FF2Skip

Pete, don't know the answer to your question, but I learned a little more by trying to understand the difference between the two.

Some of the above info was found at circletrack.com via a Google search.

PedalFaster

Can you elaborate? The x-axis is labeled with "teststroke (mm)", which implies that it measures shaft travel, not shaft velocity. Now, if all of the different shaft travels were measured over identical time periods, then it would follow that the x-axis would map to shaft velocity / high or low speed damping, but if not I don't quite follow.

FF2Skip

^ I should have time to call True Choice tomorrow to help clarify. Reading the few posts here, I have a better sense of the kind of information I'll be requesting. I'm more like Cole Trickle(much better looking though ) early in "Days of Thunder." They put me in a car, and I could drive. I am learning though.

3312DC

Those tires are staggarded special, and matched perfect. She will hold.

jyeung528

interesting

there seems to be many places/people across the US that can custom valve koni yellows...

i know some people valved them to "custom" specs...would any koni valving place custome valve to these "custom" specs? or do only specific koni valvers have these specs?

glagola1

Word... please elaborate 'cause I don't see how mm can equal a value that represents time X distance.

FF2Skip

I did talk to Phil today. I asked that if he had time to look in on this thread and comment accordingly. I thought about trying to relay info, but feared screwing it up.

Windscreen

To understand all this, you need to first understand how a shock dyno works. Most dynos, outside the large OEMs, use an electric motor which spins a crank. The crank has an offset pin that is attached to either a connecting rod (just like the rod and crankshaft arrangement in an engine, known as a crank and slider mechanism), or to a cross head/yoke as in a Scotch yoke. Check the wikipedia for a better explanation of Scotch yoke vs. crank and slider

Those plots are known as force-displacement plots. They represent the most fundamental level of data that a shock dyno generates: force is recorded over the stroke (displacement) of the shock. The f-d plot is mostly useful to look for cavitation or other non-linearities (often due to slow response of the valving or lack of bleed area as the shock reverses direction).

These particular plots I don't see as very useful since the scaling on X and scaling and units on Y are not labeled. Nor do we know whether the machine this was run was a scotch-yoke type (generates pure sinusoidal motion) or a crank and slider type (degenerated sinusoid). There is also no label of rpm the machine was at, so even if X & Y were labeled and we knew the dyno type, we wouldn't be able to calculate the velocity, as we have no time data.

What most people are used to looking at is a force-peak velocity plot (f-v). To generate the f-v plot what is usually done is the dyno is run at various increasing RPMs. For each RPM, a f-d plot is created (maybe only internally to the dyno's acquisition system). From each f-d plot the max velocity and max force is pulled, for both compression and rebound. Thus, each f-d plot gets us one point on the compression curve and one point on the rebound curve for a f-v plot. Run enough f-d curves and you can create a complete f-v plot.

Bottom line: the data True Choice provided you isn't very useful, except for to say the curves are pretty smooth at some unknown stroke length and unknown velocity. Also, the curves aren't as symmetric as ideal to the left and right of zero displacement (but that gets into a very long discussion that I am no expert on - balancing hysteresis and bleed area).

-Steve

FF2Skip

Thank you, Steve, for taking the time to post all that. Other than the smoothness you referred to, can you deduce anything else in general with regards to possible "before" and "after" performance characteristics?

Windscreen

Without units on the scales, there isn't much I can add. If we assume the scales are the same for before and after, it looks like your adjustments at full soft are about the same, and full stiff rebound is increased roughly 50%. But not knowing what velocity this change is at is very limiting. Assuming the adjustments were the same for L & R shocks, it does appear they are reasonably matched, which is pretty good for a Koni yellow.

Again, what you really want to look at is the f-v plot. That is stop #1 in trying to understand what the adjusters do: how much authority do they have, do they affect low/high/all velocities, is there cross-talk between compression and rebound adjusters, and how well matched are L & R in the all important low velocity area (body control).

-Steve