Last week, Apex Nürburgring owner Robert Mitchell revealed the tragic tale of his unfortunate fifth-to-second downshift in a Toyota GR Yaris.
While going for fourth on the Nürburgring racecourse in Germany, Mitchell accidentally grabbed second, which led to a mechanical overrev, though thankfully, he put the clutch back in while it was happening. Initially, the Yaris ran fine afterward, and Mitchell did a few more laps with it, but the next day, the car died on track.
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Apex decided to take apart the engine, as the miss-shift has voided the Toyota’s warranty, and with the valve cover removed, the damage is clear. The overrev led one of the intake valves to float, and with the piston pushing against the valve, the rocker arm that pushes on the valve spring failed. This caused the valve to be stuck open, which meant the cylinder lost all compression.
All things considered, the damage isn’t too bad, thanks to Mitchell quickly putting the clutch back in and letting the engine return to normal operating speed. Had he not done that, it’s likely that at least one of the other two cylinders would’ve lost compression, and there’d be debris all throughout the engine.
Fixing the car will be difficult, largely because the GR Yaris is such a new model. Toyota hasn’t distributed service manuals for the car, and parts availability is likely limited, so unless Apex can get an assist from Toyota itself, this car will likely sit a while.
This is a very good reminder that even though modern engine technology has come so far, there’s no way to prevent a mechanical overrev. And we’ve all grabbed a lower gear than intended before. It’s just that when you’re on track already at high revs, it’s easy to send an engine well past its redline. A simple, honest mistake with catastrophic consequences.
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