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      12-03-2014, 08:18 AM   #27
CSBM5
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Quote:
Originally Posted by Falafel Combo View Post
Thanks for this link. I've never seen this article before. But I am seeing mostly positives here, and none of this explains my dissatisfaction with the f30, compared to the e90. Maybe #3 and #10. The rest is mostly positive improvements.



"The Morse *Measurements data confirms some *suspicions but also refutes a few impressions logged during thousands of miles of 3-series seat time. Here’s what we learned:

[1] The 328i we tested for 40,000 miles weighs 3434 pounds, while a 2007 335i owned by former Car and Driver editor-in-chief Csaba Csere scales in at 3671 pounds. (Weight and CG data came from our garage, not Morse Measurements.)

[2] The 328i has better weight distribution (49.2 percent front/50.8 rear) than its immediate predecessor (50.5/49.5), but the older 335i’s center of gravity, at 20.0 inches high, is an inch lower than the 328i’s.

[3] The 328i’s wheel rates (overall suspension stiffnesses) are 2 percent softer in front and 10 percent softer in back, which helps explain the new 3-series’s smoother ride.

[4] The 328i’s anti-roll bars are slightly larger in diameter.

[5] Roll centers, both front and rear, are an inch higher in the 328i. (Suspension geometry defines theoretical points—one in the front, one at the rear—about which the body rolls when subjected to cornering forces.) The *imagi*nary line connecting the front and rear roll centers is called the roll axis. For a given center of gravity and cornering rate, a higher roll axis (closer to the center of gravity) yields less body roll.

[6] The 328i and the 335i both roll 3.4 degrees per g during cornering. This is the net result of findings two through five.

[7] There’s significantly more braking anti-dive built into the F30’s front-suspension geometry and slightly more anti-lift designed into its rear axle. Both characteristics are advantageous to braking performance.

[8] The 328i’s outside rear wheel toes in significantly more when subjected to cornering loads. This is a stabilizing feature to induce understeer, and BMW apparently implemented it as an alternative to the 335i’s staggered (larger in back) tire sizes.

[9] The 328i’s steering is 8 percent quicker than the 335i’s and has significantly less ratio change as the steering wheel sweeps lock-to-lock. This may be attributable to an improved steering-column design with reduced universal-joint angles [see graph above].

[10] The slip angles producing cornering forces at the tire patches create what’s known as aligning torque—essentially, the tire trying to return to straight-ahead running. This aligning torque is fed back through the rack-and-pinion steering gear to the steering wheel. It’s part of the information the driver uses to learn what’s going on where the rubber meets the road. The K&C machine reported that aligning torque is 64 percent lower in the 328i than in the 335i. While the switch to electric power steering may improve mileage, it’s a bummer for Bimmer driving satisfaction."
#8 and #10 are the two biggies for those that are fanatic about driving enjoyment/autocrossing/tracking/etc, especially #10. I'm guessing as time moves on, BMW will continue to work on the EPS systems and perhaps eventually obtain levels of communication that their prior HPS systems did as you approach the peak and go over the top of the tire's tractive force/slip angle curve. The "connection" to the brain through that critical region of tire grip is where EPS systems, even on the F80, appear to be still a work-in-progress. I wouldn't be at all surprised if BMW releases s/w updates as time goes by and they learn more.

#8 is a bitch too since it's like a crutch to induce understeer by toe-ing in the rear outside tire on compression significantly. The feel to that back outside rear corner through the seat is probably one of "yuck", i.e. not precise, not well-defined. It's really the last thing you want going on for a high performance chassis.
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Current Stable:
2019 F87 M2 Competition 6MT, LBB, slicktop, exec pkg
2011.5 E90 M3 6MT Silverstone II, slicktop, Dinan/Eibach, Apex 9.5/10.5x19 with PS4S
2007 E91 328i Silver, slushbox, Eibach fr/E93 M3 rear sway bars, 219Ms
1975 CanAm 125MX2, stock, original owner