CASE STUDY
Steve Gooch’s twin-turbo Thunderbird should be a pretty familiar sight to readers, and we’d go so far as to call it the coolest Thunderbird in the country. With the power its twin-turbo 416ci Windsor was making, Steve encountered no end of issues, and, after methodically working his way through them, he was left scratching his head at a persistent driveline vibration at the top end of the dragstrip, around 190kph and up.
After even more research, he came to the conclusion that his two-piece driveshaft was the cause of the problems, but do you think he could find any information about the optimal set-up for two-piece driveshafts? Nope — as they’re primarily the reserve of new vehicles, optimal universal-joint operating angles are sorted during vehicle development. In an aftermarket application, like Steve’s, the best you can really do is educated guesswork.
“I’d been chasing a high-speed vibration after the drags and found a really good website. If you google ‘Spicer driveshaft torsional analysis’ there is a cool calculator,” Steve explains. “Driveshaft angles, especially on a two-piece, are like rocket science. I could not find any good info until I found that Spicer page.”
The information he discovered was enough to help him get to the bottom of the issue, as you’ll see.