1942 - 1947 Chevrolet Shop Manual



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	constantly in mind to gain a full and true understanding of this cleverly designed mechanism. In order to correct any wrong adjustment, it is necessary to realize what effect a change in one element of the mechanism may have on the operation of the other parts. TOE-IN Toe-in is the amount in fractions of an inch that the wheels toe-in, that is, the distance between the wheels at the front "A," is less than it is at the rear "B," Fig. 34.
		Fig. 35—Steering Geometry The accuracy of the steering geometry is governed by the condition of the steering arms. For example, suppose a steering arm has been bent by bumping against a curb in such a way as to cause the right wheel to toe-in excessively when the car was turned around a corner. This tire would drag, causing rapid wear of that tire. The condition accounts for the cars and trucks we see once in a while that wear out one front tire twice as fast as the other, although, by usual tests, it is perfectly set for straight ahead driving.


	Fig. 34—Toe-In Cambering the wheels out at the top makes it necessary to draw them in at the front. Toe-in is a necessity growing out of camber and directly related to it. It might seem that since the wheels are headed inward toward the center of the road, while actually traveling a parallel course, there must be a constant grinding of their surfaces on the road surface. It would appear that they are being held apart constantly by the axle, against their tendency to roll outward to the same point. As a matter of fact, it is to avoid this tire-wearing surface grind that toe-in is employed. Just as the purpose of camber is to give the wheel a setting so it will be in nearly a balanced free-running position as possible, so with toe-in, the purpose is to set the wheel in a position to reduce to a minimum the road friction on the tire. STEERING GEOMETRY Steering geometry is the mechanics of keeping the front wheels in proper relative alignment as the wheels are turned left or right, Fig. 35. The front wheels, when the truck is making a turn, are not on the same radius line, drawn from the center around which the truck is turning, and because of this, it is necessary for the front wheels to assume a toed-out position when rounding curves. This position is governed by the angle of the steering arms.
		Fig. 36—Toe-Out on Curves
		The wheel of any vehicle, if properly set on the curves, will be at a right angle to the radius line from the center or point around which the vehicle is turning. Fig. 36 is a diagram of a truck making a left turn. The right wheel is set at an angle of twenty degrees—the angle being exaggerated to bring out the principles more clearly. A line "A" drawn through the rear axle and both rear wheels and a line "B" drawn through the spindle of the right wheel meet at "D," which is the center around which the car is turning. Therefore, the left or