Quote:
Originally Posted by radioranger
Well I was going to go a bit more radical, and wondered if anybody had coments on lowering just the rear a bit, since it should be cheaper and not mess up the alignment too much , just go down to full load height and of course extend the factory spoiler down and around the corner of the undertray area.
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Lowering the rear end is probably the worst thing you could do: It just makes the underbody a trap for air, acting essentially like a boogie board that kids use to skim along the shallow water at the beach. If you're going to lower anywhere, lower the front of the vehicle, adding some rake so the vehicle wedges under more air (slightly negative angle of attack) and gets some downforce rather than lift. Go with the front air dam, too, then undertray and/or wheel fairings.
On BMW forums is an ongoing debate about cutting one coil or so off the front springs, giving the car a bit of rake. Some say, only go with expensive aftermarket springs. Others, who've actually tried it, say cutting ~1-1.5 coils off the bottom of the front springs lowers the front by ~1-1.5" , stiffens the spring rate a bit, yet gives essentially the same ride quality. That said, don't cut springs with a torch, which ruins the metal temper. Keep them cool, cut with cutoff wheel or Dremel disk, lubricating and cooling the cut with cutting fluid or oil. (Wrap the spring just above the cut with a wet rag, so the metal does not heat much.) Obviously, first check the spring perch to be sure it will mate with the diameter and pitch of the spring
after it's cut. If you do this, proceed at your own risk, consult an engineer, and don't sue me.