Rack and pinion steering can be found on just about every modern automobile. Even off-road vehicles, pickup trucks and semi-trucks use this system, as well as ATVs and UTVs. Have you ever wondered how it all works to keep you pointed in the right direction? Also, how do you know if something is wrong with your steering gear?
How Rack and Pinion Steering Works
This particular system is named after the type of gears that are used. A small pinion gear, connected to the steering wheel, meshes with a long rack gear, connected at both ends to the tie rods and steering knuckles. When the driver turns the steering wheel, it pushes the rack left or right, thereby turning the wheels left or right. Despite the mechanical advantage of this gear setup, all are power-assisted for driving ease and driver confidence.
For decades, the standard power-steering system has been hydraulically assisted. A hydraulic pump, the power-steering pump, uses engine power to generate hydraulic pressure, which is fed through the power steering hoses to the rack. When steering is in use, hydraulic pressure boosts the driver’s input force, making for easier steering.
In the past 20 years, electric power steering has become more common, appearing on many cars, particularly hybrid vehicles, electric cars and vehicles with steering-assist functions, like self-parking and lane keeping. Instead of a hydraulic pump, these use an electric motor to augment driver input.
When the Rack and Pinion Fails
There are a few ways you can tell if your steering gear is failing, such as excess noise, movement, effort or leaks.
When you’re turning the steering wheel and it seems to be looser or tighter than the rest of the rack, you could have a flat spot or notch in the steering. Wandering might be associated with this spot, usually when the wheels are pointed straight ahead. This usually indicates a worn spot in the rack teeth, which will require replacement, such as with this remanufactured power steering rack and pinion unit.
Excessive steering effort usually indicates a fault in the power booster. To remedy this, check and adjust the power-steering fluid level and check for abnormal noises in the power-steering pump. Barring pump problems, internal leaks could result in excessive effort when steering left or right.
External fluid leaks are another common problem with hydraulic rack-and-pinion steering systems. The power-assist section of the steering gear is rather small, but there are several seals that keep the fluid inside the system. Unfortunately, these seals are so inaccessible that many shops simply opt for installing a remanufactured replacement unit when treating leaks. Also, fluid leaks can lead to excessive steering effort and power-steering pump damage, greatly increasing the complexity of the repair.
Identifying Other Issues and False Flags
You may not be able to diagnose electric power-steering systems without a factory scan tool. Still, check for obvious faults, such as broken boots or electrical cables. Broken boots should be replaced as soon as possible, because water intrusion can lead to corrosion and possible short circuits.
Other issues might be falsely associated with the rack, such as loose or bent tie rod ends, loose ball joints, weak shock absorbers, broken springs or tire under-inflation. After ruling out any rack problems, check the tires, brakes and suspension for other problems ruining your ride.
Check out all the steering and suspension parts
Photo courtesy of Wikimedia Commons.
Ben has been taking things apart since he was 5, and putting them back together again since he was 8. After dabbling in DIY repairs at home and on the farm, he found his calling in the CGCC Automobile Repair program. After he held his ASE CMAT for 10 years, Ben decided he needed a change. Now, he writes on automotive topics across the web and around the world, including new automotive technology, transportation legislation, emissions, fuel economy and auto repair.