Volvo Rack And Pinion Complete Unit
Rack and Pinion steering systems have been used for many years now. They were first seen on imported vehicles, but are now commonly used by American car manufacturers. Steering Rack and Pinion systems are used on virtually all front wheel drive vehicles as well as many All Wheel Drive and 4 Wheel Drive vehicles. A Rack and Pinion is a system that takes motion such as a rotating gear (the pinion) that is moving in a circular motion and converts the movement to a linear motion (the rack).
The old style system that was used on cars for many years was called an Integral system. This system used a pump, a gear box and steering linkage. Inside the gear box was rotary valves, check valves and other components that could all fail. A hydro-boost system incorporated the brake system into the steering system and used hydraulic pressure from the steering pump instead of a vacuum booster. The other type of system, rarely seen, uses a control valve and power cylinder to move the steering linkage.
Steering Rack and Pinion Work together as a unit
A steering rack and pinion system is a much simpler system in many ways. When turning the wheel, the steering shaft turns the pinion and moves the rack back and forth. This in turn moves the tie rods and then the wheels turn. There are inner and outer tie rods on all vehicles with Rack and Pinion steering. The inner tie rods are what actually connect to the inner workings of the rack and pinion. They are normally serviced with the rack and pinion assembly, as they are attached to the rack itself. The outer tie rods connect the inner tie rods to the wheels. They are normally connected with an adjusting sleeve, which is also used to align the vehicle.
Steering Rack and Pinion systems are rarely used without some type of power assist unit on passenger vehicles. The exception to this would be muscle car racing conversions, such as older Ford Mustangs, Chevrolet Camaros and vehicles like them. The power assist could be one of several different types. Hydraulic power steering would be the one most people are familiar with. This system uses a mechanical power steering pump, usually driven by a belt, to build hydraulic pressure to assist the driver in turning the wheel. Electro-hydraulic assist power steering also uses hydraulic pressure to assist the driver, but the pump is electrical rather than mechanical. This is beneficial as there is no horsepower loss due to turning a pump. The last type of power steering assistance is electric power steering. This is the most advanced in the market today. This system uses no hydraulic fluid pressure to assist with steering. Instead, electric assist uses a module to determine how much power should be delivered to assist with steering based on many factors, such as speed, how fast the wheel was turned and even whether you are moving forward or in reverse.
Sometimes, you will be asked what the steering ratio is when ordering a rack and pinion, or more often, what is the lock to lock. Steering ratio is the relationship of how many degrees the wheels turn in relationship to how far the steering wheel turns. For example, if the steering wheel is turned one complete rotation (360 degrees) and that makes the wheels turn 30 degrees, the ratio is 360/30 or 12:1.
Higher ratios make it easier to turn the wheel, as you need to turn the steering wheel more to move the wheels. Lower ratios are normally found on high performance vehicles. Lock to lock refers to how many turns of the steering wheel it takes to go from full left to full right. For example, if the wheels are turned fully to the left, you count how many turns of the steering wheel it takes to have the wheels turned fully right. If you turned the steering wheel 3 1/2 times, you would say you have 3.5 lock to lock.
Variable ratio steering on rack and pinion steering is accomplished by having more teeth in the center of the rack and less on the ends. This makes it easier to drive, as when you are moving straight at highway speeds, you will not over correct as you try to keep the vehicle moving straight. More teeth on the rack means you need to move the steering wheel more to turn. The smaller amount of teeth on the ends make the wheels move more when fully turned, making it easier to perform maneuvers such as parking.
Fixing Rack and Pinion is an Easy Task
A steering rack and pinion may need to be replaced for several reasons. You may notice that power steering fluid needs to be added, which is a sign the seals may be leaking. You may not see this right away as there are boots at the ends of the rack and the fluid may be going there. Another problem is the bearing where the steering shaft attaches often goes badly. This would cause a noise as well as a scraping sensation when you turn. Racks often make bumping or thumping noises when the internal parts are worn, or the mounts have simply come loose. The most common signs the rack has gone bad are the steering will be stiff when cold, it will be harder to steer than normal and the wheel will not return to center by itself. If any of the above conditions exist, the rack should be replaced. From my own experience, rebuilding the rack with simple seals and bearings is usually just a short term fix and the rack and pinion will soon need to be replaced. This is probably due to normal wear and the buildup of worn parts that cannot be cleaned without taking the whole unit apart and rebuilt. There are approximately 45 individual components in the average power steering rack and pinion. Valves, seals, the rack tube housing, the pinion housing, lines, bellows which would all need to be cleaned to properly rebuild the unit.
Replacement Procedure of Rack and Pinion
The most common way to purchase a rack and pinion is as a re-manufactured unit. There is actually extremely limited availability for new rack and pinions. Companies such as A1 Cardone, Arc, ZF, A/C Delco, TRW are all suppliers of re-manufactured units. Some of them are even the original OEM suppliers.
When you finally decide to replace the power steering rack and pinion, on most applications, you will only need a few simple tools. A few wrenches, a ratchet and a few different size sockets. The hardest part will be raising the vehicle enough to do the job. You will need to loosen the lug nuts, jack up the vehicle and set in on stands, and then you will need to remove the wheels. The tie rods need to be removed from the steering knuckles. Remove the power steering lines. Remember to have some absorbent rags to catch any fluid. There are usually 2 clamps holding the rack onto the firewall. After you remove these clamps, the rack will come out. After removing, count the number of turns to remove the outer tie rods. Install them onto the replacement rack turning them the same number of turns. This will make the vehicle drivable until you can get a proper alignment done. Reinstall reversing the procedure, being sure all lines are tight. Refill the power steering and recheck after running the vehicle. Best Deals on Volvo,Cadillac,Chevrolet,Nissan,Jaguar,Porsche,Pontiac Rack and Pinion Complete Units only on TheAutoPartsShop. Get The Lowest prices ,Free Shipping & Free 2 Year Warranty on Volvo Rack and Pinion. http://www.theautopartsshop.com/parts/rack-and-pinion-complete-unit.html#