You press the brake pedal, and from under the wheels or hood area there is a distinct knock, grinding or metal clang? It’s not just an annoying sound – it’s a signal that a malfunction has occurred in the brake system or suspension. Ignore knocking during braking cannot beThey may indicate wear and tear of critical parts that can fail at any time. At best, you risk being left without brakes in the parking lot, at worst – on the highway.

In this article, we will understand All possible causes of knocking during braking - from banal wear of the pads to backlash in the hub bearings or weakened caliper fasteners. You'll find out how diagnose the problem on your own (even without a pit), what sounds indicate, and when you can do minor repairs, and when to urgently go to the station. For clarity added table of correspondence of sounds and malfunctions, as well as checklists for checking each node.

1. Worn brake pads are the most common cause of knocking

If the knocking occurs foot-step And it disappears with strong braking, the shoe is to blame in 80% of cases. And it’s not just about erasing them completely: even new shoes can knock if installed incorrectly or have a marriage.

How to determine that the knock comes from the pads:

  • 🔊 Sound.: metallic grinding or tapping (as if a nail scratches a disk). It is increased by slow braking.
  • 📍 Localization: knocking is heard from the side of a particular wheel (for example, only from the front left).
  • 🚗 Behavior: with sharp braking, the knock may disappear - the pad presses closer to the disc.

What do I do? Inspect the pads through the spokes of the disc or remove the wheel. Minimum thickness of friction layer - 2-3 mm. If less, a replacement is required. Also check:

  • 🔧 Presence wear-indicator (metal plates that begin to scrape across the disk when critical wear is applied).
  • 🔄 Luft pad in guides They should sit tight, without gaps.
  • 🛠️ Condition of anti-script plates (If they are worn or missing, the pads will "walk" and knock).
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If the pads are new, but knock - check whether there is dirt or a small stone between them and the disk. Sometimes it is enough to clean the surface with a metal brush.

2. Deformed or worn brake discs

Brake discs are the second most frequent culprit of knocking. Reasons:

  • 🔥 Overheating (For example, after a long period of deceleration). The drive drive drives, and there are microcracks.
  • 💥 Strike. (Kicking a curb, a hole) The disc bends, and the pad hits the uneven surface.
  • ⏳ Natural wear and tear. The minimum thickness of the disc is indicated on its end (usually 18-22 mm for passenger cars).

How to check the disk without removing:

  1. Lift the car on the jack and spin the wheel manually. If the disk is deformed, you will feel beat Or you'll see the pad bounce.
  2. Examine the end of the disk for the subject burrican (protruding edge). Its height shall not exceed 1 mm.
  3. Check the temperature of the disc after braking. If he hot-touchedAnd the pads are cold -- the drive drive drives.
What happens if you drive with a curved disk?

The deformed disc not only knocks, but also worsens braking: the pedal vibrates ("beats"), the braking distance increases. In critical cases, the disc may crack, which will lead to a complete loss of brakes on one wheel.

3. Luft in the caliper or its guides

Supports are “ticks” that press the pads against the disc. If the stains are stained or stained, the ears will be heard. thumpSometimes with vibrations on the pedals.

Causes of backlash:

  • 🔩 Weakened mounting bolts calipers to braces.
  • 🛢️ Dried or missing lubricant on the guides.
  • 🔄 Wear of rubber anthers They are the ones who are the ones who are the ones who are the ones who are the ones who are the ones who are the ones who are the ones.

How to diagnose:

  1. Press the brake pedal and see if the caliper shifts relative to the disc. If so, there's a backlash.
  2. Swing the caliper up and down. A healthy caliper should not be "walking".
  3. Remove the pads and check the guides for corrosion or lack of lubrication.

To inspect the bolts of the caliper attachment for a puff

Check the backup of the caliper with your hand

Ensure the integrity of the guide anthers

Lubricate the guides with a special paste (not Litol!)

Check the progress of the piston caliper (should move smoothly)->

4. Wear or breakage of brake brackets

The braces (aka "brake shields") hold the caliper and pads. When they are deformed or cracked, they appear clapEspecially with heavy braking. More often, brackets on the rear drum brakes break, but this is possible on the disk system.

Signs of malfunction of the bracket:

  • 🔊 The knocking is heard even when pedal-touch.
  • 🚗 The car leads away when braking (the brace does not fix the shoe exactly).
  • 🔧 You can visually see that the staples crooked.

What do I do? The braces are not repaired, only replacement. You need to change the pair (on both wheels of the axle), even if the second one looks whole. The cost of a brace for most models - from 1,500 to 4000 rubles per piece.

Once every 10,000 km (according to the regulations)

Only when there are knocks or creaks

I've never checked it myself.

I only trust the STO--

5. Suspension problems: hub bearing, ball, Silent blocks

If the knocking during braking is accompanied by steering-wheelThe problem may be in the sling. Braking creates an additional load on the nodes, and the backlashes appear brighter.

What elements to check:

Node. Signs of malfunction How to check
Stack bearing Hum when driving + knocking when braking, vibration on the steering wheel Raise the wheel on the jack and sway it in the horizontal plane. Luft is here - the bearing is dead.
Ball-pillar Knocking from the front when braking on irregularities, "failures" when pressing the pedal Push the mount between the lever and the swivel fist. If there's a backlash, replace it.
Silentblocks Deaf knock during braking at low speeds, moving the car away Check for cracks and ruptures of rubber. When you wear it hard, it's a walker.
Stabilizer struts Knocking during braking on corners, body rolls Shake the hand. If you hear a crunch or backlash, it’s time to change.

It's important.: Suspension knocks are often disguised as brake knocks. To determine the source, try to brake. motor-drive (no pedal pressing). If the knocking remains, the problem is the suspension.

6. Weakened fasteners: from wheel bolts to calipers

A banal but dangerous reason. loosening. When braking, the load on the nodes increases, and the backlash is manifested by knocking. What to check:

  • 🔧 Wheel bolts/nuts. If not stretched - the wheel can shift when braking, hitting the hub.
  • 🛠️ Caliporal mounting bolts (see para. section 3).
  • 🔩 Nuts of shock absorber racks. If weakened - the rack "walks", and a knock is heard at the top of the suspension.
  • 🚗 Brake shield anchorage (on rear drum brakes).

How to check:

  1. Take it. dynamometer and check the moment of tightening of all critical bolts (see the values for your model in the manual).
  2. Shake the part with your hand. Any backlash. - an excuse to tighten the mounts.
  3. After tightening, make a test drive: accelerate to 40-50 km / h and brake sharply. The knocking must disappear.
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If after lifting bolts knock remained - look for the problem deeper. Weakened mounts often mask wear of parts (for example, a loose caliper may indicate a broken brace).

7. Brake drums: specificity of the rear wheels

In cars with drum-brake (e.g., VAZ 2107, Renault Logan, Kia Rio Before 2015) knocking during braking can come from:

  • 🔊 Worn-out drums.. On the inner surface, a side is formed, on which the pads are beaten.
  • 🛠️ Untwisted pads. They are fixed by springs - if they are stretched or broken, the pads "walk."
  • 🔧 A jammed cylinder.. The shoe does not move away from the drum, overheats and knocks.

How to diagnose:

  1. Remove the wheel and drum (WD-40 may be required if it is boiling).
  2. Examine the inner surface of the drum for the subject deep-sulcus.
  3. Check it out. pad-walkThey should move freely, but not hang out.
  4. Make sure that return-spring Whole and resilient.

Attention.Drum brakes require more attention than disc brakes. They need to be cleaned and regulated every 15,000 to 20,000. km, otherwise the risk of knocking and uneven braking increases.

8. Other possible causes: from ABS to handheld

If you have checked all of the above, but the knocking remains, pay attention to:

  • 🚨 ABS sensor. If it is contaminated or damaged, it can be distributed during braking. knocking (It's like a hammer hitting the metal.)
  • 🔄 Parking brake cable. If it is pulled or jammed, the pads do not move completely and knock on the drum/disk.
  • 🛠️ Worn brake hoses. When braking, they can "pulsate", creating a knock in the caliper.
  • 🔧 Corrosion on brake discs. If the car stood for a long time, rust forms on the discs, and at the first braking, a grinding sound is heard.

For the diagnosis of ABS:

  1. Connect. OBD-2 scanner and check for errors (codes) C0035–C0050 indicate problems with sensors).
  2. Look at this. sensor-wiring for rubbing or oxidation.
  3. Check it out. gap between sensor and comb (should be 0.5-1.5 mm).
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If the knocking only occurs when first-brake Then, in the morning, it is the rust on the disks that is to blame. It is enough to brake intensively several times to clean the surface.

FAQ: Frequent questions about knocking when braking

The knocking during braking appeared after replacing the pads. What's up?

Probable reasons:

  1. The pads are set. subsize (For example, instead of 140 mm, we took 139 mm.)
  2. Not greased. caliper Or anti-script plates.
  3. Wrong. garnished new pads (need 100-200 km of careful braking).
  4. Marriage of pads (found in cheap brands like Fenox or LPR).

Solution: remove the pads, inspect for defects, lubricate all rubbing surfaces and repeat the run-in.

Knocking is heard only at low speeds (up to 30 km / h). What is it?

Typical reasons:

  • 🔧 Luft in step-bearing (knocking increases on corners).
  • 🛠️ Wearing plumblock Or the stabiliser bush.
  • 🚗 Weakened. caliper-strap.
  • 🔊 Rock or dirt between the pad and the disc.

Diagnostics: Lift the car on the jack and spin the wheel manually - it is easier to hear the source of the knock.

Can I drive if the knocking during braking is weak?

No, you can't.. Even a slight knock indicates:

  • Wear of brake mechanisms (risk of brake failure).
  • Luft in suspension (deterioration of handling).
  • Damage to the hub bearing (may jam the wheel).

Exception: if the knock appeared after washing or rain and disappears through 1-2 braking (this is water in the brake mechanisms).

How much does it cost to eliminate knocking when braking?

The cost depends on the reason (price for Moscow, 2026):

Problem. Cost of work (ruble) Cost of spare parts (ruble)
Replacement of brake pads (front) 800–1 500 1,500–4,000 (per set)
Drainage/replacement of brake discs 1 500–3 000 2,000 to 8,000 (per disc)
Repair of the caliper (replacement of guides, lubrication) 1 000–2 500 300–1000 (set of guides)
Replacement of the hop bearing 2 000–4 000 1,500–5,000 (per bearing)
Replacement of ball support 1 500–3 000 800–2,500 (per ball)

Tip: If the cause is unclear, start with free diagnostics (Many of them are available for repairs).

How to temporarily eliminate knocking if there is no time for repairs?

Provisional measures (Not more than 1-2 weeks!)

  • If the pads knock, clean them of dirt with a metal brush.
  • If the back is in the caliper, pull up the mount bolts (but don't pull it over!)
  • If the sling knocks -- slow down And avoid extreme braking.

⚠️ Attention.These measures do not eliminate the problem, but only mask it. The risk of brake failure remains!