ArcaMax

In some engines - appropriately nicknamed crashers (more formally known as interference designs) if the timing is really off, there is the possibility of catastrophic mechanical failure resulting from a valve opening (pushing into a combustion chamber) at the same moment the piston is traveling upward. If they kiss - bad news.

Luckily, there are very few crasher engines out there - and you probably do not own one. But regardless, it's important to check your owner's manual and service recommendations to see whether your car needs periodic timing belt replacements.

Timing belts are more common in Japanese/import-brand cars, while timing chains are more common in American brand cars - especially American cars and trucks withoverhead valve (rather than overhead cam) V8 engines. The chains are usually good "for life" and while they may stretch a little at some point way down the road, many miles from new, they rarely fail. Timing belts, on the other hand, will eventually fail if not replaced per the recommended intervals (it's typically every 75,000-120,000 miles). It won't hurt the engine if that happens. Usually - assuming it's not a crasher engine. But it will leave you dead in the water wherever you happen to be - and at the mercy of whatever repair shop happens to be nearby.

Better to get the belt replaced when the book says to get it replaced - when it's convenient for you and you've had a chance to shop around for the best deal on the work.

* Understeer vs. oversteer-

The easiest way to grasp these often talked-about (but rarely well-explained) terms is to talk about which set of wheels break traction first.

If the back end of the car (rear wheels) begins to slide toward the outside of the curve, the car is oversteering. If uncontrolled, the back end of the car will swing around and you'll be looking back the way you came.

If the front wheels lose traction (and slide) first, the nose of the car will try to keep on going in whatever direction inertia was carrying it - usually (in a corner) toward the outside of the curve. You probably won't experience a 180 (or a 360). You'll usually just run off the road onto the shoulder.

Front-wheel-drive cars tend to understeer because they are nose heavy - while rear-drive cars tend to oversteer because they are light in the tail.

If the car is an understeering car, backing off the throttle will help transfer some of the weight (of the car and momentum) rearward, which should help it recover traction.

Conversely, keeping on the throttle will help an oversteering-inclined rear-drive car hold its line by weighting the rear wheels, which enhances traction. But it's not instinctive to keep your foot down in a fast curve. It's something that you have to learn to do.

This by the way is why most production cars tend to understeer; in a panic situation (skid/slide) the average driver's instinct is to back off the gas. Understeering - also called plowing - is generally safer for the novice driver to deal with than oversteer.

FWD cars with transaxles tend to be nose heavy because the weight of the engine, transmission/axle (transaxle) is mostly up front while in a rear drive car, the components are spread out more evenly along the length of the car - engine up front, transmission mounted behind it (rather than bolted to it sideways) and a separate axle back where the rear wheels are.

The FWD car is usually better in snow because of that weight on the drive wheels, which enhances traction - and because the drive wheels pull rather than push the car. A RWD car is usually not good in snow because the drive wheels (the rear wheels) don't have much weight on them and so tend to break traction sooner and more easily on slippery surfaces.

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www.ericpetersautos.com or EPeters952@aol.com for comments.