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      12-27-2020, 12:32 AM   #23
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Drives: E92 328i 6MT
Join Date: May 2020
Location: Bay Area

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2007 BMW 328i  [0.00]
Originally Posted by N8N View Post
This is all new to me... the way I'm used to seeing this effect done is with a progressive rate spring where either the spring is wound, or two separate springs are used (usually in a coilover setup), where at ride high the "soft" section is either at or near coil bind and then the 2-3 coils of the stiff spring take over. Then at droop, the soft spring keeps the springs from unseating and ruining everything.
From what I asked my suspension expert, he said the while the springs are progressive, they are quite similar to linear springs. In the future, I will most likely also upgrade to Swifts

Here is what he said

with the progressive springs, these are really soft in the beginning stroke of the spring and "progressively" get stiffer the more the spring is compressed. The problem with this is, as the "spring rate" depends on how much the spring is compressed, the amount of spring stroke left at the "lower rate" is very minimal and is quickly taken up by bumps, especially seeing as how around 50-60mm of stroke is already gone by default due to the weight of your vehicle. Unfortunately, spring fitments/lengths are "generic" and are not vehicle specific (i.e they don't take into account the weight of the vehicle they are being installed on. Lowering spring kits being the exception of course)

taken at the max rate, those spring rates are actually still on the soft side though (4.5K/10K), but as the range in rate in these springs is very narrow, taking into consideration the above, they're not really progressive at all. For most of the time, they would be the same as 4.5K/10K linear springs.

Hopefully this is helpful, I inquired him about tuning my kw v3 rebound/compression. One thing I will have to say is that my car is quite low already at 13 in the front. I never hit my bumpstops.
2007 E92 328i 6MT | KW V3 | 3SI | Style 219M | Headers