All cars and trucks use tie rods to connect the steering to the wheels. They are durable and require very little attention but failure means loss of steering. Occasionally inspecting their condition can easily prevent a catastrophe.
Tie rods are flexible ball joints that allow steering and movement of the suspension. There are at least two tie rods on each wheel, an inner and an outer. The inner and outer tie rods are connected by threads. This allows for adjusting the toe on the tires during wheel alignment.
Tie rods must be lubricated to prevent wear. Lubricant is held in and debris is kept out by a flexible rubber boot. When this boot is damage, the lubricant gets contaminated and debris enters the joint.
Once the tie rod boot is damaged the joint will fail
Some tie rods have provisions to be greased but most today are sealed. While being able to be greased may seem like a great idea, improperly greasing a joint is worse than not greasing at all. Too much grease will cause the protective boot to tear. Not cleaning the grease fitting before greasing allows debris to enter the joint. Of course the proper grease must also be used.
Eventually tie rods can wear out. As the tie rod wears it develops slack in the ball and socket. This slack allows the toe to change and the vehicle will wear the tires. Vehicles that seem to get out of alignment, often have worn tie rods.
Many tie rods are also spring loaded. A very powerful spring pushes the ball into the seat as the joint wears. This provides a joint that is shock resistant as well as wear tolerant.
Care should be used in checking tie rods for wear. Many good tie rods are needlessly replaced, sometimes with inferior aftermarket parts. The old method of squeezing the joint with a pair of pliers should never be used. This can damage the spring and quickly ruin a good tie rod. Unscrupulous operators have used this "tactic" for years.
Properly checking tie rods is best done on a wheel alignment rack. The wheel is supported so that the tie rods are not hanging down, rather running at their normal height. Pushing in and out on the tires will quickly show if there is slack in the tie rods. Inner tie rods are sometimes covered by a rubber cover on rack and pinion steering. In this case the cover is squeezed so that any slack can be felt.
Because of their extreme importance to safety, tie rods are always very securely fastened to the vehicle. Above the attaching threads is a taper. This taper matches another in the mating component. When the parts are pulled together by tightening the nut, the tapers lock together. There is also a castle nut with a cotter pin to prevent accidental loss of the nut.
Removing tie rods from their mounting is best done with special tools made for the purpose. Beating on the tie rod or thread will only damage the part. Wedge shaped tools, driven between the tie rod and mount will destroy the boot and should only be used when the tie rod is going to be replaced.
Symptoms of bad tie rods include:
squeak when turning or on bumps
loose feeling in the steering
shaking in the steering on bumps
Properly greasing tie rods that can be greased and replacing tie rods when the boots tear will assure years of problem free use.