Originally Posted by F10N47
BMW aren't very forthcoming with their technical specifications, especially regarding suspension options. My understanding of the F10 set-up is:
1. reduced (softer) spring & damper rates for models without M sport suspension
2. increased (firmer) rate and shorter springs (to reduce ride height) and increased rate dampers for models with M Sport suspension
3. reduced (softer) spring rates for VDC option, plus the facility to vary damper rates between the softer standard rate and the M Sport rate
If my understanding is correct then an M Sport model will still have firmer suspension due to higher spring rates than a VDC equipped standard set-up, even though damper rates will be the same if the firmest setting is selected on the VDC.
If anyone can shed some light on this I'd be interested to hear.
It is a big subject and agree we would like more technical data.
I think you are summing it up pretty much as it is, but it is even more complex if you are trying to determine the ride/handling balance of any particular setup, particularly when we add Adaptive Drive, which has the additional active anti-roll stabilization. At least BMW have given out technical data on the differences in performance to fixed roll bars with graphs and actual figures. Plus explained how it can change understeer and oversteer on the fly.
BMW have never been too specific of spring and damping rates, other than comments like "the M-sport suspension has a more sporty drive". Even official BMW media releases don't get near to what we really want to know. At launch, even Adaptive Drive was stated to have the 10mm lower ride height, which doesn't appear to be correct. I've never measured mine... as I've not found data to reference to.
Add in F11 rear suspension.... I personally like the F11 suspension better than the F10, as it has rear self levelling air suspension. So we get variable spring rate according to load, and that improves low speed/low load ride quality. I agree with many others who find the sport springs in many BMW models are to stiff, they are fine for high speed driving, but very knobbly at low speeds and low loads.
In my own experience with Adaptive Drive, I find the spring and damping rates are pitched just right. Enough spring rate to give the widest working envelope and damping rates which fit around the spring rate. 'Normal' is well balanced as we would expect, with 'comfort' feeling slightly under damped and 'sport' slightly over damped, but well in the range of the spring rate. I wouldn't want a stiffer spring, even in my M-sport, as it would start getting knobbly on my daily driving roads. It is not just the stiffness for me, but the frequency at which the suspension works, stiff springs raise the frequency and I find that wearing over distance.
But how we get the specifics and technical details/data of individual setups, appears impossible, only trying them can give us the real differences it seems.