How small does a chip have to be?
The coin test, the wiper-sweep rule, and the one position on the glass where size stops mattering.
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0117 456 0192
bookings@brunswickvehicleglass.co.uk
Brislington, Bristol BS4 3QF
Mon–Fri 07:30–18:00 · Sat 08:00–14:00
Cameras & glass · 5 minute read
Why recalibration
Why recalibration
is not optional
The camera behind your mirror does not know the windscreen has been changed. It carries on reporting what it sees from where it thinks it is, and everything downstream believes it.
Was yours calibrated?
If somebody replaced your screen and did not recalibrate, we take standalone calibration work. Send the registration and we will tell you whether your car needed it.
Almost every car built in the last seven or eight years has a camera module bonded to the inside of the windscreen. Change the glass and that camera moves. Not by much. By enough.
A fraction of a degree, a long way down the road
The camera measures distance and lane position by where objects appear in its field of view. Its calculations assume it is mounted at a known height and a known angle. Move it a fraction and the error does not stay small: it grows with distance, because the geometry fans out.
At fifty metres a tiny angular error is a lane's width. That is the difference between the car seeing a vehicle in front of you and seeing one in the next lane.
The short version
The camera is not broken and it will not warn you. It is confidently reporting a picture taken from slightly the wrong place.
What it actually feels like
Nobody drives away from an uncalibrated fit and notices immediately. It shows up over weeks, as things that feel like the car being fussy rather than the car being wrong.
- Lane keeping tugging slightly early or late, usually on one side more than the other.
- Adaptive cruise sitting closer or further back than it used to.
- Emergency braking reacting to a shadow, a bridge joint or a parked car on a bend.
- Traffic sign recognition reading the speed limit off the wrong road.
Every one of those gets blamed on the system being oversensitive. Usually it is not the system.
Static, dynamic, and why it matters which
Static calibration puts the car on a level floor under controlled lighting with targets at measured distances, and tells the camera what it should be seeing. Dynamic calibration drives the car at a set speed on roads with clear markings and lets it re-learn.
Which one your car needs is set by the manufacturer, not by the fitter. Some require one, some the other, and some want both in sequence. A workshop that only offers dynamic will simply not be able to do certain cars properly.
This is also why static work has to happen somewhere with a level floor. It is not a side-street job, whatever anybody tells you.
Ask for the report
A calibration produces pass values and a printed report. If a fitter cannot hand you one, the reasonable assumption is that it was not done.
Keep it. Insurers ask for it after an incident, main dealers ask for it at service time, and a buyer's inspection will ask for it when you sell.
If your screen was replaced recently and nobody mentioned calibration, it is worth finding out. We do standalone calibration work and it comes up more often than it should.
Next
Three more
Three more
worth reading
Will a glass claim cost me my no-claims?
How windscreen cover usually sits apart from the rest of the policy, and the excess to expect.
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Defrosting without cracking the screen
Why a blast of hot air on cold glass is the fastest way to turn a stable chip into a crack.
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Where we calibrate
Dynamic calibration runs from wherever the car is. Static needs the level floor at the unit in Brislington, and we tell you which yours needs before you book.
Unit
Unit 4, Whitby Road, Brislington, Bristol, BS4 3QF
Same-day repairs
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