Car owners can save nearly half the cost of a professional wheel alignment with a few simple tools and materials. Precision is crucial, however, and a set of turntables is mandatory. The home auto mechanic has two options for do-it-yourself turntables. The cheap version can be assembled quickly, but might not work for more than one alignment. A more durable solution can be easily built and stored for future use.
Turntables are used in auto wheel alignment and are like coasters that go under a car's tires so they can be pivoted into proper alignment with little friction between the tire and the ground. The wheel's toe and camber settings are precisely adjusted in 1/32-inch to 1/64-inch increments, making it necessary for the home mechanic to have complete control over the tire position. Wheel alignment turntables are used in pairs and are necessary to prevent the suspension from binding during a wheel alignment.
Whether you are doing a 2- or 4-wheel alignment, you have two choices for making an affordable set of turntables. A turntable is a "sandwich" made of two plates with a layer of grease between them. A single "sandwich" goes under one tire. Cardboard turntables can be used for one or two alignments and thrown away. Aluminum turntables are used by novice race teams and can be easily stored for repeated use. Either version consists of two 18-inch squares with a layer of grease between them. Sheets of PTFE are recommended for metal turntables and can be glued into place.
For additional accuracy and durability, use 1/4-inch plates of aluminum and 3/8-inch fine thread nuts. Square nuts are easier to work with, but hexagonal nuts will also work. Mill a slot 1/8-inch deep and 2 1/2-inches long. On the other sheet, mill a counter-sunk hole for a flat-head socket cap bolt to secure the two places together.
Between the two sheets, place a large diameter (4- to 6-inch) captive ball bearing capable of withstanding a 3,000- to 5,000-lb load. Captive ball bearings can be found in the Grainger's catalog, the most popular source for home and amateur race care mechanics.
With a drop or two of red Loctite on the threads, bolt the two plates together. Drill 1/4-inch holes through the set and insert locking pins. This will keep the turntable centered and intact when the car is rolled into place for the amateur auto mechanic's home wheel alignment system.
