Sorry if i am off topic in this thread, but i am happy to see someone else taking it to this level. Your blue curve on rebound looks like you are force limited (cylinder) and that is why you run out of data at less than 1"/s. I agree anything over 5"/s is nice to have but not relevant, i plot out to 10"/s because i have data and sometimes the knee in the curve happens after 5"/s on the stiffest of settings.

By correction factor i mean to calibrate the theoretical (calculated) cylinder force vs actual force you would obtain on a real dyno. There should be a correction factor due to losses in the system to slight pressure loss from regulator to the switch, and then to the cylinder. Plus add in some parasitic drag in the cylinder itself. The guy that makes these and sells them uses 0.8 times the calculated force. I wanted to get actual dynos and see is it a straight correction factor across all speeds, or more correction is needed at low speeds and less at high speeds. Hoping you had it figured out. This is a great tool for personal use. Using no correction factor is fine if all your plots are to compare on your dyno only and not to anyone elses data. This is what i use now until i can calibrate my system with an appropriate correction factor.

 

It is somewhat relevant...

I have not had the opportunity to calibrate to an expensive dyno. Like you said for relative changes it works great.

Using the dyno I have discovered a bad shock (KW V3) for a friend which allowed him to describe the issue and get it repaired by the seller. I also discovered a clogged bleed hole in my own shock resulting in a strange curve compared to the others that caused me to investigate.

It's a great tool to have. Do you have any photos?

 

double post deleted

 

There is a good introduction to monotube shocks article in the August issue of the SCCA magazine Sportscar. This just came in the mail today.

 

cool I'll check that out when I get home

 

How do you know when you have too much low rate compression? What will the behaviors be for the front and the rear?

In general I think the tire will get over loaded sooner than with less compression.

For the front would this be under steer when transferring the weight on corner entry? Maybe the ABS will come on sooner in a hard braking situation?

For the rear will it be harder to put the power down on corner exit? Maybe over steer if the outside tire gets loaded?

 

One symptom I had (with the Miata) was that the car just did not want to turn and trail braking only made the understeer worse. I expect it would also manifest in the S2000 as excessive power-on oversteer.

 

So I can offer some purely academic musings on your questions. I make no guarantee that any of this is right since it's not backed up by real world experience but it makes sense to me.

So firstly we assume that handling is dominated by low speed compression, as seems to be the established practice.

Compression is essentially a variable force that is added when that part of the suspension is compressing. So we can think of it like having too much spring just at the moment that you're compressing.

So when do parts compress?
The front will compress on corner entry, so by having too much front low speed compression that will cause understeer on corner entry.

The rears will compress on corner exit, so that would mean you would fight with oversteer on corner exit if your rears had too much compression.

The outside will compress during turns, so then bump on the outside and rebound on the inside are acting like a sway bar during the transient period. So, theoretically if you had too much compression in front, then you would also push, or if you had too much in the rear you would oversteer. But in this case the same thing could be caused by too much low speed rebound.

In addition to all of this, more low speed compression damping in general would load the tire faster, which may be beneficial or not depending on the tire and surface. I would think on a surface that required more gradual inputs like a wet surface, you would want less compression.

It would also obviously feel really harsh on highly transitional courses while not feeling as harsh on less transitional courses if you had too much compression in general.

Anyway, a quote by Carroll Smith comes to mind that I looked up for exact wording:
"Sometimes I think that I would have enjoyed racing more in the days of the friction shock. Since you couldn't do anything much to them or with them, I would have spent a lot less time being confused."

 

On my stock car I could make the fronts shudder on entry on low-grip surfaces. I'd actually feel them starting to skip a little. Backing off the compression damping eliminated that.

 

Drew, did you have the 8100, 8300, or 8660 compression cans?