[quote flu]Well , I guess for the M5, they put back in a real steering rack…So maybe it’s fine.[/quote]Actually it is a real steering rack. The power assist is now done with an electric motor as opposed to a power steering pump. Of course with the way that BMW has now done the electronics on this, ‘disabling’ the electronic steering will prevent the car from starting (or even having a sensor problem on the power assist will prevent car from starting – Simpson moment doh!) – kind of dumb, since the vehicle is still able to be steered w/o power assist.. they just did not put in a reasonable failsafe mode.
As for the problem with the steering, I think that BMW needs to work on their power assist profiles. The Electric motor is used instead of a standard power steering pump so that they can vary the ‘power assist’. What is interesting about power steering systems, is that some amount of ‘play’ in the steering system is required for them to function (to sense that the driver is applying torque in a direction). With old fashioned hydraulic systems, it was just enough motion to open a spool valve. On Saginaw systems, there is a torque beam that is used to transfer torque through the spool valve, and if enough torque is given to deform steering.. opens the spool valve. These systems could be ‘tuned’ by opening up the power steering units and changing the torque beam. Unfortunately most manufacturers tended to set the Sanginaws up with a very weak beam, giving almost no road feel.
— sorry, got a little OT here on steering. Been wrenching around w/ cars too much of my life.
