Your car has started knocking when you go over potholes, the steering feels a bit looser than it used to, and the front tyres are wearing unevenly. Nine times out of ten that is the tie rod ends on the steering tie rods, sometimes the tie rod itself. It is a part of the front suspension that hardly anyone looks at until it starts causing trouble, and it has a big impact on how the car holds a line and how it behaves in a corner.
What tie rods and tie rod ends are and what they do
The tie rod is a metal bar that transfers movement from the steering rack to the wheel. When you turn the steering wheel, the rack pushes or pulls the tie rod, and the tie rod turns the wheel. Each front wheel has its own tie rod, so two in total.
The tie rod end is a ball joint at the end of the tie rod, where the tie rod connects to the wheel hub. It is the joint that lets the wheel turn left and right while the car is at the same time moving up and down over bumps. The tie rod end is protected by a rubber boot filled with grease. When the boot tears, the grease leaks out, dust and water get inside, and the joint starts wearing out fast.
The most common failure point is exactly the tie rod end. The tie rod itself is usually a solid bar that lasts a long time, while the tie rod end wears out much faster because it is in constant motion and is exposed to impacts from the road.
Symptoms the driver feels
The classic signs to watch for:
- Knocking when going over potholes, bumps and speed humps. A dry, metallic knock coming from the front of the car. You usually hear it first at low speed, driving through a yard or over rough tarmac.
- A loose feel in the steering. The car reacts with a small delay, as if the steering wheel has play before the wheel actually turns. You will often hear a quiet knock when you flick the steering wheel left and right while the car is standing still.
- Uneven, "patchy" wear on the front tyres. The tyre does not wear in a straight line but in patches, with some spots on the tread worn down and others almost untouched. That is the result of geometry that constantly shifts because the joint is loose.
- Vibration in the steering wheel at certain speeds. Most often between 80 and 110 km/h, though it depends on the car.
- Pulling to one side. The car does not track straight, you have to constantly correct it with the steering wheel.
It is important to tell these symptoms apart from other suspension issues. A hum that grows with speed is usually a wheel bearing. A body that bounces and keeps bouncing after a bump points to the shocks. Vibration that is strong at idle and calms down while driving usually comes from engine mounts. The combination of knocking over bumps, a loose steering wheel, and odd tyre wear is almost always a tie rod end or tie rod.
How a mechanic checks tie rods and tie rod ends on the lift
The check is quick and does not need expensive equipment, just experienced hands. The car goes up on the lift so the front wheels hang in the air.
The mechanic grabs the wheel at the 3 and 9 o'clock position (so the sides) and tries to wiggle it in and out. If you feel play and hear a knock, the problem is almost certainly in the tie rod or the tie rod end. Then the hands move to the 12 and 6 o'clock position (top and bottom of the wheel) and the same motion is repeated, up and down. That mostly reveals problems with the wheel bearing and ball joints, not with the tie rod end.
Along with that check, the boot on the tie rod end is always inspected. Visually, by eye. If the boot is torn or cracked, if you can see grease on it or around it, the tie rod end is practically due for replacement. It is not a question of if but when. Water and dust are inside, the joint is in the process of failing, and waiting means risking it letting go at the worst possible moment.
An experienced mechanic does all of that in half a minute per wheel. That is why in our shop, every time a car is on the lift for some other job, we routinely check the tie rod ends as well. Thirty seconds of work that often saves the driver from both a costlier repair and a dangerous situation on the road.
When the tie rod end needs replacing, and when the whole tie rod
If the problem is only in the tie rod end, and the tie rod is intact and not deformed, only the tie rod end is replaced. That is the cheaper and more common job. The tie rod end is unscrewed from the tie rod, the new one is screwed on, set roughly to the right length, and the car goes for an alignment.
The whole tie rod is replaced in a few situations: when the tie rod itself is bent (most often from a heavy hit on a pothole or kerb), when the thread on the tie rod is damaged so the tie rod end cannot be screwed on properly, or when the ball at the inner end of the tie rod (where it connects to the steering rack) is worn. That inner joint is a less common failure point, but when it goes, it requires replacing the whole tie rod.
An important detail: tie rod ends are always replaced in pairs, left and right side together. The reason is that they wear at a similar rate. If one is gone, the other is usually close to it, so it makes no sense to do the car twice. With the tie rod itself it is different, that gets replaced as needed, one or both.
Why it should not be put off and what comes after the replacement
Driving with worn tie rods is not just a matter of comfort and tyres. In the worst case, the tie rod end can fully give way, the ball joint pops out of its seat, and the wheel turns independently of the steering wheel. That happens rarely, but it does happen, usually during a sharper manoeuvre or when crossing a bigger pothole. The consequences are clear.
When a tie rod end or tie rod is replaced, the car always goes for a wheel alignment. Without that, the replacement is half a job. The wheels will not be pointed properly, the tyres will be wrecked quickly, and the car will pull to one side. We do not do replacement without alignment, that is just how it goes.
The alignment itself is done on a special machine with optical or laser sensors. The angles of the front wheels and, if needed, the rear wheels are measured, and the tie rods are adjusted so that all the parameters fall within factory values. The job takes between half an hour and an hour, depending on the car and how far off the parameters are.
If your car has started knocking or you feel that the steering is no longer what it used to be, drop by the shop and we will check the front suspension. It is better to deal with it while it is still just the tie rod end, than to wait until it turns into a costlier job or a story on the road that could have ended badly.