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      11-28-2013, 07:01 PM   #15

Drives: F80 M3, 228i THP, E46 ZHP
Join Date: May 2009
Location: Ann Arbor, MI

iTrader: (0)

Originally Posted by DVC View Post
@Racer20, what are your thoughts on the claims that a faster lap time can be recorded in an adjustable suspension's Comfort mode than Sport mode? (I've read this claim a few times with various cars - not just BMWs). It seems counter intuitive that a softer suspension (with more body pitch/roll) could maintain better grip and speed...
Here's the next chapter:

First, some backgroud

Stiffer and softer aren't really that meaningful when you're talking about a whole suspension system. The reason stiffer is better is that a pair of tires (left and right or front and rear) works better when the weight on them is equal. When you transfer weight between the two, as in body roll, brake dive, or squat, you ALWAYS sacrifice grip.

All else equal, a stiffer suspension resists weight transfer better than a softer one, and less weight transfer means high total traction capacity between all 4 tires.

However, "all else equal" is rarely the case. Some factors that might cause stiffer to be slower:
  • Not enough compliance to maintain grip on a bumpy track
  • Poor front to rear balance (poor steering response or feedback, unbalanced roll, excessive under/oversteer)
  • Non linear, jerky suspension motion or jacking
  • Too responsive for the driver skill, not confidence inspiring. Stiffer suspension means there is less body motion to clue the driver in as to what's going on, and also requires faster reaction times and more precise inputs.

How this relates to the E92 M3:

My understanding is that "sport mode" in an E92 M3 is a fixed steady state setting with no adaptive control. I was surprised when I read this, because you give up the main benefit of EDC when you do this, and this will almost NEVER result in an optimum solution. I can see several of the above scenarios being the case if the shocks are being used in this manner.

The competition package supposedly uses adaptive control for sport mode, which, in theory, should be much better, but I haven't really looked into lap times. The E92 is on my shopping list for my next car, and I would not buy one without ZCP because IMO, the base EDC sport mode is useless. (I haven't driven it in sport, but that's my conclusion based on what I know and the reviews I've read).

Further, keep in mind the Nurburgring is a very unique place, and typically requires quite a bit more body control than our tracks here. A car that is optimized for the 'Ring may be too much for your average driver on an average track here. Plus, tuning on the ring isn't really about lap times, it's about making sure the car handles the various individual corners, bumps, and pavement transitions well.