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Hey, youíre out of line

By

Dennis R. Franklin
Franklin's Tire and Suspension
Yuma, AZ

 

With the advent of front wheel drives and more sophisticated alignment equipment the old "front end alignment" is obsolete. The manufacturers require a Thrust Alignment or a 4-wheel alignment, not to be confused with 4 wheel drive trucks. If you have a front wheel drive vehicle the manufacturer probably recommends a 4-wheel alignment, thrust at a minimum. If itís a pickup or you have an older car, it will probably require a thrust angle. All manufactures give a range from and to, with a preferred setting for "normal driving". If you use your vehicle outside of those perimeters the preferred settings are only a place to start Ėnot stop. If you tow, alter the suspension, put on different tires and wheels, use the vehicle strictly around town, load it or you have a wear or handling problem that is different, then "preferred" settings are in order. So before you get an alignment remember these tips.

  • Think twice about having an alignment done at a shop if they donít ask any questions and just say, "give me your keys".
  • Be prepared to explain just what it is that makes you believe the alignment is out. Without a symptom there is no problem.
  • Make sure the fuel tank is full. Alignment specs are setup with that in mind
  • Ask around to find out whom to go to. Your friends and the people you come in contact with should be able to tell you both where to go or not to go.

Ok, why thrust angle and what was wrong with the old "front-end alignment". It all has to do with the equipment doing a much more precise job. In a nut shell, the old equipment read the position of the opposite tire, left to right and right to left. The new equipment references the position of rear tires plus the fronts. Now lets move on to angles and specifications. All manufacturers give a range, from and to with a preferred setting. The preferred setting is for 1 and Ĺ people, full tank of gas and "normal" driving. (Iím still trying to find out what normal driving is). If you use your vehicle outside of those perimeters, the preferred settings are only a place to start Ėnot stop. A good alignment man will ask a lot of questions before he starts his test drive. Yes, to do it right the car is driven before and after the alignment. Remember those 9 little things I mentioned that can cause a vehicle to pull? That and many other things will be checked during the test drive. If the tech doesnít drive it this doesnít mean he wonít do a good alignment, he just might not fix your problem.

Now, lets take a look at those funny numbers and angles. Camber- is measured in degrees and refers to the top of the tire leaning in or out. If the wheel is leaning outward it is positive camber; leaning inward and you have negative camber. Positive camber is normally designed into the car to add more stability, road isolation and transfer the bearing load towards the inside bearings. Because of this your vehicle may wear the tires on the outside and be normal. Donít be too alarmed, the loss to tire life is measured in just a few thousand miles therefore most vehicle manufactures deem that as "acceptable ". Put on negative offset wheels or wider tires and everything changes. If you change to a different type of tire than the one that came with the vehicle, do nothing but hard stops, load the vehicle with more than "normal" loads and Preferred specs go out the window. A good alignment man will always want to see the old tires, read them and ask questions relating to the use of the vehicle. His job at that point is to balance or compromise camber angles to give the customer the best of everything. This is not an exact science and requires years of experience to master. There are two other angles that relate to basic alignments. Caster and toe in. Caster is a driving angle and generally will not cause tire wear. Without going into details, caster along with another angle, SAI (steering axes inclination), causes the steering wheel to return. It also gives the vehicle directional stability. Works just like the front wheel on a bicycle. You turn the handlebars and the top of the tire leans into the turn (camber). Ever ride a bike with your hands off the bars? Thatís directional stability provided by caster. But because caster causes the tire to lean it can cause tires to wear on the shoulders. Put on wide tires or wheels that stick out and, you guessed it, preferred specs goes out the window. Simply stated, caster needs to be adjusted to fit the configuration of the vehicle as well as the use of the vehicle, preferred specs are not for everyone. The last angle is called "toe". If you point your shoes together, pigeon toed, you are toed in. Stand at attention with your shoes pointing out at a 45-degree angle and you are toed out. This is by far the most critical angle there is.

To toe or not to toe that could be the question.

As I stated, toe is the most critical angle. In fact itís so critical that the spec. range for most cars is less than a ľ of an inch. This example should give you an idea. If I took an average size tire and cut the tread off, split it and laid the tread flat on the ground. For every 1/8 of an inch that the toe is out that piece of tread will be dragged 8 feet sideways. A brand new 80,000-mile tire can get totally worn out in 5000 miles if the toe is out ľ inch. So much for mileage warrantees. But just like the other angles, toe can be sensitive to vehicle height and loading. So if you have tire wear problems more than likely itís a toe problem. Remember I said height sensitive, which means if you raise or lower a vehicle the geometry has changed and that includes toe. A good alignment man will ask questions, read the old tires and test-drive the vehicle.

In summery there is some very good equipment out there that can walk a moron through an alignment. And to complicate things there are fewer and fewer good alignment technicians in the market place. (I wonít go into those reasons now) So no matter where you are, if you need some work done on your vehicle just ask around; ask anyone you come in contact with. It could be a waitress a check person at the grocery store, anyone. And pretty soon one establishment will be mentioned more than any other. Donít rely on a chain store name as a sign of quality; rely on what the locals say.

Remember that this report is provided as a free public service of this web-site. The author is not an employee of either provider and has no association with either. Information is considered to be accurate to the best of our knowledge. As of the above date the information is Copyrighted, the sole property of the author, and unauthorized reproduction is prohibited.

Drive safe,

 Dennis R. Franklin

 

How to!

An easy way to pull out burned or broken Christmas bulbs ( the small ones) is to take a 3" long nail clipper apart and use the jaws of the clipper to grasp under the plastic part of the bulb, squeeze carefully and pull.

To take apart the nail clippers,  squeeze them by hand until you can remove the lever that operates the clippers. That will allow the clippers to open far enough so the plastic base of the bulb can be held by the jaws of the clipper.

Jack Yates

 

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This page was last updated on February 18, 2004