Urge

When considering rear spring rate options for the DFV, I ran some calculations a few months ago and you could choose to run a 7" or 6" Swift spring with a helper/assist spring in order to get the static piston position into the middle of the range instead of next to the bump stop. The shorter main spring makes room for the helper and there wouldn't be any spring bind because the Swifts can compress far enough. It would likely be lighter than the included 8" setup. That's assuming you have enough spring perch adjustment in the "raise ride height" direction (or are going up in spring rate, but that's another topic).

That said, I have to wonder about Ohlins' choice to set up the shock to run that far compressed at static height because it sounds very odd, and yet I've never seen anything but glowing reviews of their ride and performance. Maybe that was on purpose? Perhaps the included bump stops have wide, progressive compression and were actually intended to be part of the overall net spring rate? Anyone have a pic of them? More importantly, does anyone have a pic of them with the car on the ground? Gernby took measurements but installed them with the dust covers on, so we can't actually confirm compression travel before bump stop engagement to make sure he calculated everything correctly.
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Interesting, would love to see the calculation and possible drawing.

Wouldn't you want the piston closer to the bottom of the shock when static vs the middle? Thus you have more travel/compression to play with? You don't really need more rebound when static or unloaded? You can adjust the ride height with out adjust pre load or moving the piston to the middle of the shock when static.

Slomaro, how the DFVs holding up? This is one of my favorite review and just wanted to check in.

thomsbrain

I used the term "static" to mean the car is sitting on flat ground and the suspension is loaded. Hopefully that's the right way to say it. I was assuming (perhaps incorrectly) that we would would want the damper in the middle of its travel range in this situation (equal available compression and rebound travel). As for whether it would be better to have more compression than rebound travel, or vice versa, I don't have info on that but would love to learn.

I just picked up a set of DFVs (sorry I didn't go through Urge as a forum sponsor, but I bought mine custom-valved and dynoed from my local builder all in one process). I have them valved for stiffer rear springs, so I will take copious measurements prior to assembly and ordering springs. Then I will see if there indeed is room in the adjustments to run a shorter/stiffer Swift spring and if a helper spring would be part of doing that. I'll post measurements and calculations to this forum once I get stuff figured out and have dummy-checked myself. I don't want anyone else to be led astray by my experimenting. If stuff checks out, I will send you my Excel sheet for predicting piston location/spring travel at different spring rates on the S2000.