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      05-22-2013, 04:28 PM   #22
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Drives: 2009 135i
Join Date: Nov 2007
Location: Indianapolis

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Quote:
Originally Posted by csween86 View Post
Isn't that just basic stability/traction control, DSC or DTC which gives you a higher threshold of wheel slip and slide before it kicks in? Wouldn't an LSD divert torque to the wheel with less slip, rather than braking the wheel which isn't getting traction?
Traction control usually just means cutting engine power due to total traction level being insufficient for the power being delivered. The eLSD is taking that a step further at looking at the wheel speed difference between the left and right, and possibly steering angle and/or yaw rate of the car, then using the brakes, not the throttle plate. It's slightly more sophisticated.

Even with TC off, the eLSD remains on and will try to keep the two wheel speeds in check. TC is cutting throttle and power, eLSD is not. You can do donuts with eLSD on but not TC.

It could be very arguable what is traction control, stability control, and eLSD functionality, so you do have a fair point. I would say TC generally does not know about the vehicle beyond total vehicle speed and average drive wheel speed, then acts on engine power. Stability control is looking at yaw rate of the car, maybe suspension displacement at each corner, things like that, and using brakes at all corners to keep yaw rate within limits. ABS looks purely at wheel speeds and maybe steering angle at best and acts on all four brakes. eLSD looks at drive wheel's speeds and maybe steering angle and acts only on drive wheel brakes to try to keep the wheel speed differene within limits
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2009 BMW 135i 6MT Sport, AFE intake, Cobb AP, Apex 18x8.5+9.5, 255/275 PSS