Continued from Part 1

DIAGNOSING STEERING AND SUSPENSION TIPS & TRICKS

WARNING: Note that servicing, repairing, or replacing suspension and steering components require equipment and a degree of skill/mechanical aptitude that novice DIY mechanics generally do not possess. For this reason, it is recommended that all suspension and steering system repairs be left to professional technicians, or at least, to non-professional mechanics that have some experience of working on these systems.

Almost all steering and suspension components fall into the “[these are] life and limb parts” category, which makes it vitally important to address all and any issues with these systems without delay, or preferably, immediately when problems such as imprecise steering, uneven tire wear, poor steering response, or difficulty with maintaining directional control arise.

Bear in mind that many, if not most steering and suspension parts are not easily accessible, and often remain ignored or overlooked during routing servicing or maintenance procedures. Long experience in the auto repair trade has shown that car owners are often unaware of defective, damaged, or broken steering and/or suspension components on their vehicles. In many cases, these defects are discovered accidentally, or worse, only after a crash that was caused by a defective steering /suspension system component had already occurred.

Nonetheless, steering and suspensions systems usually do not fall apart or fail catastrophically without giving at least some advance warning. If these warning signs are heeded, major issues can generally be avoided, simply by repairing, or replacing components as the wear out, Failing to do this in a timely manner usually turns relatively small routine maintenance chores into major repair efforts (and hefty repair bills), since all steering and suspension components have a direct effect on all other parts and components in these systems.

If you have issues with uneven tire wear, a vehicle that pulls to one side or a generally “sloppy feel” to the steering on your vehicle, work your way through this quick guide to steering issues to help you identify the problem. Here is what to look out for when-

TIRES WEAR UNEVENLY

Tires that show accelerated wear either on the inside or outside shoulders is a sure sign of poor wheel alignment, which can have several causes such as-

• Worn tie-rod ends

Worn tie-rod ends usually causes the vehicle to “wander” across the road, since the angle between the two front wheels change constantly, with the degree of “wander” largely depending on the amount by which the angle between the wheels change. The vehicle may also pull to one constantly, or sometimes, only when the brakes are applied.

• Worn ball joints

On applications that use Macpherson struts, the bottom of the strut is connected to a control arm with a ball joint. In this arrangement, the control arm forms one side of the triangle that represents the suspension “cradle”, with the other two sides being the strut, and the vehicle itself, respectively. In practice, the ball joint both allows the suspension to move up and down, and the steering knuckle to pivot, which allows the front wheels to deviate from the straight ahead position in response to steering inputs.

If the ball joint wears out, the wheel loses its camber setting, which is a setting that deviates slightly from the dead upright position. Camber is one of the settings that influence straight-line tracking, and hence, directional stability. Worn ball joints usually (but not always) result in tires wearing rapidly on the inside shoulder.

Incorrect camber usually causes poor steering response, an imprecise “feel” to the steering, or in some cases, a constant pull to one side, especially when the ball joint on only one side is worn.

• Worn Macpherson strut mountings

Macpherson struts are connected to the vehicle frame with a flexible, resilient rubber mounting that incorporates a bearing to allow the strut to pivot in response to steering inputs. Over time, these mounting can lose some or all of their ability to hold the top of the strut in position, which results in a loose, sloppy feeling to the steering. Other symptoms could include a reduced straight-line tracking ability, and severe knocking or thudding sounds when the vehicle travels or uneven road surfaces.

• Worn control arm bushings

Control arms are connected to the vehicle frame with resilient, flexible bushings that allow the control arm to move up and down along with other suspension components in response to bumps in the road surface. Over time, these bushings can lose some, or all of their ability to control the lateral movement f the control arm, which usually results in poor steering response, poor wheel alignment, and accelerated tire wear, and even reduced braking performance on some applications.

Note that the suspension systems on some applications (particularly pickup trucks), have two “A”-shaped control arms on a side that are each connected to the vehicle frame with two bushings, but also to each other via the steering knuckle with two ball joints. One ball joint connects to the top, and one at the bottom of the steering knuckle, with the whole forming a moveable structure that allows up and down movement, as well as a means for the steering knuckle to pivot, via the two ball joints.

Excessive free play in one or more bushings and/or ball joints on double control arm suspension systems can cause poor steering response, poor wheel alignment, accelerated tire wear, and in some cases, reduced braking performance.

• Worn steering rack

Almost all light vehicles use rack-and pinion steering systems that consist of a straight bar (the rack) with teeth cut into them that engage with teeth cut into the pinion, which is connected to the steering wheel. As the steering wheel is turned, the teeth on the pinion move the rack, thus creating the steering action.

While there is not much that can go wrong with the teeth on the rack or the pinion, the rack slides through two tough, but wearable, bushings in the ends of the tube that houses the rack. When these bushings wear out, the rack is no longer held firmly in position, with the result that some of the turning moment from the steering wheel is taken up by the excessive clearance between the rack and the bushes. In practice, this causes a loose, sloppy feel to the steering, and maintaining directional control can become difficult at high speeds.

• Worn draglink components

Applications that use double control arm suspension systems usually do not use rack-and-pin steering mechanisms; instead, these applications use a steering box that acts on only one front wheel. The steering action is transferred to the other wheel with a bar known as a “drag link”, which, while it is attached to both steering knuckles, is further supported by one or more idler arms that are attached to the vehicle chassis.

Thus, when the steering wheel is turned, the steering action is transferred to the other wheel, and in a fully functional steering system, both wheels will pivot by the same amount. However, draglinks typically have many pivot points that can wear out, which means that depending on which points are worn out, the front wheels may not turn by the same amount when the steering wheel is turned.

Typically, worn draglinks cause a delay in steering action, poor steering response, reduced, or poor straight-line tracking, and reduced braking performance. In some cases, the vehicle may wander across the road so severely that maintaining directional control becomes difficult, if not impossible at high speeds.

HOW TO DIAGNOSE EXCESSIVE FREE PLAY IN STEERING SYSTEMS

While all of the above should provide most non-professional mechanics with some background information on why steering systems sometimes develop a sloppy feel, actually finding a defective component, and worse, determining whether free play in that components is excessive or not, can be a tricky affair.

However, while there are ways of detecting defective components definitively, the best way of doing it requires that the vehicle be on its wheels, with its full weight acting on the suspension and steering systems. Lifting the vehicle off the ground extends the suspension, which can have the effect of removing free play between components since the various parts of the suspension, and often the steering system as well, are now locked or wedged against each other, which makes relative movement between components almost impossible. Therefore, here is what to do-

Place the vehicle on a four-post vehicle hoist

Hoists of this type have two platforms on which the vehicle can rest on its wheels while it is being lifted off the ground. Of course, few non-professional mechanics have access to this type of vehicle but assuming that readers of this post have access to a suitable hoist, place an assistant in the vehicle, and hoist it to a height that is comfortable for you when you are under the vehicle.

NOTE: Make sure to engage the parking brake while the vehicle is on the hoist to prevent it rolling off.

Make sure you have a powerful flashlight or other light source available, and perform a thorough visual inspection of all visible suspension and steering system components from underneath the vehicle. Look for obviously damaged or broken components, but bear in mind that damage to some components will not always be apparent or visible.

Next, have the assistant in the vehicle turn the steering wheel rapidly from side to side, but only until a resistance is felt; this usually requires less than a quarter of one revolution of the steering wheel in either direction. Note that on applications with power steering, starting the engine may be required to achieve the desired effect.

Moving the steering wheel in this manner will reveal-

• Free play in tie rod ends
• Free play in the steering rack
• Free play in drag link pivot points, idler arms, and sometimes in control arm bushings

Instead of moving in the direction that is dictated by the design of the steering system when the steering wheel is moved, parts may move up, down, sideways, or in other ways that clearly demonstrate movement relative to each other. Ideally, steering system components should only rotate around each other, and any movement away from each other indicates that the components are worn.

Next, obtain a 24-inch crow bar (aka pry bar) with a flattened point, and insert it between the bottom of the control arms and the ball joints, but take great care not to damage the wheel speed sensors and their wiring, brake lines, and other parts and components. The object of this test is to attempt to pry the various components being checked away from each other; if excessive free play is present, it will become apparent as movement relative to each other. Ideally, ball joints should only allow rotation; any other movement indicates that the part is worn. Using firm pressure, test all the ball joints by attempting to pry them away from the control arm or steering knuckles.

Test the control arm bushings in the same way. Insert the pry bar into a point between the control arm and the frame of the vehicle as close to the bushing as possible, and apply a levering force to gauge the resilience of the bushing. However, note that while there must be some movement (since the bushing is designed to be resilient), there should be no free movement in any direction. All movement must be against a firm resistance; if there is no resistance or if you hear a clunking noise when you apply a levering force the bushing are worn, damaged, or broken, and likely the cause of the sloppy feel to the steering.

ONE MORE THING…

Bear in mind that all of the issues, problems, defects, and faults described above can produce uneven or accelerated tire wear, since the alignment angle between the front wheels are directly impacted when almost any steering or suspension system component wears out, breaks, or becomes unserviceable for whatever reason.

Note also that stripping down and reassembling the steering and suspension systems for the purposes of making repairs can (and almost always does) destroys the original wheel alignment settings. Therefore, it is critically important to have a proper wheel alignment check performed by competent technicians whenever repairs have been made to the steering or suspension systems.