Rack & Pinion Steering Systems

The rack & pinion converts the rotational motion of the steering wheel into turning motion at the front wheels. The name refers to the 2 gears that mesh inside the rack & pinion housing. The rack gear is housed in a metal tube attached to the chassis. The ends of the rack gear are connected to tie-rods, which are attached to the steering knuckles/spindles where the wheels are mounted. The steering column shaft is connected to the pinion gear. When the steering wheel is turned, the pinion gear acts on the rack gear, forcing it to move laterally within the tube, thereby turning the front tires.

Manual rack & pinions were used on some small vehicles in the past, but today just about all vehicles have rack & pinions with power assist. In a hydraulic power rack & pinion there is a fluid-filled cylinder in the rack tube separated by a piston attached to the rack. An engine-driven pump supplies pressurized fluid to a rotary valve on the pinion gear. When the steering wheel is turned, the rotary valve directs pressurized fluid to one side of the piston, providing power assist to move the rack. When the steering wheel is turned the other way, pressure is applied to the opposite side of the piston.

Rack & pinion assemblies can suffer from several problems. The hydraulic system in power rack & pinions operate at high pressures and O-ring seals are used to contain the fluid. These seals can deteriorate from age, which results in leaks, but leaks can also originate at worn power steering hoses. If steering feels stiff and the steering wheel is hard to turn, the fluid level may be low due to a leak. Check for fluid leaks at the hoses, fittings, and at the rack tube ends. In extreme cases low fluid level and lack of lubricant can cause damage to the rack & pinion gears and you may hear grinding noises. A torn rack & pinion bellows, also known as a boot, can allow dirt and debris to get into the rack and destroy the seal, and also prematurely wear the inner tie-rod joint.

When driving on a straight road, if there’s a lot of play in the steering wheel when it’s centered, and the car doesn’t begin to turn until the wheel is moved quite a bit, then the pinion and rack gears are most likely worn, which requires rack & pinion assembly replacement. Worn gears can also cause wandering and loose steering. Wander can also be caused by worn steering mount bushings, which can allow the whole rack assembly to move back and forth. Check the bushings for cracks, splits, disintegration and excessive movement. If the vehicle is properly aligned but wants to pull to one side while driving on a straight, flat road, the rotary valve may be leaking and allowing fluid to pressurize one side of the rack piston. This would also require rack & pinion assembly replacement.

No matter what your repair or upgrade needs are or what you’re working on, we have the rack & pinion assemblies and related components to restore safe, predictable, and easy steering system operation. We offer manual rack & pinion assemblies and both hydraulic and electric power rack & pinion assemblies. They’re manufactured to original equipment specifications and most come with bellows and tie-rods installed for a complete repair. We also have complete seal kits, bearing kits and repair kits if you want to tackle overhauling the rack & pinion assembly yourself. Our bellows/boots kits can help you make timely repairs that can prevent expensive damage, and you can take care of rack & pinion mount related handling, alignment, and tire wear problems with our replacement mount and bushing kits.