The MOT Files

MOT defect file

Brake drum or shoe worn or contaminated

Last updated

Quick answer

On a drum brake, the friction lining is down to its limit or has been soaked in oil or grease. Contaminated linings cannot grip properly, which is why the tester treats it the same as having no material left.

Typical cost
£130–£320
DIY viability
Garage job
Drum brake section with worn lining and an oversize drumA drum brake is shown square-on with its circular backplate, wheel cylinder and two curved shoes inside the cut face of the drum. The right shoe has only a thin friction lining left, and three rivet heads now reach its working surface. The drum's red working surface lies outside the dashed maximum diameter datum, showing that the drum is worn oversize. Rivets can score the drum and both worn components require replacement.Drum brake in sectionWheel cylinderBackplateRivets at lining surfaceWorn drum surfaceMaximum diameterDrum wear and lining thickness are exaggerated
A drum can fail if it is significantly worn or beyond its marked maximum diameter. A shoe worn to its rivets is also unsafe because the rivets can contact and score the drum. Radial wear and lining thickness are exaggerated here for clarity.

What you might notice

  • A handbrake that needs more clicks than it used to, since on most cars the rear drums are what it acts on
  • Scraping or rhythmic rubbing from the back of the car that changes as you brake gently
  • The rear of the car stepping out slightly under braking, or an obvious pull to one side
  • Frequently nothing, because the linings are hidden inside the drum and only come to light when the drum is removed

What causes it

  • Simple mileage — rear linings last a long time, so they are often the original set and eventually reach the limit
  • A leaking wheel cylinder soaking the lining in brake fluid, which is the most common contamination route
  • A failed axle or hub seal letting gear oil or grease onto the friction surface
  • Seized self-adjusters, so the shoes never take up the slack and only a narrow strip of lining does any work

Advisory or failure?

Friction material worn down to 1.5mm or less is a major defect and a failure, and that limit applies to drum linings as well as to pads. Linings or shoes contaminated with oil, grease or brake fluid are also a major defect, because contaminated material cannot generate the friction it was designed for however much of it is left. A drum that is excessively worn, scored or has a cracked friction surface is major; one that is fractured, insecure or missing is graded dangerous. A drum that is simply corroded on its outer surface, with the friction face sound, is not a defect.

Can you fix it yourself?

Garage job

Drum brakes are more awkward than the disc brakes most people cut their teeth on. The drum itself often has to be driven or pulled off after backing the adjuster right off, the shoes are held by return springs and retaining pins that need a specific pair of pliers, and the whole assembly has to go back in exactly the right orientation or the self-adjuster will not work. Add the handbrake mechanism, which usually has to be disconnected and reset, and the fact that a leaking wheel cylinder found inside means opening the hydraulics and bleeding. The lining dust should not be blown around or breathed in. It is achievable if you have done it before, but it is not a good first brake job.

What it costs

A set of shoes is £25 to £50 and drums are £40 to £90 each, so parts are modest. Labour is where it goes, because drum work is slower than disc work — budget an hour and a half to two hours per axle. Shoes alone on a straightforward car are £130 to £190; shoes, drums and a wheel cylinder with a bleed lands at £250 to £320. What pushes it to the top is a drum rusted solid onto the hub, a seized handbrake cable that has to be replaced at the same time, or an integral wheel bearing that has to come out to get the drum off.

What happens if you ignore it

Once the lining wears through to the metal shoe, the rivets and the shoe itself score the drum, which turns a £60 set of shoes into a drum as well. Contaminated linings are worse in a way, because they give little warning — the pedal feels normal and the brake simply does not deliver when asked, and the imbalance across the axle can swing the back of the car out under hard braking in the wet. On most cars the rear brakes are also the parking brake, so worn or oily linings usually mean the handbrake will not hold on a hill and will not reach the 16% it needs. Continuing to drive on it is both an MOT failure and a roadworthiness offence.

Common questions

How thin can brake linings be before they fail the MOT?
Friction material worn to 1.5mm or less is a major defect and a failure, and that limit applies to drum linings just as it does to disc pads. A drum that is excessively worn, scored or has a cracked friction surface is also major, while one that is fractured, insecure or missing is graded dangerous.
Are oily or contaminated brake shoes an MOT failure?
Yes, contaminated linings are a major defect however much material is left, because friction material soaked in oil, grease or brake fluid cannot generate the grip it was designed for. The usual sources are a leaking wheel cylinder soaking the lining from inside the drum, or a failed axle or hub seal letting gear oil through.
Is a rusty brake drum an MOT failure?
Not if the corrosion is on the outer surface only and the friction face inside is sound. Surface rust on the outside of a drum is normal on any car that has been through a British winter and is not recorded as a defect. It becomes one when the friction surface itself is scored, cracked or worn past its limit.
Why does my handbrake need more clicks than it used to?
On most cars the handbrake acts through the rear drums, so worn linings, seized self-adjusters or a stretched cable all show up as extra lever travel. Take it seriously, because the same worn rear brakes that add clicks will often also fail to reach the 16% parking brake efficiency the MOT requires, giving you two failure items.
How much does it cost to replace brake shoes and drums?
Shoes are £25 to £50 a set and drums £40 to £90 each, so labour dominates at an hour and a half to two hours per axle. Shoes alone on a straightforward car are £130 to £190, while shoes, drums and a wheel cylinder with a bleed lands at £250 to £320. Drum work is not a good first brake job.

Cars this happens to most

Of every model with at least 2,000 tests in the DVSA data, these record brake drum or shoe worn or contaminated on the largest share of their MOTs. Across all of them the typical rate is 2.1% of tests.

  1. Citroen C4 Grand Picasso5.7%

    816 times in 14,355 tests

  2. Nissan X-Trail5.4%

    4,785 times in 88,138 tests

  3. Chevrolet Orlando5.4%

    182 times in 3,392 tests

  4. Ssangyong Musso5.3%

    175 times in 3,313 tests

  5. Nissan NV2505.2%

    117 times in 2,243 tests

  6. Kia Carens5.2%

    711 times in 13,720 tests

  7. Ford Grand C-Max5.0%

    1,737 times in 34,572 tests

  8. Volkswagen Tiguan Allspace4.8%

    295 times in 6,181 tests

A high rate here is a property of the fleet as much as the car: these models skew old, and almost everything fails more with age. It is a reason to check the item on a used example, not proof the model is badly built. Models with fewer than 2,000 tests are left out because a rate drawn from a few hundred cars moves too much to rank.

Pass rates for every make and model

The warning light behind this

This defect is what a tester writes down. What you see from the driver’s seat is a symbol, and it is worth checking which one, because manufacturers reuse the same shape for more than one system.

This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.

Has this been recorded on your car?

Check the full MOT history for any UK registration.

Spaces are optional

Other common defects