The H&R 29583 is a set of four sport springs for the E31 generation BMW 8 Series, covering the 840Ci, 840i, 850Ci and 850i in the versions built without factory self-leveling. H&R's listed specs call for about 1.25 inches of front drop and about 1 inch at the rear, using a progressive-rate coil meant to lower the center of gravity without a harsh ride. The coils are made from 54SiCr6 spring steel and shot-peened for fatigue life, so they hold their height better than budget lowering springs of unknown steel. The lower stance also closes the fender gap that stock ride height leaves on these cars.
The reason to pay for this kit over stock springs or cheaper aftermarket drops is handling. A lower center of gravity and a firmer rate reduce body roll and sharpen turn-in on a heavy V8 or V12 coupe, which matters for canyon runs, autocross, and track days. Expect a firmer ride than stock, and pair the springs with dampers matched to the lower ride height. Before you order, confirm the car has no factory self-leveling and check the year against the fitment chart, because published model-year coverage varies between sources. Typical applications include the M60 and M62 840Ci and the M70 and M73 850Ci.
No. This kit is designed for E31 models without factory self-leveling. Cars with self-leveling use a different rear setup, so check for it before ordering.
Sources disagree on exact year coverage, and the fitment charts list different years for each body and engine. Confirm your specific car's year and configuration with the manufacturer before ordering.
This is an intermediate job that takes a separate spring on each corner. Front springs usually require removing the strut, then compressing the coil with proper spring compressors before the top mount nut comes off, so use quality compressors rather than budget units. Rear coils are typically removed by unbolting the shock and lowering the control arm to release the spring. Replace the springs in pairs on each axle, seat the rubber isolators and upper and lower perches correctly, and torque all fasteners to the manufacturer's specification. Get a wheel alignment afterward, since front strut work changes camber and toe. Plan for jack stands, a torque wrench, and a helper for the rear.
