Squealing or metallic grinding when braking: causes and the faults that trigger it

1. 1. Worn brake pads

   Common cause

   Autopista names it as the most common cause: when the friction material runs out, the exposed metal rubs against the disc. RACE explains that some manufacturers fit an acoustic wear indicator that warns the pad is about to wear out and that, without one, a very high-pitched, loud squeal means there is no friction material left and the backing plate is rubbing directly on the disc. Autodoc describes that low, grinding noise as a sign of completely worn pads.^[1][2][3][4]

   Faults with with brake calipers and discs

2. 2. Scored, lipped or stepped discs

   Common cause

   RACE says that a worn disc leaves a lip that rubs against the pad and produces a softer noise, typical when braking at low speed at traffic lights; Autodoc talks about a step next to the edge that also causes squealing. RACE adds that scored discs lengthen the braking distance and that a warped disc makes the pedal pulse.^[1][2][5]

   Faults with with brake calipers and discs

3. 3. Damp, rust or dirt on pads and discs

   Common cause

   RACE states that, if the car stands for a long time, the discs rust and squeal on the first few stops until the rust disappears. Autopista adds that in very humid conditions or after heavy rain temporary squealing is common, and that dust, sand or small stones between pads and discs also cause noise; Diariomotor notes that damp is removed once the system reaches its operating temperature.^[1][3][6][7]

   Faults with with brake calipers and discs

4. 4. New pads not bedded in, of a different type or badly fitted

   Possible cause

   RACE explains that new pads have a small protective layer and that it is normal for them to squeal for the first few kilometres, and Autodoc speaks of a bedding-in period. Autopista includes faulty installation or low-quality components among the causes, and RACE points out that sintered pads can be noisier than organic ones. HELLA stresses bedding in the braking system after the repair.^{[1][2][3][8][9]}

   Faults with with brake calipers and discs

5. 5. Pads glazed by overheating

   Possible cause

   Autopista describes how, after prolonged braking, a glass-like layer can form on the pad, and that in this case they must be replaced as soon as possible. Diariomotor links glazing to repeated braking or braking on steep descents, when the friction material exceeds its working temperature.^[6][7]

   Faults with with brake calipers and discs

6. 6. Calipers or slides unlubricated or seized

   Possible cause

   According to Autodoc, retaining clips and slide pins without enough lubrication make noise. RACE warns that a caliper that stays partly applied causes overheating and makes the car brake less on one side, and blames a damaged dust boot, poor maintenance or expired brake fluid.^[2][10]

   Faults with with brake calipers and discs

7. 7. Lever handbrake not fully released

   Uncommon

   RACE notes that, if the car has a lever handbrake and you forget to release it completely, a rubbing noise can also be heard.^[1]

   Faults with with the handbrake

8. 8. Drum brakes with built-up friction material

   Uncommon

   Diariomotor points out that, in squealing drum brakes, the main cause is friction material that has built up because it was not removed.^[7]

1. Note when it makes the noise (first stops after rain or a long stop, at low speed, always or only under hard braking) and what it sounds like: high-pitched squeal, low grinding noise or vibration in the pedal.^[1][2][5]
2. If it has rained or the car has been standing, check whether the noise disappears after a few stops. Autopista suggests braking gently but firmly several times to clear the deposits, and RACE and Diariomotor point out that rust and damp go away on their own.^[1][6][7]
3. If the car has a lever handbrake, make sure it is fully released.^[1]
4. Ask for the pad thickness and the condition of the discs (scoring, lip or step at the edge) to be checked. Autopista recommends replacing them when wear is significant.^[2][3][5]
5. Go to a garage without delay if the pedal is softer or has more travel, vibrates, the car brakes worse or brakes less on one side, or if one wheel gets abnormally hot.^[4][5][10]
6. If you changed the brakes recently and the squeal persists after the first few kilometres, ask for the fitting and the lubrication of clips and slides to be checked. HELLA says discs are always replaced in pairs and with new pads as well.^[2][3][8]

Urgency: Garage soon

It depends on the noise. Autopista states that, in most cases, squealing is not a particular cause for concern, except for glazed pads, which must be replaced as soon as possible; if it persists, a specialist should inspect the system. A very high-pitched, loud squeal or a metallic scraping indicates, according to RACE and Autodoc, pads with no material left and the backing plate rubbing on the disc, and RACE recommends having the car checked if it brakes worse or makes a strange noise. None of the sources says how many kilometres you can cover with that noise.^[2][4][5][6]

1. • High severityFrequency: CommonOpel Zafira ASeized rear brakes and brake pipe corrosionRubbing or a metallic squeal from a rear wheel, or the car taking more effort than normal to pull away because of a brake that does not fully release.

   Source for the symptom in the Opel Zafira A^[11]

2. • High severityFrequency: CommonSuzuki Jimny IIIRusted brake pipes and poorly performing brakesWeak or uneven braking and an ineffective handbrake.

   Source for the symptom in the Suzuki Jimny III^[12][13][14]

3. • Critical severityFrequency: OccasionalToyota ProAce CityDefective front brake discs that may crack (Proace City Verso)Cracked discs may produce noise from the front brakes.

   Source for the symptom in the Toyota ProAce City^[15]

4. • High severityFrequency: OccasionalFiat SediciService and handbrake defectsWeaker braking or a handbrake that does not hold, found at inspection.

   Source for the symptom in the Fiat Sedici^[16][17]

5. • Medium severityFrequency: CommonFord Mondeo IIISeized rear brake calipersConstant metallic rubbing or squealing from a rear wheel, with that wheel hotter than normal after a drive.

   Source for the symptom in the Ford Mondeo III^[18]

6. • Medium severityFrequency: CommonRenault Scénic IIIPremature wear of the rear brakes due to the electric parking brakeContinuous noise or rubbing from the rear wheels because the electric parking brake does not release fully.

   Source for the symptom in the Renault Scénic III^[19]

7. • High severityFrequency: OccasionalSuzuki Grand Vitara IIBrake pipe defects in the inspectionPoor braking, or inspection failed for pipes and discs.

   Source for the symptom in the Suzuki Grand Vitara II^[20]

8. • Medium severityFrequency: CommonSuzuki Grand Vitara IIRusted or ineffective rear brakesRear brakes that are not very effective, with noises or seizing.

   Source for the symptom in the Suzuki Grand Vitara II^[21][22]

9. • Medium severityFrequency: CommonToyota Auris IThe rear brake discs wear and rust prematurelyVisible scoring or corrosion on the surface of the rear disc, sometimes with a rubbing noise, as well as seized rear caliper replacements in some cases.Appears at around 100,000 km

   Source for the symptom in the Toyota Auris I^[23]

10. • Medium severityFrequency: OccasionalCitroën C1 IIBrakes: worn discs, handbrake and brake hoses fail the inspectionNoise or uneven braking from worn discs; the source does not describe the symptoms in detail.

    Source for the symptom in the Citroën C1 II^[24]

11. • Medium severityFrequency: OccasionalCitroën C5 ISeized brake calipers on the Citroën C5, especially the rear onesNoise when braking and uneven wear of pads and discs.

    Source for the symptom in the Citroën C5 I^[25]

12. • Medium severityFrequency: OccasionalDacia Sandero IIWear and accelerated corrosion of the front brakesSquealing or metallic grinding when braking once the disc or pad is badly worn.

    Source for the symptom in the Dacia Sandero II^[26]

13. • Medium severityFrequency: OccasionalFiat TipoRusted rear brakes and insufficient braking at Fiat Tipo inspectionsLess effective braking and visible rust on the rear brakes.

    Source for the symptom in the Fiat Tipo^[27]

14. • Medium severityFrequency: OccasionalHonda Jazz IIRear brakes seizing and corroded discsNoises when braking, or a rear wheel that drags and gets hot after driving.

    Source for the symptom in the Honda Jazz II^[28][29]

15. • Medium severityFrequency: OccasionalHyundai i20 IIIRear brake calipers that seize through lack of useCreaking or squealing from the rear axle while driving, a sign that a rear caliper has seized.

    Source for the symptom in the Hyundai i20 III^[30]

16. • Medium severityFrequency: OccasionalKia Ceed IIWear of pads, discs and the parking brake systemThe report groups brake pads and discs among the items with the most defects detected at the periodic inspection.

    Source for the symptom in the Kia Ceed II^[31]

17. • Medium severityFrequency: OccasionalKia Rio IIIPremature rear pad wear and seizing calipersA metallic rubbing noise when braking and rear pads worn sooner than expected, according to fiches-auto.fr.

    Source for the symptom in the Kia Rio III^[32]

18. • Medium severityFrequency: OccasionalMazda 6 IBrake calipers and handbrake that seizeBrake drag, a burning smell, uneven pad wear or a handbrake that does not release.

    Source for the symptom in the Mazda 6 I^[33]

19. • Medium severityFrequency: OccasionalMazda MX-5 IIISeized calipers and worn discs and brake padsAutofácil refers to excessively worn discs and pads, without describing other symptoms.

    Source for the symptom in the Mazda MX-5 III^[34]

20. • Medium severityFrequency: OccasionalMINI Cooper F55Rear brake caliper that seizes and wears out the discs prematurely on the Mini F55Rapid wear of the rear brakes and, according to some reports, a pad wear warning very early (around 15,000 km).

    Source for the symptom in the MINI Cooper F55^[35]

21. • Medium severityFrequency: OccasionalMINI Cooper R56Seized rear brake calipers and damaged rear discs on the Mini Cooper R56The rear discs show a blue tint or deep scoring, and the brakes drag.

    Source for the symptom in the MINI Cooper R56^[36][37]

22. • Medium severityFrequency: OccasionalNissan Almera IISeized brake calipers on the Nissan Almera N16Noise or dragging from the brake on one wheel.

    Source for the symptom in the Nissan Almera II^[38]

23. • Medium severityFrequency: OccasionalOpel Mokka ARear brakes that seize and discs that warp on the Mokka ARubbing or heating of one rear wheel when driving.

    Source for the symptom in the Opel Mokka A^[39][40]

24. • Medium severityFrequency: OccasionalPeugeot 308 IPremature wear of brake discs and padsSquealing or a metallic noise under braking, sometimes from a seized rear caliper.Appears at around 28,000 km

    Source for the symptom in the Peugeot 308 I^[41]

25. • Medium severityFrequency: OccasionalRenault Clio IISeizing of the rear drum brakes and leaking wheel cylindersRubbing or overheating at a rear wheel because the drum or shoes have seized.

    Source for the symptom in the Renault Clio II^[42]

26. • Medium severityFrequency: OccasionalRenault Clio IVAbnormal front brake wear and seized rear drumsSquealing or a metallic noise from abnormal wear of the front pads and discs.

    Source for the symptom in the Renault Clio IV^[43]

27. • Medium severityFrequency: OccasionalRenault Laguna ISeized rear brake calipers and wheel cylindersDragging or noise from the rear wheels, uneven pad wear and a wheel that gets hot.

    Source for the symptom in the Renault Laguna I^[44]

28. • Medium severityFrequency: OccasionalRenault Twingo IPremature wear of brake discs and brake hoses on the Twingo IWeak or uneven braking and discs worn sooner than usual.

    Source for the symptom in the Renault Twingo I^[45][46]

29. • Medium severityFrequency: OccasionalToyota Corolla IXThe rear brake calipers seize and wear out the disc and padNoise or vibration when braking, uneven wear between the two rear pads, an overheated disc and sometimes a burning smell after driving.Appears at around 98,000 km

    Source for the symptom in the Toyota Corolla IX^[47]

30. • Medium severityFrequency: OccasionalToyota Prius IIIRear brake calipers seizing because of the guidesRear caliper that sticks, according to the reports on the page.

    Source for the symptom in the Toyota Prius III^[48]

31. • Medium severityFrequency: RareHyundai ix20Rear brake calipers seizingNoise when braking or rolling, and abnormal wear of the pads and discs.

    Source for the symptom in the Hyundai ix20^[49]

32. • Medium severityFrequency: RareKia VengaSeized rear brake calipersRubbing noise and premature brake pad wear.

    Source for the symptom in the Kia Venga^[50]

33. • Medium severityFrequency: RareRenault Espace VIBroken brake caliper spring on the Espace VIHigh-pitched squeal when braking with Auto Hold and, in one case, immobilisation because of a broken caliper spring.

    Source for the symptom in the Renault Espace VI^[51]

34. • Medium severityFrequency: RareSuzuki Swift IVBrake caliper failureNoises or uneven braking at the affected wheel.

    Source for the symptom in the Suzuki Swift IV^[52]

• Kia
• Renault
• Suzuki
• Toyota

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