Setting Bump Steer Height & Shims available...

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The advantage of setting bump steer from the point of having the lower control arms parallel with the ground, is any change in bump or droop will generally result in toe in. Far better than toe out, as the car will remain more stable in its direction when moving. The only reason to have toe out, is on the inside wheel/tire when racing, which will aid in turn in on some cars. Or, when running for high speed and some negative camber is employed, as it reduces front tire scrub.