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Old 12-31-2012, 10:21 AM
Brian Martin,Freelance adviser
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Originally Posted by MARTINSR View Post
You are so right Tim, why redesign what they have provided? Moving the rack or changing it's body length (distance between the inner tie rod end pivots) is moving it out of the arch and pivot points of the control arm and will provide bump steer.
Moving the rack doesn't effect ackermann at all. The only thing that effects it is the location of the tie rod end pivot point in relation to the knuckle or spindle pivot point in relation to the center of the rear axle.

This is a good example of how moving the rack or puttinging the wrong one in effects things.

If the racks tie rods are not matching the control arm they make a different arch. This different arch in effect "lengthens" and "shortens" the rod. Look at the drawing, when the wheel goes up the arch of the end of the tie rod goes in, turning that wheel in! When the wheel goes down, it's pivot is out further, effectively "lengthening" it turning the wheel out!

The control arm pivots and thus arch has to match.

By the way, where I said it is turning the wheel in or out in my description, this would of course depend on where the rack was, ahead or behind of the wheel! So "in" when the wheel goes up, would be "out" if the rack were behind the wheels and "in" if it were in front of the wheels".

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