Triumph Thnderbird storm vs Triumph Unknown: reliability comparison
MOT pass rates, common faults and mileage compared from real UK MOT data.
Triumph Thnderbird storm
83%
MOT pass rate · 1 vehicles
Triumph Unknown
89%
MOT pass rate · 65,927 vehicles
Verdict: On MOT pass rate the Triumph Thnderbird storm (83%) and Triumph Unknown (89%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.
Head to head
| Measure | Triumph Thnderbird storm | Triumph Unknown |
|---|---|---|
| MOT pass rate | 83% | 89% ✓ |
| MOT failure rate | 17% | 11% ✓ |
| Faults & advisories per test | 1.5 | 0.6 ✓ |
| Dangerous-fault share | 11% | 2% ✓ |
| Average mileage | 30,424 mi | 16,601 mi |
| Sample size (vehicles) | 1 | 65,927 |
Most common faults
Triumph Thnderbird storm
- Rear Brake disc(s) slightly scored (3.2.A1l)
- Nearside Front shock absorber has light misting of stanchion (2.3.3)
- Rear Roller brake test indicates slight fluctuation of brake effort (3.3.A1d)
- Front Brake disc(s) slightly worn (3.2.A1l)
- Front Tyre worn close to the legal limit (4.1.3(ii))
- Nearside Front Indicator damaged but working
Triumph Unknown
- Exhaust noisy (8.1.1 (a))
- Exhaust noisy (7.1.2)
- Front Roller brake test indicates slight fluctuation of brake effort (3.3.A1d)
- COVID-19 6 MONTH EXTENSION
- Rear Tyre worn close to the legal limit (5.2.3 (e))
- Steering headbearing has slight free play (2.2.2)
Reliability FAQ
On MOT pass rate the Triumph Thnderbird storm (83%) and Triumph Unknown (89%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.
Full Triumph Thnderbird storm report Full Triumph Unknown report Most reliable cars
Pass rates are computed over completed (pass/fail) MOT tests. Reliability also depends on age, mileage and upkeep — see each model's page for the full picture.