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Spring Perch


If I take the spring perch and raise it all the way up, the car comes way off the ground to like 6+ inches and the spring deflection goes to like 4.06 of 4.33. But when you raise the spring perch aren't you extending the spring?

No, if you raise the car you are preloading (compressing) the spring. The chassis goes up, and the spring compresses. 4.06 of 4.33 means you'll have 0.27 of spring travel left! That spring is for sure binding on track! But by too much as your splitter will be way high.

It just seemed weird how lifting the car compresses the spring. And opposite when lowering. A lot of people were seeing the same thing and getting confused by it.

So, you aren't raising the spring perch, you are lowering it. The number is how far away the upper perch is away from the sprung portion of the frame. When you lower the perch, it pushes up on the body of the car and down on the spring, compressing it more (increasing deflection) and raising the ride height. As far as I know, it's the same for the front and rear.

When we raise the spring perch, we must be raising it from the bottom of the spring bucket, to get the spring to compress and lift the car at the same time. I wonder how it works with the rear springs since we raise and lower the perch there from the TOP of the spring. And the bottom of the spring is sitting on the truck arm.

Proper steps are to either keep the front ARB neutralized or disconnect it entirely - disconnecting is easier to keep control of. Then you'll be free to adjust perch heights to get your cross weight percentage and ride heights where you want them. Once set, you can reset the front ARB to where you want it, but if it has some preload you might have to make some small spring perch adjustments again. Beware how much spring deflections have changed as it will impact how much the front end can travel, as this affects handling.

Changing camber will always change ride heights. Always disconnect the front sway bar linkage when you enter the garage to make any adjustments to avoid running into the problem you mentioned. The common rule is more positive camber increases ride height, more negative camber decreases ride height.

When setting camber, you want the maximum lateral force production, good consistency through a run and not burn off your tires. Even temps will probably work for only two of those I mentioned.

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