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BMW 5-Series (G30) Forum 2017+ BMW 5 Series (G30) General Discussions Torsional rigidity

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      01-12-2018, 03:15 PM   #1
AP
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Torsional rigidity

With reference to the following article, out of curiosity was wondering what the torsional rigidity of the G30 is. BMW state its better than the F10 (which I believe was pretty high anyway). never seen a figure if one even exists.
Anyone happen to know? as I say just curious.


http://youwheel.com/home/2016/06/20/...ehensive-list/
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      02-10-2019, 12:35 PM   #2
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Since G30 and G20 are sharing same CLAR platform, percentage of torsional rigidity should be inline with G20.

For Comparison:

E46 - 18,000 Nm/deg
E90 - 22,500 Nm/deg
F30 - 29,300 Nm/deg
G20 - 36,625 Nm/deg (based on 25% more than predecessor, could be higher in body stiffness in certain area if 50% is applied)

E39 - 24,000 Nm/deg
E60 - 24,200 Nm/deg
F10 - 30,200 Nm/deg
G30 - 37,750 Nm/deg (based on 25% more than predecessor)

As we can see there is a steady increase in 3er since E46 with average of 25% - 30% torsional rigidity improvement. Except between E39 to E60, there should be an average of 25% improvement on 5er.
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      02-10-2019, 02:31 PM   #3
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Thanks . That's impressive
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      02-16-2019, 05:58 PM   #4
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Quote:
Originally Posted by AP View Post
Thanks . That's impressive
on the M340i especially, not necessarily 330i. The same way the F30 335i MPerformance was stiffer overall than the 328i. Some calculations include the suspension effect. Any F30 with lower stance better springs and better sway bars was better than the same car stock. Bars especially make a difference. But if you consider that the F30 top settings exceeded the Pagani Zonda of 2009, then it becomes clear that the true difference is in setup, ride height and track width. A 335i with 275 rear tyres would like excel a G20 with a 225 rear for example... So the better wuestion is which G20, too much dilution..
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      02-18-2019, 07:30 PM   #5
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Quote:
Originally Posted by Musashi View Post
on the M340i especially, not necessarily 330i. The same way the F30 335i MPerformance was stiffer overall than the 328i. Some calculations include the suspension effect. Any F30 with lower stance better springs and better sway bars was better than the same car stock. Bars especially make a difference. But if you consider that the F30 top settings exceeded the Pagani Zonda of 2009, then it becomes clear that the true difference is in setup, ride height and track width. A 335i with 275 rear tyres would like excel a G20 with a 225 rear for example... So the better wuestion is which G20, too much dilution..
The suspension does not figure into the body-in-white bending and torsional rigidity measurements. They are done on the bare structure (or with added structural components that effect the stiffness). The only additional components that come into play would be additional bracing such as the M2/M3/M4/M5/M6 employ (recall the video where the M-engineering head discussed how much the added bracing and the solidly bolted rear subframe on the F80 increased torsional stiffness versus the plain F30 structure for example - it was a huge increase as I recall). The other factors that come into play are whether there is a sunroof and/or fold-down rear seats (both reduce structure stiffness).

The other figure that isn't mentioned is the mass of the body-in-white. It's only when you combine the mass with the stiffness values that you can obtain the natural frequency of the structure.
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