Syncmaster

A little background... I picked up a used set of THREE 510 Series 4 coilovers (2 fronts and 1 rear) from a wrecked s2k (the other rear one was tweaked during the accident). I plan to purchase a new rear assembly (unless by the grace of god I find someone with a single rear for sale) from Fortune to replace the missing one, and have them rebuild and revalve the other three while I'm at it.

Car/driving habit info: Car is an '07. 245/40/17 square on 8.5 wheel setup. The car is not daily driven, but I still don't want a dump truck like ride because I will take a 200-400 mile trip here and there. I don't autocross. I might bring it to a road course maybe 1-2 times per summer, but mainly just for enjoyment on open track days, not competitiveness.

So here's my dilemma. I have a total of 6 SWIFT springs and I'm trying to figure out which ones to use, and which valving to match. I have a set of 12k, set of 10k, and a set of 9k. I want it to ride smooth and not be super jarring. through research on this site, it sounds like the ticket to a nice ride with these coilovers is to set valving higher than the spring rate - 2k higher or so all around.

So here are the options - let me know what you think, or if you have questions for me that may help advise:

• Option 1) 12k fronts and 10k rears w/ 14k and 12k valving
• Option 2) 10k fronts and 9k rears w/ 12k and 11k valving
• Any other options you think I should think about?

Which would you choose and why? Just looking for some help and advice from those who have more experience w/ coilovers than myself. Thanks in advance.

Apex1.0

Spring rates won't hurt your ride, but too much hight speed compression will. I think option 2 will get it done for you if you are running street tires. If the valving is as digressive as they say you should be good.

Is the adjustment on the 510 rebound only?

S2K Al

Hm, not sure where you read that. Valving isn't a specific number, certainly not something measured in the same units as spring rates either. Ride quality is dictated by a lot of things but one that is relatively easy to quantify is ride frequency, which is largely dictated by spring rates.

While everyone's definition of comfort is different, your proposed would result in a lower ride frequency in the rear than in the front, which would give a pogo-ey feel across rough surfaces like rippled highway.

Syncmaster

Yea I believe they are only rebound adjustable. Here is the list of specs:

Featuring our new "Ultra" Double Digressive Piston (UDDP) with revised shim stacks, this "Ultra" Digressive piston allows for massive amounts of low speed rebound force that helps with driver inputs such as dive, pitch and roll. Furthermore, the rebound force greatly tapers off to provide the driver with "blow off" This helps with large impacts on track helping the vehicle stay settled after hitting curbing at high speeds. After countless hours on the shock dyno and testing on the track, we are proud to offer these high performance coilovers that rival many high end European shocks that cost several thousand dollars more. Due to the ultra digressive nature of this shock absorber, this product is recommended for track use only.

*Assembled in the USA
*Dyno tested
*Dyno graph supplied with all 4 shocks
*Mono-Tube damper with high pressure nitrogen
*24-step rebound adjustable dampers
*Asssembly certificate (documenting build & QC)
*Radial bearing mounts standard (on MacPherson)
*Spherical Bearings
*Amsoil synthetic shock oil (the ultimate in shock oil technology)
*6061 Forged & Anodized aluminum mounts and camber plates
*Bright Dip Anodized
*Height adjustment independent of pre-load
*"Ultra" Digressive piston
*Compliant track suspension solution
*5 year Manufacturer's Warranty (1 year on piston)
*Swift springs upgrade available
*Rebuild-able
*Revalve-able
*Modularity - Upgradeable to 2-Way Canister*

Syncmaster

I read that on numerous threads here on s2ki (I don't have the links handy). The reason for the higher rate springs up front is to help induce understeer which I believe helps balance out a square wheel/tire setup... What do you mean by "lower ride frequency"?

DavidNJ

First, ride is a function of springs, anti-roll bars, suspension geometry (anti-squat, anti-lift), shocks, tires, and in some cases chassis stiffness and bushings. It can also be affected by unsprung weight.

Next, the Ohlins DFVs which are sold as street shocks (they are part of the 'road and track' collection) come with 10k and 8k springs. Any of the combinations with more spring in the front should work: 12k/10k, 12k/9k, or 10k/9k. All of these are pretty close to each other: 670lb/in, 560lb/in, 500lb/in. I doubt you could tell the difference between 10kg and 9kg on the street...even on the track it would be close. In a back-to-back test you could probably tell the difference between 12kg and 10kg...but if you drove them a week apart that would be less clear. A couple of clicks on the shock or slightly different cross weight or ride height from the spring perch adjustments could have a bigger effect.

That you have a square setup has transferred the bias toward the front. If you also added front negative camber that would take that further. So having higher front/rear split or a bigger front bar would help rebalance. In autocross the big front bar is common even with staggered spring rates.

A "pogo effect" or other bounciness is from not having sufficient damping. I don't think you would have a problem if you just told them what springs you are using and the other car info. You aren't in a competitive track situation, the shocks have some adjustability, and if you really had a problem that couldn't be fixed with an adjustment you could just get it revalved.

BTW, you should get the rear adjustment extenders. The rear S2k adjustment is buried in the trunk...the extenders should let you adjust with the trunk lining in place.

S2K Al

I read that on numerous threads here on s2ki (I don't have the links handy). The reason for the higher rate springs up front is to help induce understeer which I believe helps balance out a square wheel/tire setup... What do you mean by "lower ride frequency"?
[/quote]

Here is actually the very original article I read when trying to answer the same question for myself: http://www.rqriley.com/suspensn.htm.
It is defined within the "Ride Comfort" section of this article, near the top (although the rest of the article is a beneficial read as well).

freetors

Optimumg.com has a lot of good information about ride frequency and damping. Farnorthracing.com does too. OptimumG recommends having about a 10%higher ride frequency in the front on a perfoemance car for a couple reasons. First, flat ride theory (having the the 10% bias on the rear instead) promotes oversteer, and second, race cars are not terribly concerned with suspension comfort so the seesaw effect is ignored. Dennis Grant on FNR prescribes to the 10% bias to the rear.

With that said I chose 12/10 f/r springs for my fortune coilovers and they seem fine with respect to comfort.

User 121020

How about making this discussion about shock valving that works, i.e., a discussion of dyno plots?

Saying a shock is valved for XXX rate really says very little about the damping. Shock builders make assumptions about what damping curve shapes to use, damping coefficients, etc. A damper valved for 14kg/mm spring from vendor A could look completely different than a damper valved for 14kg/mm from vendor B.

If people have dyno plots from Fortune Auto, that's where this discussion could have meaningful benefit for shock tuning. Also, what works on the track or at an auto-x doesn't necessarily match theory. Theory is a starting point - but don't be afraid to try drastically different valving. This is where quality adjusters come into play.

Example:
S2000 - front rebound is well over critically damped and front/rear compression is well below critically damped
Elise - opposite my S2k, lots of compression, minimal rebound

My springs are 16kg/mm and 14kg/mm on my S2k, but saying my shocks are valved for those rates wouldn't imply anything about the actual valving.

Does FA provide plots with their dampers?

S2K Al

Something to mention regarding critical damping that some may not be aware of - the goal in all applications is not to achieve critical damping exactly, but to arrive at some percentage of it. A critically damped system returns the sprung weight to a steady state position in the shortest amount of time, with no oscillation. This would result in a lot of undesirable ride and handling characteristics.