Servotronic: Variable assist by bypass or....??

[Cacatfish]

Im tryin to come to terms on te principle of Servotronic steerin on e34s.
Is it some kind of bypass or just an adjustable orifice closin under increased speeds?
Any info appreciated,
Colin

[George M]

a pulse generator/speed sensor in the diff provides real time vehicle speed to a small
variable resistor that changes current to a servo/stepper solenoid on the bottom of the steering box that controls orifice size/volumetric flowrate/pressure and therefore amount of assist. The servotronic control modules are prone to fail after 100k and since I never liked the calibration on mine anyway, I deleted mine and dail in a dual effort steering setting via two finite resistors...lighter effort for cruising and a performance higher effort setting for spirited driving which is how I drive most of the time :-) The more E-32's I drive, the more I realize how much I like my non-speed proportional set up which is similar to most E-34's but the exception I can tune the effort to my liking.
Most servotronic steering was overassisted and too variable from park to highway speed.
HTH,
George