Triumph Bonnevill common MOT failures and failure rate
What a Triumph Bonnevill fails its MOT on, from real DVSA test data, and the part that resolves each item.
Based on 88 MOT tests in DVSA data.
About 20.5% of MOT tests recorded on the Triumph Bonnevill in DVSA data end in a failure. The same handful of items account for most of them.
Its most common failure is brakes, which makes up 33.3% of the Triumph Bonnevill's failures, followed by brakes, other, steering, tyres. Each item below links to the part that resolves it. Confirm the exact fitment against your registration or VIN before buying, and have safety-critical work done by a competent mechanic.
What it fails on, and why
Brake failures cover worn pads and discs, an imbalance between wheels, corroded or scored discs, or a binding caliper. Braking efficiency is measured on a rolling road, so a spongy or pulling brake shows up as a low reading.
This covers a range of smaller items, from a non-working horn to a warning light left on.
Steering faults are typically worn track-rod ends or ball joints, play in the rack, or a split gaiter letting grease out and dirt in. Excessive free play at the wheel fails.
Tyres fail for tread below the 1.6mm legal limit across the central three-quarters, uneven or exposed-cord wear, or sidewall damage. The tester inspects all four; a single illegal tyre is a fail.
A missing, damaged, dirty or incorrectly-spaced number plate, or one using the wrong font, will fail. A replacement plate is inexpensive.
The parts that fix each
If your car has just failed, you have 10 working days to fix the items and get a free partial retest. These are the usual parts; confirm the exact fitment against your registration or VIN before buying.
Other models
Sources: DVSA MOT History API: MOT test results and defect data ยท DVSA MOT testing data for Great Britain