Inspecting Suspension Components
Story and Photos By: Mark Yanochko
A great deal of automotive technology has been revised, redesigned and improved over the last 35 years. As a result, the car runs better and the parts last longer. Some parts, such as a stainless-steel exhaust system, can outlive the life of the car. For the most part, rust is no longer an issue, regardless of where you live. And, whoever thought spark plugs could last 75,000 miles?
But, some parts still wear out and must be replaced, even if the service life intervals are longer. Among those parts included in this group are suspension components—ball joints, struts, shock absorbers, coil springs and bushings. In this How To article, we’re going to review the inspection procedures for suspension components, front and rear.
FRONT SUSPENSION
The first components to check on the front suspension are the springs and struts. If you’re performing this inspection in your garage, you’ll need to jack up the front end and remove the wheels. Look at each end of the spring to see if the pigtail is broken. If the car has a lot of miles on the odometer (more than 100,000), you might want to check the vehicle height. If it is below spec, the springs are probably worn and should be replaced.
Check the strut for leaks. Push up the boot, A, that covers the rod, B, shown in Figure 1. Look for any fluid that may have leaked out of the cylinder. If any is found, the strut needs to be replaced. Put the wheels back on the car and lower the vehicle. Do the rebound test by pushing down on each corner. The car should dampen on one rebound. If there is more than one rebound, the strut should be replaced (this test can also be done on the rear of car).
Remember, strut replacement is a difficult job. It can be done by the DIYer, but a special tool is required to compress the coil spring. You should also have a service manual in case you run into any difficulties.
Bushings should also be checked while you have the car on jack stands. Bushings are found in most locations where an arm or bar is connected to the frame. For example, the front control arm will have two pivot points that use bushings. One such point is C, shown in Figure 2. Sway bar, or stabilizer bar, bushings are notorious for wearing out, often needing replacement at 50,000 miles (D in Figure 3). Bad bushings are distorted, cracked and/or have splits in the material.
The final front suspension part that should be checked is the ball joint, E, shown in Figure 4. Be sure that the boot is intact. If it is torn, dirt and debris can damage the ball and socket assembly, causing accelerated wear. Check the appropriate service manual for the procedures to check ball joints as the method varies from vehicle-to-vehicle.
REAR SUSPENSION
A typical rear suspension will have a coil spring, F, a shock absorber, or strut, G, a trailing arm, or link, H, and a rebound bumper, J (Figure 5). If the car has a strut (depending on the design), check it in the same manner as the front strut. If it has a shock absorber, check for fluid leaks where the piston enters the fluid chamber, K, shown in Figure 6. To do this test, the car must be raised and the wheel removed in order to see the shock absorber. Any fluid means you need a new shock. The rebound test should also be performed with the car on the ground.
Next, check the coil springs, L, for any breaks (Figure 7). As with the front springs, any breaks will be seen on the pigtail at the end of the spring. Replacement of the rear springs also requires a spring compressor. Note: This is a dangerous procedure. Use extreme caution when compressing coil springs.
Finally, you need to check the rear bushings for the same type of damage that could be found on the front bushings. The vehicle might have a sway bar, depending on the design. Also, there could be trailing arms and control arms. Regardless, check all the mounting locations that use bushings, such as, M, shown in Figure 8.
