MAX Car 109: Reducing Rolling Resistance

Reader Contribution by Jack Mccornack

I apologize for September’s lack of blog post—I was running around doing stuff, including attending the Seven Springs MOTHER EARTH NEWS FAIR, where I ran a little workshop on the Mother’s Pickup Experiment (MPX). Just before I left, I shot this video where the MPX, unmodified from its stock form (a 1994 Toyota Hilux with mumbledy-mumble miles on the clock), was the control group for a rolling resistance reduction demonstration, starring MAX.

MAX has obvious features to decrease its aerodynamic drag (though not so obvious in this video because I was working on some body mods that day and the doors and windshield were removed), and it also has some more subtle features to decrease its rolling resistance (Goodyear Assurance Fuel Max tires and Lucas Oil synthetic lubricants), which is a catch-all phrase meaning “all the drag that isn’t aerodynamic drag.”

Rolling resistance is all the little frictions—the drag of the wheel bearings, the drag of the gears stirring up the fluid in the transmission, the drag of the tires flexing as they roll—that dominate the total drag package at low speed. Rolling resistance (unlike air resistance) is pretty much constant; if you pushed your car with a bathroom scale between you and the back bumper, the poundage the scale would read would be about the same at a steady 1 mph or a steady 5 mph (or in theory, in a vacuum, a steady 50 or 100 mph). One result of this is, if you have a slope that is steep enough that your car will start rolling, it will keep rolling.

The access road at my local airport has a slight slope—slight enough that you sure don’t notice it when you walk on it, it’s only about an inch down for every ten feet forward. Most of the time you don’t notice the slope when you park on it, either, because most cars just sit there. In fact, the first time I got out of MAX out there and MAX wandered off on its own, I was pretty surprised. Since that day, I use the parking brake all the time*, regardless of how flat the road feels.

So here’s the video, with my usual goofball production values (or lack thereof). It only takes a minute to watch, and I hope you enjoy it.

Check out how to make your own MAX.

*It’s such a habit now that I left the parking brake on for my first take of this video. For the second (and last) take, I blocked the driver’s side rear wheel with a dime-sized piece of gravel, which was an easy rollover, and looked much more professional than pushing and grunting and going nowhere.

Video by Jack McCornack

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