New-fangled Brakes Beat The Skids

February 22, 1992

Q. I hear so many ads lately about cars that have anti-lock brakes. What does that mean? I have driven cars for 63 years and have never had the brakes lock, except when I wanted them to. So what are these new brakes? -- John C., Summerfield, Fla.

--A. It seems the technology on everything in our lives is changing so fast it makes the head spin. And this is no exception.

Vehicles skidding out of control is a major cause of accidents, especially rear-end mishaps. The advent of computer chips has created a mechanism that can monitor the wheel spin to the degree that an impending lock-up can be sensed and at the same time prevented. An electrical pulse controls the pressure on the brakes, finessing the brakes so you do not lose control and begin skidding.

In my opinion, this device and the air bag are probably two of the greatest safety features in recent automotive history.

--Q. Our 1988 Chevy Nova develops a front-end vibration between 60 and 70 mph when you let up on the accelerator just a little. I am guessing a wheel balance problem. -- H.H., Ocala

--A. I doubt this is caused by the wheel balancing, as that should occur most noticeably at a specific speed rather than on acceleration or deceleration. In the front-drive axles there are bearings and joints comprising the drive system. Something is worn or broken that should be attended to.

--Q. My 1983 Volvo sedan has 60,000 miles. A few months ago, it began to develop a severe vibration between 28 and 32 mph. On fast acceleration, there was a loud metal-to-metal clang. The service shop replaced the transmission rear bearing, three driveshaft U-joints, and the left and right upper ball joints. This got rid of the clang and reduced the vibration by 50 percent. The vibration is most severe on acceleration and mild on deceleration. Deceleration in neutral is milder still. There is no discernible vibration in neutral. Any help? -- Walter J., St. Augustine

--A. It would seem you have a driveshaft misalignment that is aggravated by acceleration and deceleration. It is possible something has happened to the engine transmission mounts that may be the cause of this misalignment during acceleration. I would replace the mounts. If the problem persists, the mounts on the rear need to be replaced as well.

--Q. I have a 1985 Oldsmobile Toronado with 71,000 miles on it. The car runs fine except for one problem: After it gets to running temperature, there is a sort of rumble, like something running off center. Riding normally there is no sound, but slowing down in traffic, then picking up speed causes this rumble, along with a clicking sound. It is not like a valve click or rod knock. I read that a worn U-joint could cause a click. My mechanic says that is possible, but as long as it runs great it can do no harm. -- Gary K., Manchester, N.H.

--Q. My 1989 Lincoln Continental has a heavy rumble when I accelerate hard on takeoff. It feels like the tires have flat spots. Is this problem in the tires or the transmission? -- William E., Green Bay, Wis.

--A. It sounds as if both of these writers have a worn ``U-joint`` or a CV joint, since I believe both of these are front-wheel-drive cars. I would not let either of these go unattended. Depending on the mileage and the fact that these are both ``luxury`` cars, some of the work may be covered under warranty.

----``Big Daddy`` Don Garlits answers technical questions of general interest on automobiles but cannot personally respond to all letters. His answers are intended to point out possible solutions to problems and may not apply in every case. Send your questions to Don Garlits, in care of Tribune Media Services, 64 E. Concord St., Orlando, Fla. 32801.

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