Thread: Coilover FACTS.
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Old 08-27-2010, 10:22 PM   #11
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Drives: Camaro Justice
Join Date: Jun 2007
Location: Virginia
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Think of the coil spring as being perfectly cylindrical with the winds perfectly spaced at 25mm with 2mm of preload. They general are not, but for sake of discssion we'll say they are. 2mm of preload is Pedders specification for the Xa and Supercar front coilover. To raise the car from the mid-point on the coilover by spring perch 20mm you would need to screw the spring perch up 20mm. The coil has no where to go because it is captured between the upper spring seat and the lower spring seat. So the coil spacing will change as you raise the car. The inverse is also true until the coil actually become loose when a at full droop on a lift. Not only does this change how the coil reacts, it changes the jounce travel the amount of travel in the damper until the bumpstop is fully compressed. In the previous generation eXtreme coilover we made, we used helper spring to offset this. That creates different issues and there is no need to over complicate this.

Going back to the 2mm of preload specified in Pedders Xa and Supercar Coilovers. We set the preload at 2mm. The coil spacing is exactly where we want it. There is roughly 3" of adjustment in the front of a Pedders Camaro coilover or 75mm. If we adjusted height by moving the spring perch we would not come close to maintaining the 2mm of coil preload once we move up or down 2 or 3mm. By setting the coil preload at 2mm we also set the jounce travel. No matter how high or how low you set your Camaro with a Pedders coilover the travel to full compression of the bumpstop remains the same and so does the ride quality.

A damper / shock does not carry load. The spring carries load. The center bushing in the Camaro was designed ONLY to mount a damper. The surrounding spring perch was designed to carry load. The load bearing rear mounting points in a 5th Gen Camaro are the upper and lower spring perches / seats and not the shock mount.
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