A vehicle’s suspension has a very important job, yet many times it’s overlooked. Most of the work that comes to my shop is drivability work, and this makes the problem of missing steering/suspension work even worse, because I tend to get lazy and want to concentrate only on the drivability side of the business. When I stop and think about different systems on a vehicle, though, I realize that the brake system is the most important (since the brakes are the only way of getting the thing to stop) with the steering and suspension system running a very close second. Problems in these systems can cause a vehicle to become very unsafe to operate on the public roads.
Rust from a worn ball joint. As road salt intrudes a suspension part, the grease is displaced with the salt brine. This causes the parts to rust from the inside. Watching for the brown rust around the ball joint boots is an easy way to spot trouble.
Thinking about a vehicle steering/suspension system, we must start where the tires contact the road. If this tire–to-road contact is not correct, then the ride quality suffers and the vehicle is hard to control. The tires are a very important part in the suspension system, needed to absorb road shock and soften the vehicle ride.
Just as important are the parts used to keep the tires located in place while allowing them to move and steer the vehicle. Ball joints, tie-rod ends, shock absorbers, struts, springs and a few other things work together not only to soften the ride but also to keep the front and rear suspension tracking straight and true under the car. Don’t forget about the rear of the car. It also is a very important part of the steering/suspension system, because the rear wheels must run straight and true or the vehicle will not handle properly and fuel economy will suffer.
While we are talking about suspension, we should not forget about the importance of the shock absorbers. Their job is to not only smooth the bounce from the vehicle and make the ride comfortable for the occupants, but they also have a very important role in keeping the tires in proper contact with the road surface. Shock absorbers that are not doing their job will let the tires bounce from the road surface. When this happens, the tires will wear rapidly, and the vehicle can become very difficult to control, especially at higher road speeds and on crooked roads with rough pavement.
Sway bar connector links. Sway bar bushings and connector links are a great place for rattles to occur. Use a pry-bar to move the sway bar up and down and look for any movement in the bushings. Watch closely for worn bushings in the connector links.
Every time a vehicle is in for any sort of service, a quick suspension check is should be performed. The inspection starts as the technician is walking through the parking lot on his or her way to bring the vehicle to the bay. From a distance, it is easy to see worn tires and front wheels that do not stand straight. Many times, squeaks can be heard while the car is rocked as you open the door and sit down in the driver’s seat. Listen for squeaks as you turn the steering wheel. Vehicles that are driven in salt brine will get salt water in both the ball joints and tie rod ends. This forms rust in places that eyes cannot see, and rusty ball joints or tie rod ends can emit some strange noises as they are being flexed. Before you start to move the vehicle, turn the steering wheel from the left lock to the right lock and back a few times. Many times binding steering or weak power steering pumps can be found this way if the steering wheel is gently turned while the engine is at an idle. A quick test drive over some uneven pavement is also a great way to see if the shock absorbers are doing their job.
Caked grease on grease fittings is a great way to shorten the life of the suspension component. Always remove the dirt and dried grease from the grease fittings to keep the dirt out of the component being lubricated
Before the vehicle is lifted on the hoist, have someone gently rock the steering wheel side to side while you watch the tie rod ends and idlers for any unwanted movement. Once the vehicle is on the hoist it is easy to do a thorough visual inspection. From under the vehicle, it is easy to see if any of the shock absorbers are dented, leaking or lose. How about the boots around the ball joints and tie rod ends, are any of those cracked or broken? How about the sway bar mounts and connecting links? Worn bushings and loose or missing parts can cause rattles and poor handling.
When lubricating suspension joints, always wipe the dirt and grease from the grease fitting. You do lubricate the fittings, don’t you? If this grit and grease is left on the grease fitting, dirt will be forced into the suspension joint, which will reduce the useful life of the joint. This debris can also clog the grease fitting, making it nearly impossible to lube the joint at all.
Tire inspections are also a great way to detect suspension and alignment problems. By running your hands over the tires, a technician can feel for things like tire cupping, feather edges on the tire tread, along with lumps and hot spots on the tires. All of these things are indicators of either tire problems or alignment problems that are hiding where we can’t see them with our eyes.
Front tire mismatch. All four tires are the same brand, the same model, but the right front was a different sub model. The tread pattern on the two front tires are close, but different. There is a complaint of a slight pull to the right. Examining both front tires found the inner tread of each tire is wearing faster than the center of the tire. There is also a slight feather edge running across the inner tread band of each tire giving the indication of a camber problem.
Become a Tire Whisperer
Reading the tire wear with your hands will tell the technician a lot about the vehicle alignment. As long as the tires are running down the road straight and the tire load is evenly distributed across the tire, the tire tread will feel smooth to the touch. If the tire is being pushed sideways down the road (misaligned toe angle), the tire tread with have a feather edge along either the inside or the outside edges of each of the tire treads. Feeling the inside and outside tread ribs might illustrate feather edges that run crosswise of the tire. Most times this wear pattern will be caused by a camber angle that is incorrectly adjusted. In this case, the tire-rotating axis is not parallel with the road, and the inside of the tire is being pushed down the road while the center of the tire is rolling nice and smooth.
This always calls for more system analysis. Depending on the type of suspension, the cause could be sagging springs, worn ball joints, or something being bent in the suspension system or all of the above. Most of these kinds of problems can be easily found without the need of an alignment machine.
Adjusting the alignment with worn parts does not fix the real problem; it will only cover up the existing problem. Some in-depth inspection is in order at this point.
Dealing With a Clunk
This nice looking 2006 GMC crew cab truck has a complaint of a light clunk in the front suspension when turning corners to the left. On the test drive, we noticed a slight pull to the right, felt the shock absorbers were doing a good job of preventing vehicle sway and smoothing out the bumps in the road and heard a very slight clunk noise when making a left turn while hitting a slight bump in the pavement. Back in the shop, a fellow tech rocked the steering wheel left and right while I watched for any sideways movement in the tie rod ends but none was found. We raised the vehicle on a hoist and inspected the front and rear suspensions. We found no problems with the front sway bar system, and all brake calipers are fastened properly.
Pressing a lower ball joint into the lower control arm.
An inspection of the shock absorbers did not show anything loose or leaking. We inspected the front tires and found a slight feather edge on the inner tire tread ring. This wear pattern points to a camber problem, which worn lower ball joints can cause. The front tires also have a different tread pattern, and although both tires are the same manufacturer and make, the model of tire is different. Shaking the front wheels found no noticeable movement in the tie rod ends or the idler arms but more inspection is needed, since just shaking the front wheels will not find ball joints that are worn beyond their wear limit. We’ll need to unload them first before we can measure their play and see if they are getting to an unsafe condition. To do that on this vehicle design (verified by looking up the inspection procedure in our service information system), a floor jack was placed under each lower control arm and a dial indicator was used to measure the wear on the lower ball joints. By comparing this measurement with the ball joint specifications found in service information, I found that both lower ball joints were worn more than .020” over the wear limit.
Always pay attention to the installation instruction supplied with the part. The little hole in the rim of the ball joint is very important.
Compiling the test data brought me to the conclusion that the excessive wear in the lower ball joints is the reason for both the “clunk” when turning and the feather edging on the inside of the front tires. The mismatch of the two front tires is the reason for the slight pull to the right when driving. This light truck will need to have the upper and lower ball joints replaced in the front suspension. Once the repair is made, we’ll have the alignment checked and brought into spec if needed.
The GMC light truck had a set of new ball joints installed on both sides of the front suspension. When installing new parts, be sure and read the instruction papers that are supplied with them. In this case; the little hole in the rim of the top ball joint needs to be put in the correct place.. While the tires were off, the tires were rotated front to back, all tires properly inflated, and then the alignment adjusted. On the “after the repair” road test, the slight pull to the right was gone, the “clunk” when turning was gone and the vehicle once again drives straight and true.
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