theCARhack

Almost all European cars come across the ocean with a bit of a lift thanks the the different government regulations between the two continents. Be it bumper height regulations or headlamp positioning, BMWs, Mercedes, VW and Audis all tend to be raised up about 20 mm to 40 mm. A typicle sport spring from Eibach or H&R lowers the ride height by at least that much and then some-- 1 to 2 inches total.

The already gorgeous Laguna Seca Blue M3 above is a good example of how moderate lowering can significantly improve the overal stance of a car.

The key to a proper spring swap is in the hundreds of little details. For example, we clean all the mating surfaces once the old springs/struts are removed. If dirt or grit were allowed to get between the springs and spring pads, or the struts and the strut towers, the suspension could nott be properly aligned and tightened. While this can be done at home by an experienced do-it yourselfer, it is an extremely dangerous proposition if you don't have the right tools (sturdy lift, spring compressors, offset wrenches, etc).

Also, the car will need an alignment, which again is nearly impossible for the home mechanic to do properly without the right equipment. The amount of adjustment required after sport springs have been installed depends upon the geometry of the specific suspension. Toe tends to change the most, along with camber and then castor to a lessor degree.

Bottom Line:
A sport spring upgrade that lowers the ride height is a inexpensive way to upgrade the handling and looks of your car. It is a straight forward job that is best left to a shop you trust. The springs are inexpensive , typically running between $200 and $400. And the shop time is minimal 4 hours on the low side but up to 8 hours on more complex suspensions.

Check out the opinion of the owner of the above pictured M3 here: http://www.m3forum.net/m3forum/showthread.php?t=156405