Why does my car vibrate?

Introduction

Whether your car is vibrating at high speeds, when idle, when accelerating or when braking, chances are the fault can be put down to one of these five reasons.

When your car vibrates, it’s a mild but consistent annoyance that only those who have experienced it will understand. It doesn't help if you have no idea why it's happening! There are a few reasons why your car may be vibrating or shaking, and some are more obvious than others.

We'll start with the most likely reason first, leading up to the grand finale for you poor souls out there who have come to the end of your tether.

Where to look

1. Tyres

   First thing’s first; check your tyres. This is the most common source of vibrating, and is most obvious if you are experiencing vibration when driving at speed.

Wheel balance

Tyres that are out of balance will cause shaking while driving at higher speeds (usually around 50-70mph). A tyre is out of balance when one section of the tyre is heavier than another. Out-of-balance tyres can cause vibration in the steering wheel, through the seat, and through the floor (steering wheel - front tyres; seat/floor - back tyres). An experienced mechanic can balance tyres, using a computerised wheel balancer that will measure the imbalance before weights are added to correct it.

Wheel alignment

Tyre balancing should not be confused with wheel alignment - wheel alignment is to do with the angle at which your wheels hit the road.

If you feel a vibrating steering wheel, it is likely that the vibration is coming from misaligned wheels. Your wheels can become misaligned from something as simple as hitting a pothole.

A mechanic will be able to align your wheels using a wheel alignment machine.

Faulty tyres

Vibrating or bouncing could be caused by a broken or slipped belt, which would cause uneven wear on your tyres.

Your tyres may need to be replaced if the vibration is left too long, and tyres have uneven wear. Poor quality tyres are likely to wear out sooner, and worn tyres can be dangerous, so it is important to keep on top of them.

2. Brakes

   If the vibration only happens when you hit the brakes, then that is probably where the problem lies. Don't worry, this sounds a lot scarier than it is.

   You may find that your brake discs have become warped over time, which means that the brake pads and callipers can't get enough grip when you apply the brakes. To fix this you can either get the brake parts machined again so they sit true, or you may have to replace them if they have worn down too much.

3. Worn parts

   There are several other parts that can wear out over time, and can cause vibration. These are struts or shocks, upper strut bearings, ball joints and tie rod ends. These parts would need to be replaced in order to fix the problem.

4. Resonance in the exhaust

   This problem may occur following a change in exhaust system (changing muffler/tailpipe), a bent pipe that touches the chassis, or a broken pipe. Also, if the original tuning weights have been removed or are missing, an annoying vibration may occur.

5. Powertrain

   OK, so you've looked at your tyres, your brakes and other parts. If everything looks like it's in good condition, and your tyres are balanced, you need to check the powertrain next. This is a bit of a bigger job, as the powertrain is made up of the engine, clutch, gearbox, drive shaft and differential.

   The first step here will depend on whether your car is an automatic or manual.

For a proper inspection of the powertrain, you may need to book a service with an experienced mechanic, as the cause of the vibration could be an issue with the inner CV joints - which can be hard to diagnose, especially in a rear-wheel vehicle. Problems with inner CV joints will usually also occur at higher speeds (60mph+), so if your car is vibrating at high speeds, and you've checked your tyres, unfortunately you might have a powertrain problem.

Conclusion

We hope this guide goes some way to helping you diagnose why your car is vibrating. However we do advise that you take your car into a garage to have a professional mechanic look into it, as they will know exactly how to test your car to find the fault and fix it.