Anti-roll bar linkage ball joint has slight play: what it means
"Anti-roll bar linkage ball joint has slight play" means one of the drop links, the short rods connecting the anti-roll bar to the suspension, has started to wear. It's one of the cheapest suspension repairs there is, and it isn't usually dangerous at this stage. If you can hear a knock over bumps, get it done in the next few weeks. If you can't hear anything yet, it can wait for your next service.
What drop links do
The anti-roll bar is a steel bar that runs across the car and links the left and right suspension. When the car leans in a corner, the bar twists and pushes back, keeping the body flatter. Drop links are the short rods at each end that join the bar to the suspension strut or arm. Each one has a small ball joint at the top and bottom.
Those ball joints are small and work hard, especially on rough roads. They're a common wear item, which is why this advisory turns up on so many MOTs.
The tell-tale noise
A worn drop link makes a hollow knock or rattle from the front of the car, usually most obvious:
- going slowly over speed bumps
- on broken roads at 20 to 30mph
- when one wheel hits a pothole
The car normally still drives straight and the steering feels normal, which is a good way to tell it apart from a worn track rod end or ball joint.
When it fails the MOT
The MOT manual doesn't list anti-roll bar links on their own. They're checked under the general suspension rules. Slight play gets an advisory. A link that's excessively worn or insecure is a major defect, and one that's missing or likely to come off, affecting how stable the car is, is dangerous.
In practice, if the tester has noted slight play this year, there's a fair chance it'll be worse by the next test.
What it costs
| Job | Rough price |
|---|---|
| Drop link part, each | £15 to £40 |
| Fitted at an independent garage, per side | £50 to £130 |
| Both sides together | Usually less than twice the single price |
Doing both sides at once makes sense. If one has worn, the other has done the same miles on the same roads. Drop links don't normally affect wheel alignment, so you shouldn't need tracking afterwards.
Is it a DIY job?
On a lot of cars this is one of the easier suspension jobs. There are usually just two nuts, one at each end. The catch is that the ball joint stud often spins when you try to undo a rusty nut. Most links have an Allen key or Torx socket in the end of the stud, or flats for a spanner, to hold it still. A bit of penetrating oil the night before helps.
If the nuts are badly seized, they may need cutting off, at which point a garage with the right tools is quicker.
Anti-roll bar bushes
You might also see an advisory about the anti-roll bar bushes. Those are the rubber mounts holding the bar to the subframe. Worn ones make a similar knock or a creak. They're usually cheap parts, and on some cars a quick job, on others it means lowering the subframe.
What to do now
If it's knocking, book it in with any other suspension work. If there are bush or ball joint advisories too, read the suspension bush guide, since it often makes sense to do everything on one corner in a single visit.
For a full list of what's on your MOT and how urgent each item is, use the MOT advisory decoder.
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