bakedgoods

The spring rates for the swift R:

420 - front
392 - rear

From my understanding the Koni Yellows OTS (off the shelf) allow for springs with a maximum rate of 450-550. The advertised rate (I believe 500) is more then likely cautious as I have heard of good results with rates of 550. Additionally, an engineer from Koni stated they wouldn't run higher then 450 without re-valving (not verified read from a post on s2ki)

Please see my estimates below regarding rebound.

Assuming strut rate is 500lbs

front rebound
420 spring /500 strut = 84%
84% X 2 rotations = 1.68 rotation or 1 and 5/8ths of a turn (1.625 - rounded down to the lowest 8th)
Using this calculation the rebound would be set at approx. 96.73% of the spring rate

Rear rebound
392/500 = 78.4%
78.4% X 2 rotations = 1.568 rotations or 1 and 4/8ths of a turn (1.5- rounded down to the lowest 8th)
Using this calculation the rebound would be set at approx. 95.66% of the spring rate

I think 8ths of a turn is about as close as you can hope to be without an EDFC (doesn't exist for koni yellows and overkill for this setup)

Is this logic proper?

Slowcrash_101

Critical damping is ~70% of damping matched to the spring. This is a good general value that avoids hysteresis.

bakedgoods

This is a fun exercise. I had to look up hysteresis.

Hysteresis is defined as a lag or differential in the expected output force of a spring caused by friction. This is most evident when the output force is measured during extension and compression.

Hysteresis occurs when the damping forces are higher as the damper is decelerating compared to when it is accelerating, and will decrease the effectiveness of the shock. Hysteresis is the primary reason that a shock should be valved to be used in the middle of its adjustment range, as hysteresis is significant when you use the stiffest adjustment settings.


Front
if 1.680 rotations = 100% dampening then 70% dampening = 1.680x70% = 1.176 rotations
(A) rounded down = 1.125 = 66.96%
(B) rounded up = 1.250 = 74.40%


Rear
if 1.568 rotations = 100% dampening then 70% dampening = 1.568x70% = 1.0976 rotations
(A) rounded down = 1.000 = 63.78%
(B) rounded up = 1.125 = 71.76%

Assuming the strut rate starts at 0 (0 turns) and goes to 500lbs (2 full turns) in a linear fashion the figures above should be accurate.

If I had to guess I would use:

Front B setting (1 and 2/8th rotation)- I feel it is ok to slightly over damp the front to 74.40% as the spring rate is slightly higher in the front
Rear B Setting (1 and 1/8th rotation)- The rounded down rate of 63.78% is too far from the target goal of 70% thus I would go with rear B as it is still less then the front and closer to 70%

All in all there are a lot of unknowns. For instance, do the konis adjust in a linear fashion? Obviously, the Koni's don't start at 0lbs at 0 rotation. I suppose this is why someone would use a shock dyno especially when using a set of nice coil-overs.

User 121020

Just a note for clarity - I think this is backwards. As the piston is accelerating, the shims are moving from closed to open. The shim-to-shim friction fights the shim opening motion and causes more resultant damping force. Conversely, as the piston is decelerating, the shims are moving from open to closed. The shim-to-shim friction fights the shim closing motion, reducing the resultant damping force. Some recent dyno data I collected supports this, as well.

If I'm not mistaken, the Koni yellow adjuster is highly nonlinear (maybe this is why it's recommended to stay away from full stiff?). I don't have dyno experience with them, but looking at dyno plots, it appears they are nonlinear like many dampers. My Penskes are non linear in rebound. A set of Ohlins TTX25s (really Cane Creek bike shocks) I recently tested the crap out of are HIGHLY nonlinear... as in 1/3 of the adjuster range controlled 80% of the damping adjustment range.

bakedgoods

I have emailed koni to see if they could provide some insight. I will update when I receive a response. I appreciate everyone's help.