AST 5100 Series Coilovers | BMW 3 Series E30 (85-91) (ACU-B1501S)The 5100 Series shock absorbers for the 1985 1991 BMW 3 Series 325i (E30) utilize inverted upside down technology. The inverted design is race proven technology and produces an extremely strong damper, providing better suspension geometry under heavy lateral and braking loads as seen in a road and track environment. The 5100 Series shock absorbers give your car a better performance than the standard twin tube design. With the 5100 Series suspension