Quick answer
Ball joints connect suspension and steering components while allowing movement. If worn, loose or damaged, they can affect handling and tyre wear.
Excessive play or insecure joints commonly lead to MOT failure.
When a ball joint can fail MOT
Excessive play
Movement beyond acceptable limits.
Split dust boot
Allows dirt in and grease out.
Knocking wear
Loose joints may produce suspension knocks.
Insecure fixing
Loose mountings or fastening issues.
Corrosion damage
Serious rust can weaken components.
Dangerous wear
Severe wear may risk joint separation.
Common symptoms of worn ball joints
Drivers may notice knocking over bumps, vague steering, uneven tyre wear, wandering alignment or clunks when turning.
Some worn joints show no obvious symptoms until inspected.
What to check before your MOT
1. Listen for knocks
Especially over potholes or speed bumps.
2. Watch tyre wear
Uneven wear can indicate suspension wear.
3. Check steering feel
Loose or wandering steering can be a clue.
4. Inspect boots
Split rubber covers often shorten joint life.
5. Ask for inspection
Garages can check play safely on a lift.
6. Repair promptly
Worn joints should not be ignored.
Should you repair it before MOT?
Yes. Ball joints are key safety components. Leaving worn joints can worsen tyre wear, steering feel and suspension noise.
If severe, they may become unsafe to drive with.
Related MOT and suspension guides
Frequently asked questions
Can ball joint fail MOT for split boot?
Yes, especially if wear or contamination is present.
Do ball joints knock?
Yes, worn joints often knock over bumps.
Can worn ball joints affect tyres?
Yes, they may cause uneven tyre wear.
Are they dangerous?
Severely worn joints can become dangerous.
Are repairs expensive?
Costs vary by vehicle and suspension design.
Best next step?
Get suspension play checked before the MOT.