Much of the efficiency of modern suspension systems, and by extension, the handling characteristics of modern vehicles depends on how well the steering rack performs. Steering racks are also safety critical components, and although they are not usually prone to sudden or catastrophic failure, steering racks do wear out over time and need to be replaced when they do in order for the vehicle to be operated safely. Within this article, we discuss how a steering rack works, the common symptoms of a bad steering rack, a high level overview of the replacement procedure to give you an idea of project involvement, and provide our recommendations for the best steering rack brands.
Function Of A Steering Rack
A steering rack is a geared mechanism that makes it possible to steer the wheels of a vehicle when a driver provides input using the steering wheel. In terms of operation, a steering rack consists of a tube that encloses a geared rack (a row of teeth on a straight surface) that engages with a pinion gear that is connected to the steering wheel via a shaft. These teeth on these gears typically have a helical cut, which allows multiple teeth on the pinion to contact the teeth on the rack simultaneously, which both eliminates backlash (free play) between the gear teeth and increases precision in steering control. As multiple gear teeth are in contact at the same time, the teeth share the load, thereby limiting wear.
Attached to the ends of the geared rack are components called tie-rod ends, which are attached to the steering knuckles or wheel hubs. Thus, by turning the steering wheel, the teeth on the pinion gear cause the rack to move in the direction of the steering input, and this movement is then transmitted to the front wheels via the tie-rod ends.
In cases where the steering is power assisted, the tube that encloses the rack serves as a hydraulic cylinder and the rack also functions as a piston; in these designs, pressurized fluid is fed to the steering rack via hoses that deliver fluid from the power steering pump. Thus, if the steering wheel is moved, pressurized fluid acts also on the rack, thereby reducing the steering effort required to move the rack, which is a useful feature to have during low-speed maneuvers such as parking. Most modern cars incorporate this technology.
Note though that on modern power steering systems, the power assist component is usually designed to progressively fade away with increasing road speed, and is usually completely inactive beyond a specified road speed in order to provide the driver with improved steering feedback.
Common Symptoms Of A Faulty Steering Rack
Symptoms of defective steering racks are largely similar on most vehicles, and may include the following:
Since the moveable rack is supported by bushings, these bushings can wear out over time. When this happens, shock and vibration from the wheels are transmitted to the steering rack which can cause rattling, thumping, or knocking noises when the rack vibrates against the worn bushings. In some cases, some of the wear in the bushings can be adjusted out with an adjusting mechanism that is built into the steering rack.
This is common on fluid driven power steering systems, and is usually the result of the failure of the seals that seal the power steering fluid inside the steering rack. Note though that replacing leaking seals seldom provides more than a temporary solution.
Excessive Steering Play
Excessive free play in steering racks can occur when the rack and pinion gear teeth are so worn that they no longer engage properly when the steering wheel is turned. Note that this issue is more common on vehicles that are driven predominantly on straight roads with few turns for the majority of their lifespans. This occurs because most of the wear on the gear teeth is localized to one small area, as opposed to distributed over more teeth as would be the case for vehicles that spend more time being driven on twisty roads.
Replacing A Steering Rack
It should be noted that replacing a steering rack on a modern vehicle is relatively involved, requires quite a few tools, and can possibly require removal of the engine or front suspension depending on vehicle type. Further, there is potentially fluid under high pressure which can be dangerous if unaccounted for, so we strongly recommend consulting a factory service manual prior to starting work to make sure you are aware of all safety considerations and take all necessary precautions.
Note: The example steps below are intended for general informational purposes solely to help give you an idea of project difficulty and tools required. As all cars are engineered differently, repair procedures and safety hazards vary from vehicle to vehicle. To ensure that you have a vehicle specific repair procedure and an exhaustive list of potential safety hazards, we advise you reference a factory service manual for your vehicle. Similarly, referencing a repair manual such as Chilton or Haynes might serve as a less expensive alternative.
Step 1 – Assuming that the steering rack can be removed without having to remove the engine and/or front suspension, loosen the lug bolts using a lug wrench on the front wheels but don’t remove the bolts entirely as they still need to support the vehicle for the time being. Next, lift the vehicle off the ground using a properly rated floor jack and support it with properly rated jack stands. Observe all safety measures during this step, and ensure that the vehicle is stable on the jack stands before proceeding.
Step 2 – Remove the lug bolts entirely from the front wheels, remove the wheels, and place them safely out of the way. Detach the tie-rods from the wheel hubs using a ball joint separator. Place all fasteners in one spot to avoid losing any (a magnetic tray may help you in this respect).
Step 3 – Locate the brackets fastening the steering rack to the chassis or suspension, and loosen the retaining bolts, but do not remove them completely at this point, since you may need to wiggle the rack around during the next step. A socket set and a set of combination wrenches will likely do the job, but since access can be tight, a good set of ratcheting wrenches can potentially save a lot of time here.
Step 4 – Locate the steering shaft attachment point, and remove the bolt that locks the steering shaft to the pinion gear. Note that this can be challenging, so use your best judgement during this step to prevent damaging unrelated parts and components.
Step 5 – If the steering rack is power assisted, use flare nut wrenches to remove the high-pressure line first (after observing safety precautions associated with pressurized fluid), but be sure to catch any escaping fluid in a suitable drain container for easy disposal after the job is complete. Remove the low-pressure line, but remember that the power steering reservoir usually will drain through this connection, so be ready to catch a large quantity of fluid.
Step 6 – Remove the brackets and bolts holding the steering rack, and extract the rack from the vehicle. Note that this can be very geometrically difficult due to limited space, and in some cases, can require some creative thinking. Another thing to consider is that often times you can get a steering rack that comes with new tie rods already fitted, which saves time since this makes the process of replacing a steering rack a bit easier.
Step 7 – Reinstall all parts in the reverse order of removal, and make sure all fasteners are torqued to their manufacturer specified values using a calibrated torque wrench. Pay particular attention to the pinion/steering shaft locking bolt; this is a safety critical part so we recommend following the procedure in the factory service manual since it can differ slightly from vehicle to vehicle. When installing, ensure that the steering in on center before connecting the steering shaft to the rack to minimise calibration faults in the steering angle sensor.
If the rack is power assisted, remove the plastic plugs that protect the hydraulic line attachment points ONLY when you are ready to attach these lines. Premature removal of the plugs could allow dirt or grime to enter the rack which can reduce its lifespan.
Step 8 – Once the steering shaft is connected securely to the rack, attach the tie-rod ends to the wheel hubs, making sure all fasteners are torqued to their specified values.
Step 9 – Fit the wheels, lower the vehicle to the ground, properly torque the lug bolts, and refill the power steering reservoir before starting the engine or turning the steering wheel. When the reservoir is filled up to the indicated mark, start the engine, and allow the fluid to circulate through the system while turning the steering in opposite directions. Monitor the fluid level during this step and keep it topped off. Fill up to the ”FULL” mark on the reservoir once the fluid level stabilizes. Considering the safety critical nature of the steering system, double check that everything has been reassembled properly per manufacturer specification and troubleshoot as necessary.
Step 10 – You will likely need a wheel alignment and the steering angle sensor recalibrated, but note that these steps should only be performed by a suitably qualified mechanic to ensure that all safety systems will work as they should.
Best Steering Rack Brands
When it comes to choosing a steering rack, there are many options available for most vehicles. In order to save you some time, we have shared a list of our favorites.
Ac Delco is well recognized as an industry leader in the manufacture of steering racks for American vehicles, particularly GM and related brands. They are quite widely used, and therefore are readily available and relatively easy on the wallet. Overall, quality is good and price is fair, making them a solid choice for your next steering rack replacement. As such, we think you’ll be satisfied if you decide to give them a try.
Click here to find an AC Delco steering rack for your vehicle.
A1 Cardone is a widely known player in the automotive industry that supplies everything from brake components to suspension parts to steering racks. They are widely used by the DIY mechanic crowd owing to their high quality and reasonable cost. They cover a wide variety of vehicle manufacturers, so unless you have a super niche application, A1 Cardone will likely have you covered. We are confident that you will be very satisfied if you opt to use one of their steering racks for your next repair.
Click here to find an A1 Cardone steering rack for your vehicle.