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      10-19-2012, 04:29 AM   #2
ovekvam
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Norway
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Drives: 2021 Galvanic Gold i3S
Join Date: Jun 2012
Location: Bryne, Norway

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The need for a limited slip differential depends a lot on load distribution. As long as both driven wheels are equally loaded, there will not be any problems with one wheel spinning. The problem is that the inside wheel is usually unloaded in corners, and can not get much power down. The stiffer the suspension is, the more unloaded the wheel gets.

To get more power down, you can soften the suspension (swaybar) on the driven axle, and stiffen the other end of the car. That will reduce inside wheelspin significantly, but will usually also upset the balance of the car. In a RWD with soft rear suspension, you will get plenty of understeer that has to be compensated in other ways.

I have always been a big fan of limited slip differentials, and that is usually the first modification I do to my cars. They need a stiffer rear swaybar and an LSD. With the F20, I have found that it probably isn't necessary, since the e-diff system is working surprisingly well, and the car is well balanced.

I am a big fan of driving sideways in slippery conditions, and the F20 is well suited for the purpose, even the 116i. You can drift it nicely around an ice track. I have however found that drifting in summer conditions is very difficult. There is not enough power compared to grip, and the e-diff can not cope with the high loads involved. The turbo lag is also making it difficult to steer with the throttle.

Driving on the limit with the car in balance works well. The car can be set up sideways under braking, and you can go very early on the throttle out of corners. When trying to drive good lap times, I do not miss the LSD. I also find that the F20 is cornering more on rails than older BMWs. While you used to balance them with the throttle, you now control the car a lot more with the steering wheel. The balance does not change much when you alternate between braking and full power in corners. It stays well balanced and just changes the velocity. Almost like a computer game. And this is with DSC completely off.

There is no way to disable the e-diff in the F20 without doing modifications to it.
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