[BMERDOC]

Per Rob's request:

I'll try to make this simple. Thrust angle is the relationship between the rear axle and the centerline of the chassis. As I had stated before, Thrust should be zero. If the centerline of the axle is 90* to the centerline of the chassis it will be zero. Just like the front toe, toe out is negative and toe in is positive. If the thrust angle points to the left of the chassis centerline the thrust angle is negative, to the right, positive. This angle is the average of the two rear toe angles which is not to be confused with total toe which is, well, the sum of the two toe angles. If the thrust angle is negative the truck will want to rear steer to the left causing the truck to want to go right. You would have to add constant left hand input causing the "dog tracking" look. Of course, the opposite would be true if the thrust angle were positive.

Camber can have an effect on tracking too. No matter wether its front or rear. Lets stick with rear camber. A vehicle will tend to steer toward the more vertical or positive cambered tire. Lets try a small quiz...if my left rear camber is 0* and my right rear is negative .75* which way would the rear of the car wanna steer?....
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If you said left then you are correct. It would want to rear steer left and you would have to steer left to cancel it out. Both camber angles must closely match so as to not cause a "pull" or "drift".

Caster has NO affect on the rear axle...unless, in the off chance, you have a four wheel steer car. If that was the case it would closely follow the rules of front caster. Although I won't go into 4W steer it did remind me of a good point.

Rear angles have a greater effect on how a vehicle tracks. Anyone who has driven a forklift knows they can be very twitchy.