The H&R 50404 is a progressive-rate sport spring set for the 1990–1991 BMW 318i and 318is (E30) in non-cabrio form. It is a lowering coil spring kit, and the ride height is listed as lowered. Compared with stock, it gives a tighter fender gap and a lower center of gravity, and the progressive spring rate design is meant to keep ride comfort on the street. Within H&R's E30 lineup, this is the milder tier, so it suits a daily driver who wants a sportier stance and occasional track days without the firmer feel of the Super Sport or Race springs.
Owners on user forums often pair lowered E30 springs with upgraded dampers. Fitting the springs onto worn stock struts can leave the suspension riding on bump stops. The actual drop can also differ from published figures. One owner on a user forum expected about 1.25 inches at the front and reported a much larger drop at the front than at the rear. Confirm the expected height with H&R before you order, and check the body style and chassis, since this kit is for non-cabrio cars only.
No. The part is designed for non-cabrio models only, so convertibles fall outside its application. Confirm your body style before ordering.
Owners on user forums report that the actual drop can differ from published figures. One owner expected about 1.25 inches at the front and measured a much larger front drop. Expect variation, and measure your ride height before and after installation.
Owners on user forums commonly recommend checking the dampers during a spring swap. On a front Bilstein B8 with a lowering spring, one owner noted the internal bump stop may need to be shortened to avoid riding on it.
This is a moderate DIY job. Per owners on user forums, the fronts require removing the struts, and you need proper spring compressors to do it safely. Slacken the strut center nut before lifting the car. Rear springs need little or no compression, so that side is far easier. Use a floor jack and jack stands, and keep the compressed springs under control, since the stored energy is substantial. Recheck alignment after installation, because the new ride height changes camber and toe.
