The power steering gear is serviced and replaced as a unit.

The steering gear is mounted on the left lower side frame rail and is secured by four bolts. The steering gear is joined to the intermediate shaft by a coupling that helps isolate noise and road shock from the interior.

The major internal components of the steering gear are the valve, worm gear, rack, and the pitman shaft. The movement of these parts, while turning or parked, is aided by hydraulic pressure supplied by the pump. Manual steering is always available at times when the engine is not running or in the event of pump or belt failure. Steering effort is increased greatly under such conditions.

The stub shaft, valve, worm gear and rack are all in house. The steering gear has a recirculating ball system which acts as a rolling thread between the worm gear and the rack. The worm gear is supported by a worm gear thrust bearing preload and two conical worm gear thrust bearing races at the lower end, and stub shaft bearing in the stub shaft adjuster at the upper end. When the worm gear is turned right, the rack moves up in gear. Turning the worm gear left moves the rack down in gear. The rack teeth mesh with the sector, which is part of the pitman shaft. Turning the worm gear turns the pitman shaft, which turns the wheels through the linkage. The control valve in the steering gear directs the fluid to either side of the rack. The rack converts the hydraulic pressure into a mechanical force.