Koni re-valve - NB Miata?

 Setting up the question:

On 400/300 springs, with rebound dialed in, I thought Koni's rode really nicely at ~ 12/12.5 ride height with FCM stiff 36mm bumps.  It was crisp and comfortable (to me).

I know Koni yellows are good to 500lbs or something, but it's never ridden quite as well with any other rates.

I know that damping is set based on spring rate/frequency and the  compression/rebound force that dampers generate at a given shaft speed.  It also seems that rebound impacts ride quality more than compression.  I also know bump stops play a role. 

I'd like to run 500/350 ( for auto-x/street), and think, based on reading, that a reasonable ride for the street could be achieved with the right damping.

I found some force/velocity graphs for Koni Sports v. Race, and they look to run 20-25% stiffer for both compression and rebound,  BUT, the rebound on the race units has a pretty steep ramp up. 

The question:  if I kept the compression of the race units, but ran rebound curves/ values at the sport levels (or a bit more), am I likely to achieve the crisp (relatively) comfortable feeling at 500/350 as I achieved with 400/300?

Now, the reason I'd like to play around a bit and try revalving  is because I'm stupid.  If I were smart,  I'd be buying something like FM Fox or Xidas, or even Tein or something.

Thoughts?

In reply to OldGray320i :

I can’t answer your questions directly, but I’m running 800/650 springs with Koni Race shocks on my 90. I had Koni Sports on my old 94 (now mtn’s car) with GC coilovers that were 400/320 IIRC. 

On my 94 at autox I always felt like the rebound needed cranked most of the way up, but on my 90 I’ve not yet gone past 1/2-way. Even at full-soft it doesn’t feel underdamped. 

More directly related to your question - bump valving is what makes the car feel “stiffer” going down the road - though if you have so much rebound that it sucks the car down onto the bump stops, you’ll definitely feel that too. 

Mine other point: I’m running the ISC top hats, with shaved bumpstops(that I doubt will ever come into play). Having the extra travel really transforms the car, as it allows the suspension to work, especially the rear. This is more noticeable on the street, since the pavement is typically rougher than autox. 

I would call Lee at Koni. He is a great guy and I know he could help you. 

Just don't be stupid and buy XIDAs or FM Fox? 

I prefer to use things specifically designed for the purpose vs trying to make something else.

In reply to Pete Gossett :

I've heard it said that too much rebound relative to spring rate is what causes the sucking down on the bumps; I've run about a turn, give or take, on my current rates, "decent" on the street, run a little more at auto-x, car does well. 

Re: street ride, too little rebound and the car just jiggles a lot.  More than ~+/- 1 turn and the car starts to feel a bit harsh.

In reply to dean1484 :

I emailed Mason there, who seems a good cat, he mentioned they aren't doing the revalves, but I should probably call and talk to Lee on the idea....

In reply to z31maniac :

I know not much is more expensive than being cheap, but there's also the sense of adventure that goes with it.  Plus, working way to hard re-inventing the wheel is sort of my thing. 

Koni doesn't do rebuilds any more, but they might be able to give you some insight on what kind of changes you'd want to make. Additionally propartsUSA (who I'd recommend to do the work) probably has some good ideas on what changes should be made.

In reply to OldGray320i :

Good luck!

In reply to dps214 :

I had reached out to one of the authorized rebuilders before I saw the fv graphs, and they noted "taking out some low speed".  I don't recall if it was Proparts or not, but I'll double back and give them a call. 

I know there's a sweet spot in damping force v. spring rate, and it seems like 400/300 is it for Sports on a Miata. 

I'd like to valve in kind for higher rate springs. 

We'll see what happens...