I agree with Stahl on the Viper.

Something happened to lock the rears up.

In a kart, it would be like "sticking" the motor at the end of a straight: rears lock and you're around faster than you can blink.

I think it happens way too suddenly to be an overzealous trail-brake situation.

Also, I don't think it was a "money shift," as when I think of that, I think of it happening during an upshift.

It was either a mechanical failure (but there's no smoke) or a botched downshift like Stahl suggested.

Off to the GTO...

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If you're in control, you're not driving fast enough -- Parnelli Jones