Dampers

Basic Damper Operation







When the vehicle bounces the damper travels thru the compression and rebound stages. The damper as illustrated corresponds to the EDC sport damper setting because the oil transfer uses only a mechanical one-way valve.

Solenoid Controlled Dampers












The EDC system utilizes solenoid valves to change the valving in the damper to relieve the oil flow through additional valves and create a softer damping value.

The recent pre E38 EDC systems use dampers with valves mounted externally of the dampers.

The front axle twin-tube, gas pressurized dampers and rear axle single tube dampers of the 750iL both have integrated internal adjusting solenoids for EDC control. The solenoids contain two orifices for oil transfer through the piston valves.

There are three valves for oil transfer in the strut piston. The first is the main oil transfer valve. This valve is always always open. The second and third valves are controlled by the EDC solenoids. Through the two different orifices, the solenoids can vary the throughput of hydraulic oil transfer thereby regulating the damping force.

Soft Setting - In this setting the "soft" solenoid in each shock is energized allowing oil transfer through the mechanical orifice and larger diameter "soft" orifice. The soft setting provides oil transfer with the least restriction and the struts are set to the softest damping force.

Medium Setting - When the EDC control module's processing calls for the medium setting, the soft solenoid is de-energized and the "Medium" solenoid is energized so that the oil now flows through the smaller valved orifice. This restricted oil flow increases the damping force of the strut.

Hard Setting - When the EDC control module's processing requires the hard setting, the medium solenoid is switched "OFF". This closes the solenoid controlled orifices and only allows oil transfer through the main valve. The struts are now set to the maximum firmness.

This is also the failsafe setting of the EDC III system. With no power applied to the struts, the system will be in the hard setting.

EDC Special Tools

Adapter Harness EDC Shock Solenoids







P/N 90 88 6 616 041

Special adapter harness plugs into shock harness for testing purposes.

Shock Assembly Removal Socket







P/N 90 88 6 312 210

Special socket for disassembly of shock absorber with new solenoid harness.