In today's letter: Tom and Ray help Kathy with the finer points of shifting an automatic transmission.

Dear Car Talk

Dear Car Talk | Sep 01, 2006

Dear Tom and Ray:

A recent Car Talk column about downshifting left me with another question. You said that when going down a long, steep hill, you should shift your automatic transmission into a lower gear, like third, second or first. But here's my question. Whenever I shift my automatic transmission, like from park to drive, or from drive to reverse, it's always with the car stopped and my foot on the brake. Do I have to stop the car and put my foot on the brake before shifting down to third, second or first on a steep hill? -- Kathy

TOM: No. The car only needs to be stopped if you're changing directions or shifting into or out of park. But you can shift between forward gears while you're driving.

RAY: Just to remind everybody, we said that when you're descending a long, steep hill, you want to avoid "riding" your brakes all the way down because they can overheat and fail. True, that's the quick way down the mountain, but it's not the way you want to go. Trust me.

TOM: The best way to avoid riding the brakes is to shift to a lower gear and let the engine do some of the braking.

RAY: So here's the routine. If you find yourself going down a long, steep hill, and you notice that you're constantly on the brakes, move the shifter down one gear. You should feel what we call "engine braking," and the car should slow down. The engine will sound louder -- maybe a lot louder -- but that's fine. You're not doing any harm.

TOM: If you find that you still need to ride the brakes to keep the car at a reasonable speed, shift down another gear. You should feel even more engine braking now. And if you need to, shift down again, all the way to first gear. I've been on plenty of mountain roads where I had to shift all the way down to first just to keep from soiling my trousers!

RAY: Once you're in a gear that keeps the car's speed under control, you can then use the gas pedal to speed up between turns, and then just take your foot off the gas pedal to help slow you down again. You'll find that it's much easier to keep the car under control this way.

TOM: And once you get to the bottom of the hill, you shift back into drive and go on your merry way, Kathy.

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