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      01-19-2017, 12:43 AM   #64

Drives: 2011 135i M Sport
Join Date: Jun 2016
Location: Australia

iTrader: (0)

Originally Posted by drwillb View Post
This is a quote from the E92 M3 Training manual, found here:

The design of the rack-and-pinion steering system is the same as the series E92. The average variable overall ratio is 12.5 and hence sports-oriented (16 in the series E92). In the M3, the steering force support is controlled by the MSS60 via the Servotronic valve. A speed dependent characteristic curve is stored in the MSS60 for this purpose. With the MDrive menu option, a second and even more sports oriented characteristic curve can be activated (see the chapter on MDrive).

So, it seems there are two different assist curves for the steering.

Muppet, is there any way for you to find out which one you sourced from the 1M? I would certainly prefer the "more sports oriented" one if given a choice. I had an 09 Z4 35i and the steering was just dead, numb, and totally disconnected unless you pushed the "sport" button. Then there was some feeling in the steering. However, I think that car had full electric PS, which would explain a lot of the numbness. Now I'm wondering If I should just stick with the current rack and hydraulics only?
I understand there is only one setting programmed in the 1M ie no other "sport" setting which effects the steering. The system is a full hydraulic set up. The voltage that is sent to the valve comes from the JBBF ecu rather than the DME in a M3 which has varying voltages for different assistance. I could find no lines of instructions which related to different settings but as stated in my previous post there are some ST_ instructions in the JBBF ecu which may enable adjustment of the level of assistance at different speeds, but I think these only apply to active steering.

I have to say I am happy with the set up at present. It has eliminated the standard 135i lightness at low speed and does transmit more road feel as you would expect from a quicker rack. I am pretty sure this would be the "sports" oriented setting as I could not see a mass marketed car having this weight of effort. Maybe a 1M owner would like to chip in.