Dear Tom and Ray:

I have a 1989 Lincoln Continental, which I purchased new. Shortly after the warranty expired, I experienced a front-end vibration when applying the brakes. This was diagnosed as brake rotor run-out. Resurfacing the rotors fixed it for about 1,000 miles, then the problem returned. I had the rotors resurfaced again, with the same result. I had new rotors put on, and the fix lasted about 20,000 miles before the problem recurred. I've now had those rotors machined twice. Machining fixes the problem, but after a short time it always comes back. I especially notice it in the mountains, where I do a lot of my driving. What's the problem? -- Donald

Tom: The mountains are the problem, Donald. You need to move closer to the ocean.

Ray: My guess is that you're overheating your brakes when you drive down long mountain roads. When rotors get real hot, they're most likely to warp.

Tom: So what can you do about it? Well, you could stop using your brakes in the mountains!

Ray: My brother has a brilliant answer for everything, doesn't he? Actually you CAN go down the mountains and use your brakes a lot less. Here's how: When you start a long descent, downshift into a lower gear.

Tom: Now I know that people who drive Lincolns don't ever think about stuff like downshifting. You bought the car because you wanted driving to be as effortless as sitting in your living room, right? Well, the truth is, downshifting is no more difficult than using the TV remote. So I know you can handle it, Donald.

Ray: Start by dropping it into 3rd gear, and go to second or first if need be. You want to find a gear that allows you to coast down the hill at a reasonable speed, letting the natural engine braking keep you from going too fast. You can use the accelerator to speed up a bit between curves, and then simply take your foot off the gas to slow down going into the curves.

Tom: Now, a lot of people who do this for the first time write back to us in horror and say, "The engine was screaming!" And we say, "Yeah, but don't worry about it." The engine is turning faster than you're used to, but it's not being overworked because it's acting as the brake. And as long as you don't accelerate to, say, 80 mph in 2nd gear and grossly over-rev it, you're not hurting the engine. (See your owner's manual for the maximum speed in each gear on your particular car.)

Ray: So give that a try, Donald. If you can reduce your dependency on the brakes during those long downhill runs, you should be able to go a lot longer between rotors. Good luck! *** Help safeguard your investment by ordering Tom and Ray's pamphlet, "Ten Ways You May Be Ruining Your Car Without Even Knowing It!" Send $3 and a stamped (55 cents), self-addressed, No. 10 envelope to Ruin, PO Box 6420, Riverton, NJ 08077- 6420. *** © 1999 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

Auto repairs can be costly! Save money by ordering Tom and Ray's pamphlet "Ten Ways You May Be Ruining Your Car Without Even Knowing It!" To order, send (check or money order) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475. You can also order online.

© 1999 by Tom and Ray Magliozzi and Doug Berman Distributed by King Features Syndicate, Inc.

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