Johnnysrx wrote:I'm interested to hear your finding with the new swaybars, as I have pretty much the same car as you with the same tires.
A long-time local friend and board member (who I met through mye28!)
Derrith came over Saturday and installed the Eibach 30mm/20mm sway bars on the f10 (vs the ///M Sport 22-24mm/14mm). They really transformed the car and it now handles like you'd expect
any generation 5 series with "///M" badging on the door-sills to handle: flat, neutral, and without drama. The ride quality was impacted minimally, with the front wheels really just feeling more communicative and steering a bit tighter and more responsive than before, which it kind of needed. It actually feels a lot more like an e39 now, to be honest. Both passengers I've had so far have immediately noted the improvement within a mile of being in the car.
Specifically, I observe the following, more measurable improvements after changing the tires and then the sway bars:
- Full-circle on/off ramps --
- before tires -- generally had to stay ~5mph under the recommended speed on the yellow signs to prevent actual slipping at the front wheels (so 15 for a familiar recommended 20 ramp)
- after tires -- could do 20 in the recommended 20, but 25 would be a bit scary
- after sway bars -- found myself doing 35 in the recommended 20 and it felt oddly safe; 35 is where my e28 starts to complain around this particular loop
- Off-camber curves --
- before tires -- SCARY...seriously the front would start slipping at surprisingly low speeds, I got in the habit of staying ~10 mph under on very curvy roads
- after tires -- Grip was no longer an issue here, but the body lean would leave me holding on to the steering wheel to maintain my driving position (no sport seats in my ///M-Sport

)
- after sway bars -- Lean is gone and I stay in my seat, and the car feels like it could go much faster than I'm actually comfortable with
- Curvy roads/spirited driving --
- before tires -- It just wasn't fun at all. Downright terrifying.
- after tires -- Again, grip was no longer an issue, but the lean and weight transfer would leave me holding onto the wheel for support and the tail would have an odd tendency to want to act like a pendulum at times. Putting down power coming out of a curve was still a bit precarious...you really needed to make sure the rear-end was fully settled out of the curve before booting it.
- after sway bars -- The rear end is really planted in all situations now and doesn't really make a fuss about itself anymore. The power feels much more controllable, especially transitioning out of curves/turns.
- Dips on one side of the road -- we have this particular issue in SF a lot with relatively deep rainwater drainage holes (covered by grilles) on the edge of the roadway, and narrow lanes means you dip into them with one tire frequently --
- before tires -- Traction control light, every time
- after tires -- No more traction control light, but dip and rebound on one side would slowly transfer to the other and cause the car to uncomfortably pitch and roll out of it from side-to-side...again with me holding onto the steering wheel for support
- after sway bars -- Car tracks straight and true regardless of the dip and the other side stays planted
Overall, I'm really glad I did the sway bar upgrade even though I generally plan to avoid doing much to this particular car. It's not only brought it in-line with how I expected the car to handle, but it's actually kind of exceeded those expectations, so pretty happy about that. The above were just noticed after a day and a half of driving it around this weekend, so I'm sure I'll be able to be more comprehensive in a month or two if anyone is interested.
Front (red is Eibach):
Rear:
