Suspension arm bush worn

What causes it

• Age and heat: the rubber perishes, cracks and eventually separates from its metal sleeve
• Pothole and kerb impacts tearing the bonded rubber internally
• An oil or power steering leak dripping onto the bush and softening the rubber
• Salt corrosion at the outer sleeve, particularly on cars that have spent winters on treated roads

Advisory or failure?

Grading follows how much movement there is. A bush that is slightly worn or beginning to perish is a minor defect — recorded on the certificate but not a failure — and early deterioration is often noted as an advisory instead. Once there is excessive movement in the joint it is a major defect and the car fails. Where the wear is bad enough that the arm could become detached, or where it affects the vehicle's steering or stability, the grading is dangerous. A minor defect here is still worth acting on: it means the item is on its way out, not that it is fine.

Can you fix it yourself?

Possible with care

Two very different jobs share this name. Fitting a complete control arm with the bushes already pressed in is a bolt-off, bolt-on job for anyone with axle stands, a torque wrench and a ball joint separator. Pressing new bushes into the existing arm needs a hydraulic press or a purpose-made puller and is not realistic on a driveway. Either way there is one trap that catches people out: bolts through suspension bushes must be tightened with the car at normal ride height, not hanging on the stands, or the bush is permanently preloaded and will tear itself apart within months. Have the tracking checked afterwards.

What it costs

A complete lower arm for a common hatchback is £40 to £90 in parts, with around an hour and a half of labour per side, so labour is the larger share. Doing both sides together — usually sensible, since they age at the same rate — plus a four-wheel alignment takes you to the top of the band. Seized or corroded subframe bolts are the main source of unplanned labour, and on some cars the bush is only supplied pressed into the subframe, which is a considerably bigger job.

What happens if you ignore it

A perished bush rarely leaves you stranded, but it lets the wheel move out of its designed position under braking and cornering, so the car steers least accurately exactly when it matters most. The steady cost is tyres — a wheel that cannot hold its alignment will scrub the inner edge off a front tyre in a few thousand miles. Left long enough the rubber separates entirely from its sleeve, the arm starts knocking against its mounting, and the wear spreads to the ball joint and the subframe around it.

Common questions

Is a worn suspension bush an MOT failure?

It depends how much movement there is. A bush that is slightly worn or beginning to perish is a minor defect, recorded but not a failure, and early deterioration is often noted as an advisory instead. Excessive movement in the joint is a major defect and the car fails. If the arm could become detached, or steering and stability are affected, the grading is dangerous.

Why does my car knock over speed bumps?

A dull knock or clonk from one corner over speed bumps and drain covers is the classic worn bush, and it is usually worst when the car is cold. The steering may also wander on the motorway and need constant small corrections. Plenty of worn bushes make no noise at all, because the tester finds them with a pry bar applying a load you cannot reproduce by driving.

Can you replace suspension bushes without a press?

Only by fitting a complete control arm with the bushes already pressed in, which is a straightforward bolt-off, bolt-on job with axle stands and a torque wrench. Pressing new bushes into an existing arm needs a hydraulic press or a purpose-made puller. Either way, bolts through suspension bushes must be tightened at normal ride height, not with the car hanging on stands, or the bush will tear itself apart within months.

How much does it cost to replace a suspension arm bush?

A complete lower arm for a common hatchback is £40 to £90 in parts, with around an hour and a half of labour per side, so labour is the larger share. Doing both sides together with a four-wheel alignment reaches the top of the band. Seized or corroded subframe bolts are the main source of unplanned extra labour.

What happens if I ignore a worn suspension bush?

A perished bush rarely leaves you stranded, but it lets the wheel move out of its designed position under braking and cornering, so the car steers least accurately exactly when that matters most. The steady cost is tyres: a wheel that cannot hold its alignment will scrub the inner edge off a front tyre in a few thousand miles. Left long enough, the wear spreads to the ball joint and the subframe.

Cars this happens to most

Of every model with at least 2,000 tests in the DVSA data, these record suspension arm bush worn on the largest share of their MOTs. Across all of them the typical rate is 4.3% of tests.

1. Nissan NV20025%

   6,221 times in 24,703 tests

2. Mercedes-Benz Clc23%

   1,805 times in 7,925 tests

3. Mazda 522%

   1,914 times in 8,764 tests

4. Chevrolet Aveo19%

   1,435 times in 7,366 tests

5. Nissan Primastar19%

   1,612 times in 8,383 tests

6. London Taxis Int TX419%

   1,957 times in 10,429 tests

7. Isuzu Rodeo16%

   689 times in 4,178 tests

8. Daihatsu Sirion16%

   857 times in 5,416 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 →

Other common defects

• Direction indicator not working
• Stop lamp not working
• Lamp of the wrong colour, position or intensity
• Brake pipe corroded
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