What should you do if your car shakes when you brake?

More and more drivers are noticing their car shaking when braking and are wondering whether this is a minor issue or a more serious fault. The symptom can vary. Sometimes it is only felt through the steering wheel, whilst at other times it is felt throughout the whole bodywork.

In this article, I explain the most common causes of vibration when braking. I show you how to carry out a preliminary check on the condition of the brake discs, wheels and suspension, when to resort to emergency measures, and what to expect after a visit to the garage.

Why does the car shake when braking?

The most common cause is uneven contact between the brake pad and the disc. The wheel, tyre or a suspension component may also be to blame.

Vibrations during braking are usually caused by uneven disc thickness or deposits of friction material on their surface following overheating. Vibrations can be exacerbated by a seized caliper, worn guides or corrosion on the hub, which warps the mounting of the disc or rim. A similar effect is caused by warped rims, poorly balanced wheels, or tyres with bulges or stepped wear. Worn control arm bushings, pins, links and bearings can transmit and amplify vibrations, thereby obscuring the true nature of the fault.

How can you tell if the brake discs are at fault?

A tell-tale sign is the pulsing of the brake pedal and the shaking of the steering wheel, which increase as the braking force increases.

At home, assessment is limited, but there are a few tell-tale signs. If the wheel runs smoothly on a raised axle without rubbing against the disc, this indicates that it is in better condition. A smooth disc with no discolouration or ridges suggests a lower risk of runout. A burnt smell after a short drive and a rim that is hot on one side may indicate a seized brake caliper. A definitive verdict can only be reached by measuring the runout and thickness of the disc at a service centre, and by inspecting the surface beneath the disc and on the hub.

Could vibrations be caused by uneven wheels or tyres?

Yes, a wobbly wheel often gives the impression of a brake problem.

A bulging tyre, a tyre that has been damaged after hitting a pothole, a warped rim or an imbalance cause vibrations that increase with speed. These become more noticeable when braking. Stepped tread wear and tyre pressure that is too low can produce similar symptoms. Professional wheel balancing with a road test, wheel straightening and a tyre pressure check using TPMS allow these causes to be quickly ruled out.

How can you tell the difference between suspension problems and brake system problems?

The location and nature of the vibrations suggest where to look for the fault.

With front disc brakes, the steering wheel usually shakes, whilst with rear disc brakes, the vibrations are felt more in the seat. If the vibrations occur even when not braking, increase with speed and appear on a specific stretch of road, the problem is more likely to be with the wheels or the suspension. Knocking noises over bumps, the car wobbling and uneven tyre wear indicate play in the suspension or poor wheel alignment. Jerks at the end of braking and a pulsating brake pedal are typical signs of warped brake discs.

When can you use emergency measures before seeing a mechanic?

Pull over to a safe place, switch off the engine and call a breakdown service or a mobile tyre repair service if the steering wheel pulls to one side, the brake pedal feels soft or there is a strong smell of burning.
In emergency situations, temporary measures may only be used if the vehicle remains controllable and brakes steadily.

In an emergency, it helps to drive calmly, keep a greater distance from other vehicles and use engine braking. It’s worth removing any mud or snow from the wheel rims, as they can cause the tyres to become unbalanced. It is worth adjusting tyre pressure to the levels recommended by the manufacturer. It is better to remove luggage and heavy items from the boot, as a heavily laden car brakes unevenly.

Will computer diagnostics identify the cause of the vibrations?

Indirectly, yes, but it doesn’t measure the mechanical runout of the discs.

The computer will read out ABS faults, problems with the wheel speed sensors, the brake system pressure sensor and corrections to the assistance systems. This helps to detect inconsistent wheel signals, which sometimes accompany damage to a bearing or sensor. Disc runout, a warped rim or seized guides can only be confirmed by mechanical measurements and a test drive.

What tests should a mechanic carry out in the event of vibrations?

• Measurement of the run-out and thickness of the discs, and assessment of the contact surface with the hub.
• Cleaning and inspection of hubs, corrosion and disc mounting components.
• Check the clamps, guides, anti-vibration pads and the condition of the brake pads.
• Check the brake fluid, flexible hoses and the condition of the wheel bearings.
• Wheel balancing with a road test, tyre assessment and wheel straightening.
• Assessment of suspension and steering play, measurement of wheel alignment, and a test drive with vibration recording.

What should you do immediately if you notice vibrations whilst braking?

The safest thing to do is to slow down, increase the distance between you and the vehicle in front, and drive calmly to a place where the car can be checked.

It is worth checking whether the vibrations are constant or only occur once the engine has warmed up. It is a good idea to note whether the steering wheel is shaking or whether the vibrations can be felt in the seat. A TPMS warning light or a visible difference in the tyres is a sign that the wheels need checking. If one of the brakes is clearly overheating and the car is pulling to one side, it is safer to stop driving and call for mobile breakdown assistance. In large cities, round-the-clock tyre services are available, including wheel balancing with a road test and the replacement of brake discs and pads, which reduces the time needed for diagnosis.

A thorough diagnosis saves you stress and money, whilst a well-maintained braking system ensures peace of mind behind the wheel. It’s worth starting with the wheels and brake discs, then moving on to the suspension and electronics. A quick response reduces wear and tear on other components and improves safety on every journey.

Book an appointment at the 24-hour tyre service and restore the car’s smooth braking!