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Old Thu, Jul-12-2018, 12:42:25 PM   #13
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Default Re: MK20 ABS unit differences

Originally Posted by Volke View Post
There's nothing you can really do on the MK20 currently. The issue is that DSC uses the position and rotation speed readings from the steering column rotation sensor to calculate the angle of the front wheels based on a known steering ratio. It compares this information against the readings from the yaw sensor to determine if the car is in control or not. When you change to a faster rack, the wheel angle is greater than the DSC unit expects it to be, and the car experiences greater lateral acceleration than expected, so DSC kicks in.

On the MK60, you can change to the ZCP steering setting (14.5:1) or use NCS Expert/Dummy to fake a 12.8:1 setting. This minimizes the interference, but DSC will never work as intended with a 13.7:1 rack until someone finds a way to either flash the DSC unit and change the steering ratio, or scale up the output of the column sensor to trick the DSC unit by either modifying the column sensor directly or intercepting the CAN signal with a dual CAN.

Someone on this forum is working on a dual CAN, but it will be a while before it's ready.
The yellow tag ("ZHP") rack is 14.5:1 when installed in the M3 due to the different geometry-- the ZCP setting on the MK60 is pretty spot on for it. Terra did the calculation a while back.

Current Cars: 2005 IR/IR M3, 2001 LMB/blk M5,04 M3 wagon, 2017 i3
Past cars: 04 M3, 03 530i, 96 M3, S50B32 e36 M3 CM race car
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