Friday, September 19, 2014 Detailed Auto Topics
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Vehicle designers use tie rods to connect the steering linkage to the wheels of a vehicle. Tie rods are very durable and require little attention. Should they fail, we may lose our steering. Occasionally inspecting the condition of our tie rods can easily prevent a catastrophe.

A broken tie rod end will result in loss of steering 

Tie rods similar to small ball joints and allow up and down movement and rotation of the steering components. A tie rod can both turn and pivot which maintains the connection between steering and wheels as the suspension moves.

Inner and outer tie rod ends with threaded adjustment for setting toe 

Tie rods normally come in pairs, an inner and an outer. They normally use threads to connect the inner and outer tie rods. Rotating the threads causes them to screw in and out of the components. This changes the distance between the two rod ends. This adjustment changes the angle to the tires and is the way we set the toe in a wheel alignment.

Tie rods turn and move so lubricant is necessary to prevent wear. They hold lubricant in and debris out by the flexible rubber boot around the tie rod base. Damage to the boot means the lubricant leaks out and contaminants get in to wear the joint. Once the protective boot fails, the joint inevitably fails as well. Replacing most boots is not possible, so failure eventually means a new tie rod.

Once the tie rod boot is damaged the joint will fail

Once the boot is damaged the tie rod end will fail 

Some tie rods have provisions to be greased but most today are sealed. While greasing may seem like a great idea, improperly greasing a joint is worse than not lubricating it at all. Too much grease causes the protective boot to tear.  Another problem is not cleaning the grease fitting before attaching the grease gun.  This allows debris, that is on the zerk fitting, to enter the joint along with the lubricant. 

The lubricant used should also be correct for the application.  An improper grease may not offer adequate protection and could attack the rubber in the protective boot.  Always check service data for the proper lubricant, if there is any doubt.

Worn out tie rods

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.  This is sometimes accompanied by a squeak noise when turning and a loose feeling in the steering.

Broken tie rod resulting from missing grease boot

A broken tie rod is extremely dangerous, as this is the link between the driver and the tire. When the rubber seal fails, the lubricant is loss. Debris enters the joint and rust may form. This quickly destroys the tie and a quick pull may cause it to separate.  When this occurs, we lose control of the steering.

Spring loaded tie rod ends

Cutaway view of a spring loaded tie rod end 

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 must 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 to make good tie rods appear to have slack.

Properly checking tie rods

Improperly checking a tie rod can damage it

Properly checking tie rods is best done on a wheel alignment rack. The wheel is supported so that it is free to move, but still at normal height.  When properly supported the tie rods are not hanging down, rather running at their normal angles.  Checking tie rods that hang at an angle may give a false indication of being bad.  Pushing in and out at the front of 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.

Properly checking tie rods for slack by pushing in and out on the tires 

Because of their extreme importance to safety, tie rods are always very securely fastened to the vehicle. Many use a taper lock to hold the joint firmly in place. 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 the nut from coming loose.

Taper lock on a tie rod end 

Removing tie rods from their mounting is best done with 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

 tire wear

Properly greasing tie rods that can be greased and replacing tie rods when the boots tear will assure years of problem free use.

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