Fun Fact Friday - You spin me right round

Baby, right round (in a record-like fashion, one might say). Today is Lori's and my fifth wedding anniversary. I love her deeply, and somehow, she still puts up with my nonsense and nerdiness. Since the traditional gift for 5th anniversaries is something wooden, I could have taken the low road here. Or I could have discussed the origin of the 2x4. Fun stuff.

Not, however, as much fun as positraction. Ooh, limited slip differentials. Talk to me baby, that's the stuff. I know, I'm a big romantic at heart.

The topic came up Wednesday night, because Lori's truck is making an odd whining, whirring noise. Because it strains like the transmission can't shift, but the transmission shifts just fine, I thought it could be the differential. Of course, it wouldn't make the noise for me today.

Even though the modern automobile has always had four wheels, it took modern science and Ferdinand Porsche to realize that wheel spin could be controlled. When turning a corner, the inside tires are spinning more slowly than the outside tires. If the tires spin equally, the inside tire will either force the car back into a straight line, or squeal annoyingly, so as to impress members of the female persuasion. Same thing as when we pull away from a light.

What? They pulled us aside in Driver's Ed to tell us that girls like that sort of thing.

Really.

However, by building a clutch mechanism into the differential, it can allow the gears to turn asynchronously in turns. However, in a straight line, the differential can again resume equal power to both tires, which results in those cool dual burnout marks.(Anything, ladies?)

Of course, there's lots of science-y stuff behind this, that I've never been able to comprehend. If you're really curious, check out DrivingFast.com, they know how to get their nerd on big time.

And if you just want gratuitous movie nerdiness, identify the following:

"Because there is no way that these tire marks were made by a '64 Buick Skylark convertible. These marks were made by a 1963 Pontiac Tempest. The car that made these two, equal-length tire marks had positraction. You can't make those marks without positraction, which was not available on the '64 Buick Skylark!"

Cinematic genius.