The car brakes intermittently: reasons and what the driver should do

Do you press the brake pedal, but instead of slowing down smoothly, the car jerks, vibrates, or brakes in waves? Intermittent braking is a common problem that is not only annoying, but also a security threat. In 80% of cases, worn-out brake system parts are to blame, but sometimes the root of all evil lies in the electronics or even the suspension. In this article we will analyze all possible reasons — from banal pad wear to rare malfunctions ABS and ESP, and also give step-by-step instructions for diagnosis and repair.

It is important to understand: if the brakes “pulse” when pressed, this is a signal of a problem that will only get worse over time. For example, Warped brake discs at speeds above 80 km/h can increase stopping distance by 30–40%, which is critical in an emergency. Do not delay the check - some faults are fixed in 15 minutes, others require the intervention of a car service.

We have collected the experience of craftsmen with 10 years of experience, official recommendations from manufacturers (Bosch, ATE, TRW) and data from technical bulletins of automakers. At the end of the article there is a checklist for self-diagnosis and answers to frequently asked questions.

1. Wear or deformation of brake discs

The most common cause of intermittent braking is uneven surface of brake discs. Over time, they wear unevenly and become covered with grooves or “waves” due to overheating. When you press the pedal, the pads cling to these bumps, creating a “jerking” effect.

How to check:

• 🔍 Visual inspection: Raise the car on a jack and spin the wheel. The brake disc should be smooth, without deep scratches or blue discoloration (a sign of overheating).
• 📏 Thickness measurement: Use a caliper. The minimum permissible thickness is indicated on the disc itself (for example, MIN TH 22 mm).
• ⚖️ Disc runout: When rotating the wheel, place the dial indicator on the surface of the wheel. Beat more 0.1 mm requires replacement or grooving.

What to do:

• 🔧 Disc groove: Possible if the thickness allows (usually up to 2-3 grooves during the service life). Cost - from 1,500 ₽ per axle.
• 🆕 Replacing disks: Optimal for thinner discs 20–22 mm or with deep furrows. Average price - from 3,000 ₽ per pair (Bosch or ATE).

⚠️ Attention: Grinding discs on a machine without removing them from the car (so-called “grinding in place”) often gives a temporary effect. The accuracy of such processing is lower than with professional equipment.

2. Poor quality or worn brake pads

Pads with a worn friction layer or cheap analogues made of “soft” materials often cause vibrations. When braking, they crumble, forming an uneven layer on the disc, or overheat, losing efficiency.

Signs of problem pads:

• 🚗 The braking distance has increased, the pedal “falls”.
• 🔥 After intense braking, you can hear the smell of burning.
• 🎵 A creaking or whistling sound appears (sometimes this is normal for new pads, but if the sound is constant, check the wear).

How to choose pads:

Pad type	Pros	Cons	Recommended Brands
Semi-metallic	Long service life, resistant to overheating	Noisy, work worse in the cold	Ferodo, TRW
Ceramic	Quiet, low dust, stable at any temperature	Dear ones, they may slow down worse on older disks	ATE, Brembo
Organic	Soft, silent, disc-friendly	Wear out quickly, not for aggressive driving	Textar, Pagid

⚠️ Attention: Never install pads from unknown brands (for example, “no-name” from online stores). They often contain asbestos or metal shavings, which destroy the rims within 5–10 thousand km.

3. Caliper or guides jammed

If the caliper does not press the pads evenly against the disc, braking becomes choppy. Most often the culprits are:

• 🔩 Jammed guides (due to corrosion or lack of lubrication).
• 🔧 Deformed caliper piston (for example, after overheating).
• 🛑 Torn caliper boot, which causes dirt to get inside.

How to diagnose:

1. Raise the car and spin the wheel by hand. If it rotates with force or “sticks,” the caliper is stuck.
2. After the ride, touch the rims. If one of them is hotter than the others, the caliper does not release the pad.
3. Remove the wheel and press the brake pedal. The caliper piston should extend smoothly, without distortion.

Repair:

• 🛠️ Cleaning and lubricating the guides: Use special caliper lubricant (not regular Lithol!).
• 🔄 Replacing the piston or caliper assembly: If the piston is rusted or deformed. The cost of a new caliper is from 4,000 ₽.

What happens if you drive with a stuck caliper?

In addition to intermittent braking, this leads to:

- uneven wear of the pads (one wears out 2–3 times faster);

- overheating of the wheel bearing (risk of its destruction);

- an increase in fuel consumption by 5–10% due to constant movement resistance.

4. Problems with brake hoses and hydraulics

The rubber hoses that connect the calipers to the brake system crack or swell from the inside over time, blocking the free flow of fluid. This results in “pulsating” braking, especially when the pedal is pressed hard.

Signs of hose failure:

• 💧 Brake fluid leaks on the inside of the wheel.
• 🛞 The brake pedal becomes “wobbly” or fails.
• 🔄 The brakes “grab” only after several presses.

How to check:

1. Inspect the hoses for cracks or swelling. Pay special attention to the attachment points to the caliper and body.
2. Have an assistant press the brake pedal while you watch to see if the hoses swell. If yes, replacement is required.
3. Check the brake fluid level in the reservoir. If it falls without visible leaks, the liquid may be escaping through microcracks in the hoses.

⚠️ Attention: It is recommended to change brake hoses every 4–5 years or 100,000 km, even if outwardly they look normal. As rubber ages, the risk of rupture under pressure increases.

5. Malfunctions of ABS and electronic systems

If the brakes jerk when smoothly pressing the pedal, and the icon is lit on the dashboard ABS, the problem lies in the electronic systems. Possible reasons:

• 🎛️ Faulty ABS sensor: Sends false signals to the control unit, causing the system to operate for no reason.
• 🔌 Oxidized contacts on the connectors of the sensors or unit ABS.
• 🖥️ Control unit failure (for example, after “lighting up” the car).

Diagnostics:

1. Connect the scanner (for example, ELM327) and check the error codes. Common codes for ABS:

   
   C0035 - Right front wheel sensor malfunction
   C0040 - left rear wheel sensor malfunction
   C0121 - low sensor signal level

2. Check the resistance of the ABS sensors with a multimeter. Norm - 800–1400 Ohm.
3. Inspect the connectors for corrosion or broken wires.

What to do:

• 🔧 Cleaning contacts: Use WD-40 or a special contact cleaner.
• 🆕 Replacing the ABS sensor: Cost - from 800 ₽ per piece. It is better to change in pairs (left and right on the same axis).
• 🔄 Flashing the ABS unit: In rare cases, resetting errors through diagnostic equipment helps.

Check fuses (usually F3 or F26 in the block)

Inspect ABS sensors for damage

Measure the resistance of the sensors with a multimeter

Check the voltage at the ABS unit connector (should be 12V) -->

6. Problems with suspension and wheel bearings

It would seem, what does the suspension have to do with it? In fact, play in the wheel bearing or ball joint can cause wheel runout, which is transmitted to the brake disc. As a result, braking becomes uneven.

How to check:

• 🚗 Raise the car on a jack and swing the wheel in horizontal and vertical planes. Backlash more 0.5 mm - a sign of bearing or ball wear.
• 🔊 When driving at speed 40–60 km/h a hum or crunch is heard - a sure sign of problems with the bearing.

What to do:

• 🔧 Replacing the wheel bearing: Average cost - from 2,500 ₽ per piece + work. On some models (for example, VW Golf 4) the bearing changes along with the hub.
• 🛠️ Replacing the ball joint: If there is play in the support, it needs to be changed urgently - this is dangerous for control.

7. Rare causes: from firmware to corrosion

If all of the above doesn't help, check:

• 🖥️ ECU firmware: On some vehicles (eg Renault Duster until 2018) there were problems with the operating algorithm ABS/ESPproblems that were resolved by updating the software.
• 🛡️ Brake disc corrosion: If the car has been left idle for a long time, the discs may become rusty. The problem usually goes away after a few hard braking sessions.
• 🔋 Low voltage in the on-board network: If the battery is discharged, the unit ABS may not work correctly.

Checklist: what to do if the car brakes jerkily

Follow this algorithm for self-diagnosis:

1. Inspect the brake discs for runout and wear.

2. Check the thickness of the pads (minimum 3–4 mm)

3. Make sure that the caliper moves freely along the guides

4. Inspect the brake hoses for cracks and leaks

5. Connect a scanner and check for ABS/ESP errors

6. Rock the wheel to check for play in the bearings

7. Check the level and quality of the brake fluid -->

If after checking all the points the problem remains, contact a car service for in-depth diagnostics. You may need:

• 🔬 Checking the brake booster (vacuum or hydraulic).
• 📊 Diagnostics of the control unit ESP at the stand.
• 🛠️ Wheel balancing (sometimes vibrations during braking are associated with imbalance).

FAQ: Answers to frequently asked questions

Why do the brakes only jerk at low speeds?

At speeds up to 20–30 km/h problems with ABS sensors or play in the suspension. The reason is that electronic systems work more actively at low speeds, and mechanical play is more noticeable when the pedal is pressed lightly. Check:

• Sensor status ABS (clean off any dirt).
• Play in wheel bearings and ball joints.
• Sensitivity Settings ESP (on some cars they can be reset through the on-board computer menu).

Is it possible to drive if the brakes pulsate a little?

Short answer - no. Even a slight pulsation indicates:

• Uneven wear of discs/pads (over time this will lead to cracks).
• Overheating of the brake system (risk of fluid boiling).
• Increased load on wheel bearings.

The exception is if the pulsation appears after replacing the pads and discs. In this case they need 200–300 km for lapping.

How much does it cost to fix intermittent braking?

The cost depends on the reason:

Problem	Cost of spare parts (₽)	Cost of work (₽)
Grooving brake discs	—	1 500–2 500
Replacing pads (front axle)	2 000–5 000	1 000–1 500
Replacing the caliper	4 000–8 000	1 500–2 500
ABS diagnostics	—	1 000–2 000

The average cost to eliminate intermittent braking is: 5 000–15 000 ₽, depending on the car model and the degree of wear of parts.

Why did the brakes start to jerk after replacing the pads?

This is a typical situation if:

• 🔧 Not smeared caliper guides (the pads are jammed).
• 🛠️ The pads were installed, incompatible with your drives (for example, ceramic ones for worn discs).
• 🔄 Forgot calibrate the caliper (on some models it is necessary to reset the piston position through the diagnostic scanner).

Solution: return to the service and request re-installation in compliance with the technology.

Could intermittent braking be related to the tires?

Yes, but indirectly. If tires:

• 🔄 Unbalanced — Vibrations during braking increase.
• 🚗 They have different tread patterns (for example, summer in the front, winter in the back) - this changes the grip of the wheels on the road, and ABS works unevenly.
• 💥 Deflated or damaged — leads to uneven distribution of braking forces.

Check the tire pressure and have it balanced if the problem appears after re-shoeing.