Steer Clear of Trouble

Busted springtime roads and normal day-to-day driving eventually take their toll on steering and suspension systems. Here’s how to get back to the straight and narrow.

Steering and suspension components are, for the most part, wear components. In other words, many of the parts that comprise the steering and suspension systems wear out and must be replaced during the service life of the vehicle.

While many vehicle components have been improved to the point that their service life lasts as long as the vehicle itself (exhaust systems, for example), steering and suspension parts are different. This is not to say that the quality of these parts has not improved; it has, but the demands of everyday driving are such that some of the parts will require replacement.

Steering Problems

The rack & pinion steering system is the primary system design used on passenger vehicles today. Figure 1 shows a typical rack & pinion steering gear system. The entire system is shown, from the steering column to the mounting brackets to the outer tie rod ends. This system works very well, providing precise steering control in an efficient package design.

When the steering column is turned to steer the vehicle, the pinion gear (attached to the steering column and meshed with the rack gear) rotates and moves a horizontal rack gear. In the center of the rack gear, and on each end, is a shaft seal. Pressurized fluid is diverted to one side of the center seal or the other to aid in moving the rack gear. As you can see from Figure 1, the inner and outer tie rod ends are connected. Inside the bellows, the inner end is connected to the end of the rack gear. The result is, in effect, a long metal rod attached to each wheel. As the rack gear moves from side-to-side, the wheels turn and the vehicle is steered.

So what can cause concerns with this system? The most common problems seen are bad shaft seals on the end of the rack gear and worn outer tie rod ends.

How do you know if the shaft seals are leaking? The first clue might be increased effort due to a low level of power steering fluid. The leaking fluid will accumulate inside the bellows without necessarily leaking onto the ground. The best way to check for fluid is to squeeze the bellows and listen for a squishy sound. Better yet, simply remove the bellows and see if there is any fluid inside. If there is, the diagnosis is a no brainer. The repair, however, is expensive, as the shaft seals are not serviceable, requiring replacement of the rack & pinion steering gear.

Outer tie rod end wear is common on virtually every vehicle on the road. Some might last longer than others, but at some point in time, the outer tie rod is going to wear out. These components take the brunt of punishment from the road. Plus, the range of travel of the ball socket can be extreme as the vehicle encounters irregularities in the road surface.

Here’s how to check for tie rod wear: While you can test drive the vehicle and feel for play in the steering wheel, there are more accurate testing methods, depending on the vehicle. For most vehicles, place the vehicle on level ground. Unlock the steering column and have an assistant rotate the steering wheel from side-to-side (about 45 degrees in each direction). The outer tie rod end and the steering knuckle (see Figure 2) should move together. If you notice play between the outer end and the knuckle, the outer end is worn. Outer tie rod ends are serviceable and it is a good practice to replace these parts in pairs (both sides of the vehicle) to ensure precise steering control and even tire wear.

The testing method for outer tie rod ends on some vehicles is a bit more sophisticated. For example, the LH series service manuals (Concorde/Intrepid/Vision/LHS/New Yorker) recommend that outer tie rod end socket play be measured with a dial indicator. A U-bolt is installed on the outer end and steering arm. The bolts are equally tightened to a prescribed torque and the reading on the dial indicator is recorded. If the reading exceeds the spec, the outer end is worn. Check the appropriate service manual for the proper test method for the vehicle being serviced.

Suspension Problems

One of the most common suspension problems seen on all vehicles is bushing wear. Bushings are found in most locations where an arm or bar is connected to the frame of the vehicle. For instance, the front lower control arms, depending on design, have two pivot points where the arm is connected to the frame (the same scenario applies if the rear suspension is an independent design). This pivot point has a bushing that can wear. The failure of the rear lower bushing on the front control arm of the PT Cruiser is very common (more on that later).

Also, sway bar, or stabilizer bar, bushings are also notorious for wearing out (sway bars are found on the front and rear suspensions of many vehicles). It is not uncommon for these bushings to show signs of wear at 50,000 miles. A typical stabilizer bar installation is shown in Figure 3. In such an application, there are two bushings, or cushions, that mount the stabilizer bar to the frame and two stabilizer bar links. One end of the link is attached to the end of the bar, while the other end is usually attached to the McPherson strut. Each end has bushings.

Bad bushings are distorted and/or cracked. When this occurs, the bar is free to move within its mounts. Also, the links will not efficiently support the ends of the bar. The net result is poor stabilizer bar performance which affects the handling and stability of the front suspension.

Now, let’s take a look at that PT Cruiser bushings. The lower control arm is a stamped steel piece using rubber pivot bushings to isolate it from front suspension crossmember and frame of the vehicle (see Figure 4). The rear bushing can be serviced separately. Inspect the lower control arm for damage from contact with the ground or road debris. If there is any damage, look for distortion. Do not attempt to repair or straighten a broken or bent lower control arm (this is true of any control arm, front or rear suspension, on any vehicle).

Inspect both lower control arm isolator bushings for deterioration, which includes cracks and splits in the material. When the rear bushing goes bad, there is usually a clunking noise heard by the driver, especially when traveling over uneven road surfaces. As we mentioned, rear control arm bushing failure is quite common on the PT Cruiser.

Wheel Bearings

The last subject to cover is wheel bearings, which are found on the front and rear suspensions. The bearing is contained within the hub and bearing assembly. When the bearing fails (either front or rear), noise and vibration will result. It’s usually easy to determine if the bearing noise is from the front or back of the vehicle, but it can be difficult to determine on which side of the vehicle is the bad bearing. The noise will change as the bearing is loaded and unloaded.

Find a smooth level road surface and bring the vehicle up to a constant speed. At this point, swerve the vehicle back and forth from left to right (this will load and unload each bearing). When you swerve to the right, you unload the left bearing and vise versa. If the left bearing is bad, a swerve to the right will increase the noise level. Conversely, if you swerve to the left, a bad right bearing will make more noise. Replace the bad bearing, as required.