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August 26, 2011

Car Talk

Slow is best on speed bumps

Syndicated columnists

Dear Tom and Ray:

I live in a gated community with lots of speed bumps to deter speeding. I am always amazed at the ingenious techniques people use when they go over speed bumps. There is the one-wheel technique, the diagonal technique and, of course, the old-man (3 mph) technique. I prefer the straight-on-at-20-mph technique. Which way is best for your car?
-- Frank

Tom: Well, the straight-on-at-20-mph technique is best for US, Frank. We sell a lot of suspension parts that way.

Ray: But what's best for the car? No question about it: The old-man (3 mph) technique. In fact, we're going to rename that approach the "genius technique."

Tom: When you hit bumps hard, like you do, Frank, you jolt every part of the suspension system. It's like whacking every part in the car with a hammer. And even though cars are built to take a certain amount of punishment, the more they take and the harder they take it, the sooner their parts wear out.

Ray: And what happens to older cars that have taken more than their share of hard knocks like that? They tend to squeak and rattle and chatter their way down the road, dropping occasional parts along the way (see also: any of my brother's heaps).

Tom: Whereas using the "genius technique" and going over a bump like that at 3 mph does practically no damage. The springs and shocks compress gently and absorb the bump, and then they decompress.

Ray: And there's certainly nothing wrong with staying to the right and avoiding the speed bump with your right-side wheels, as long as you combine it with the "genius" 3 mph approach.

Tom: And as long as you don't drive too far to the right, jump the curb and run over someone's prized tulips.

Ray: The same is true for the diagonal approach. It can't hurt, as long as you're going very slowly.

Tom: And besides, when you go 20 mph over speed bumps, you're defeating their whole purpose -- to stop knuckleheads from driving too fast in a pedestrian-heavy area. They're slowing you down for a reason -- so that kids and older folks and everyone else who walks or crosses the street is safer.

Ray: So, because of the damage you can do to your car, and to innocent pedestrians, we're renaming the straight-on-at-20-mph approach the "moron approach," Frank. So we'll leave it up to you to decide which technique you want to be associated with from now on.

(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk website.)

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