servotronic help!

[tim s]

my 1995 540i/a's windows sticker claims i have "Engine-speed sensitive variable assist power steering".
how should i be able to tell if the servo-tronic is working?
i have the play in the center of the steering wheel. i already tightened the nut under the dash. is there anything i can do with the servo-tronics to change the center play feel in the steering wheel?
thanks
tim s.

[George M]

yes...you can introduce an in-line resistor between the servotronic control module and servo on the bottom of the steering box to firm up your steering effort. Servotronic cars are known to be overassisted from the factory and any worn steering components...or lack of proper steering box adjustment...you have a V8 car so not easy to adjust the steering box....will introduce a greater sense of looseness. The servotronic box itself may be losing its calibration as well and defaulting to a low or more assisted effort.
If you want to take a deeper dive I can provide more information.
George

[tim s]

can i adjust the box from the top or do i need to get to it from below?
thanks
tim

[shogun]

is a (or his) 'personal' set-up of the servotronic function. He can adjust it (the required power). Nice invention George.

As you know it is a speed dependent set up, not depending on the RPM of the engine.

If you want to make a try, you can just unplug the 2 connectors from the servotronic module and the steering is always very hard. Really no recommendable.
Or you just plug the 2 (1 male, 1 female plug) together and bypass the control unit, then the servo is always on full support. This is however only intended for emergency situations when the module is out of order.

I think in your case it has nothing to do with the servo but with the play of the steering. But I understand that you already have adjusted the nut at the steering box, which is basically there for this purpose. Maybe you tighten it up a bit more, but be careful.
Also have a look at the other links in the front suspension.

[George M]

Hi Erich. I have played enough with servotronic to know it is a bit ill conceived...an early effort by BMW. They in fact superceded the early module design replete with overassisted pressure versus speed curve and tendency to fail. The new design is reflected on the ETK as a later servotronic module which requires an additional pricey harness adapter. No thanks. I like the linear feel of the E-34's non servotronic steering with perhaps a bit more effort dialed in for better road feel...so decided to go that route by simply keeping the servo orifice size uniform by a single...actually a couple of different resistance levels...typ. and highway available via flip of a toggle switch under the dash and eliminate the problematic control module. Tim what I would do in your case first is replace all steering components in the front of your car with over 100k miles if your budget will tolerate it.
Second, I would adjust your steering box. This as mentioned is not easy with a V8 car. Believe there is good info in the archive of this board however and it can be performed with patience and/or a home brew crow foot wrench...can probably do it without with some contorsion :-) Agree with Erich that likely your issue is hardware related but the servotronic I have no doubt is a contributing factor to your sense of looseness...as it is on all early to mid 90's BMW's so equipped. Final tip is don't make the mistake of overtightening the 32mm nut under the dash and/or steering box to compensate for other system issues.
HTH,
George

[tim s]

the center link, tie-rods, & idle arm. i did tighten the bolt under the dash to remove the knocking noise. i did not adjust the box yet. i might try that though.
do i adjust the box from the top or the bottom of the car?
thanks.
tim s.

[George M]

you have only replaced about half the front suspension that needs it likely to tighten it up.
The box on a V8 car is adjusted from below...not for the faint hearted :-)...to get it set correctly that is.
George

[tim s]

tim s.

[George M]

how about your lower control arms? Weak dampers will also contribute to a general sense of looseness. That's the problem with piece mealing a rebuild...always another component to second guess.
George

[tim s]

mech. told me that my 540i/a has a very tight front end after he did the alignment.
thanks
tim s.