[TXBDan]

My 30e's suspension is a little soft so I was wondering what size sway bars the different models have. I looked them up on realoem and summarized here:

Edit: earlier 30iXs show a rear bar. Everyone should use realoem to dig deeper for their own situations.

Thoughts:

• Because of the additional weight, the x30e gets the same swaybars as an s30i with Sport package.
• Interesting that the AWD 30is don't have rear sway bars, but the RWDs do.
• x30e and 30i Sports have same dimension FSB, but the PN is different. I wonder if the geometry is different, but I can't imagine why that'd be. If it is then that might rule out the M40 front bar for a 30e.
• Looking at some rough calculators, the M40 rear bar is a little over twice as stiff as the Sport rear bar.

Might be some nice OEM+ upgrades here for lower level X3s. The sway bars are like $220-250 each.

[prototyp]

Good find... subscribed for armchair and practical convos about suspension and spring rates. (M40i is too stiff for less-than-perfect roads, I have some theories but no means to try them out)

[sinbad4]

Originally Posted by prototyp

Good find... subscribed for armchair and practical convos about suspension and spring rates. (M40i is too stiff for less-than-perfect roads, I have some theories but no means to try them out)

Do you have the adjustable dampers? I am pleased with the M40i with adjustable dampers. 21" RunFlats don't help.. but still not bad. I will replace with non run-flats when these wear out.

[335dFan]

I don't find the 2021 X3 M40i all that stiff, but I am coming from a highly modified suspension on a 335d. Plus I purposely ordered 19" wheels with aspect ratio 50 tires. But so far I have found the cushiness quite to the liking of my wife who did not like riding in the 335d, and it had only aspect ratio 40 tires in the Michelin Comp 4s. But when I want to tighten the X3 down, it just goes in Sport or Adaptive mode and I am good for the twisties.

[prototyp]

Originally Posted by sinbad4

Do you have the adjustable dampers? I am pleased with the M40i with adjustable dampers. 21" RunFlats don't help.. but still not bad. I will replace with non run-flats when these wear out.

Yea, full Adaptive, 20" RFT... TBF the ride's fine everywhere but in our county. Not sure what's up but somehow Alameda County's roads are like billiard tables and ours in Contra Costa are crap; we seem to have either busted up pavement, rippling pavement, heaves from tree roots, or all the above. The M40's roll stiffness combined with the sporty spring rates combined with the runflat Summer Brickstones makes for a constant nervous jostling even on the straight-ahead. It gets fatiguing really quickly. (Railing a - smoother - back road all this stiffness together is fantastic, but that's a small fraction of my drive time.)

First order of attack will be non-rft, but I'm on the fence whether to go square and taller sidewalls, or hope that a mellower tire (Conti DWS06+) in oe sizes will chill things out a bit.

Originally Posted by TXBDan

• Looking at some rough calculators, the M40 rear bar is a little over twice as stiff as the Sport rear bar.

Curious what the wheel spring rates are (famously difficult/impossible to find... not listed at RealOEM even)