9mm *should* yield around 0.59" (15mm) of free travel on a full weight, full tank S2000 with no driver/passenger.

NON CR S2000's all have rear springs hovering in the 300LB range.

447LB (8KG) springs are ~1.5X (150%) stiffer than a given stock rear spring.

The stock suspension has like 7/8" (22mm) of free travel. The stock bumpstops are softer and longer than the Ohlins.

The 9mm loaded Öhlins have ~148% less travel and ~150% the spring rate as compared to stock.

So...the Ohlins and stock rear suspension spends about the same amount of time on bumpstops.

The Ohlins bumpstops are harder. But the damper is also stronger in rebound...and is adjustable.

The reasons Ohlins needed to come to this 9mm compromise:
-They are trying to limit wheel movement so that the tyre doesn't contact the fender/bumper/liner/etc.

-They do not want to redesign the lower mount and raise the cost of the system.

-The previous MIN ride height (lowest possible) should still be achievable with 9mm of preload. Any more preload would result in a higher MIN height.

-They want to maintain droop travel without lengthening the damper stroke (cost, redesign).

The numbers they give are reference values and recommendations.

If you're fine with giving up one or more of the above factors/concerns, then...dial your own preload. Or buy one of the SBG kits or lower mounts that address the issue.

If your country vehicle codes are saddled with regulations...well...you're limited with what you can do. You have the same limitations as Ohlins does.

I am using aftermarket, pass thru mounts and 13mm of preload, which on MY car, equates to 26mm of damper free travel. A full weight S2000 probably needs like 17mm.

Having the 26mm of travel made a huge difference in ride quality for me. I truly have that magic carpet ride now.

 

i am running 10k springs at 12mm. I started at 8mm and increased because the car sat too low, the extra 4mm was a night and day difference

 

B Serious, What weight reduction mods would help? I know spare tire and probably exhaust and TP come to mind. I'm just wondering what can a stock S2000 do to hit the 9mm preload target without having to add more preload, and therefore raising the car further.

 

I have since replaced the trunk plastics. But...5LB shouldn't make much difference.

Removing weight also raises the car, though.

I figure if 35-40LB of that weight was removed from each rear wheel, and the motion ratio is 1.73:1, that equates to 70ish LB at the spring. Or about a 4mm extra deflection. Hence my recommendation that a stock weight S2000 use ~4mm more preload than I am using.

 

Maybe it's a stupid question, but looking at the two manuals, the OLD ohlins has 2mm of spring preload, and 28mm of lower bracket height and 420mm of shock absorber lenght, and the vehicle is lowered approximately 25mm than standard vehicle height.
The NEW ohlins has 9mm of spring preload, and 22mm of lower bracket height and no value for shock absorber lenght, and the vehicle is lowered approximately 25mm than standard vehicle height
So, now I'm wondering, how is it possible that on the new one with 9mm of springs preload, and less height on lower bracket, the car has the same lowering?

 

The smaller the "bottom bracket height" number, the lower the car is. You're threading the shock into the bottom bracket, thus shortening the system.

Kind of like screwing a screw into a nut. The further you screw it in...the lower the height of the screw.

The new bottom bracket height is 6mm lower than old.
The new spring perch height is 7mm higher than old.

So you first lowered the shock 6mm.
Then raised it 7mm.

1mm difference from old.

Probably a negligible change.

 

thanks for the tech info...
i had thought that adding preload raises the ride height of the car, so they are compensating by lowering the adjuster cup the same amount. The new mounting instructions add 7mm of spring preload compared to the old version. To compensate for this, they have lowered the cups 6mm (28mm original v -22mm new). It’s off by 1mm, but that is likely due to the cup bottoming out on the end of the damper. So the ride height might be off by a 1mm or so, and it should still be the same lowering amount of the old one. But i was not sure that this reasoning was right.

In addition to this, i have in my mind to swap a full set of Eibach race springs....8" x 600lbs on the rear and 8" x 700lbs on the front. since they are 203mm (3mm higher than ohlins one) and wanting to meet the standard Ohlins manuals specs, i would have about 12mm of total preload in the rear end and 5mm of total preload in the front end, same bottom bracket height on both, so i think same ride height as with the standard ohlins springs.... is it right? What does it mean?

 

Stiffer springs will raise the car. You don't need or want 12mm of preload with a 600LB rear spring.

Figure a full weight S2000 puts 820-850LB into each rear spring.

including the MR.

You need like...6mm of preload to have 1" of free damper travel with a 600LB spring.

Spring length can be disregarded. It won't affect preloads because the spring perch is threaded.

Explanation:

Average rear corner force (not weight) is 835LB by my prediction.

You say you want a 600LB spring.

With a 600LB spring:

835/600 = 1.39.

The damper has 2.13" of clear travel when its fully extended.

When you put the car on the ground, it compresses the shock 1.39.

2.13 - 1.39 = 0.74".

So with 0 preload, you have 0.74" of clear travel.

If you want 1" of clear travel, you need to raise the spring position 0.26". Which is like 6mm.

That's why you add 6mm of preload to a 600LB spring to achieve 1" of free travel.

Easy things to remember:
-The clear travel of the base Ohlins rear damper is 2.13".

-A stock S2000 puts like 835ish LB (averaging it out) into each rear spring. Please do not multiply this by MR. It includes the MR.

Your achievable ride height depends on bottom bracket position and amount of free travel you want.

Until a certain point, you basically just match spring height rise with bottom bracket drop. Raise the spring 0.25"? Want to keep the same height? Drop the bottom bracket gap by 0.25".

Tp expand:

According to SBG, the rear MR is 1.73:1 (wheel to shock). You should be able to predict ride height by expanding on the Ohlins base measurement.

Ohlins say that that with Ohlins' settings, the car will be lowered 1" (25mm).

Someone check my prediction here....but with their NEW 9mm preload on 8K springs, the damper will compress around 1.5" from initial preloaded spring length.

Meaning their 7.87" spring is preloaded to become a 7.52" spring. With the car on the ground, it becomes a 6.02" spring.

7.52 - 6.02 = 1.50

With the car on the ground, an 8K spring with 9mm preload will leave you with like 0.6" of free travel, for reference.

So according to Ohlins' manual, with a 1.5" damper/spring compression, and a 22mm bracket gap height, the car is lowered 1".

You want 1" of freeplay? Regardless of spring rate, you will need to make it so that the damper compresses 0.4" LESS than before.

You with me? It compressed 1.5" with their base setting. That resulted in a 0.6" free travel. You want 0.4" LESS compression to achieve 1" of free travel.

If you make the damper compress 0.4" less and achieve a 1" freeplay using whatever method you choose (preload or spring rate)...that results in the car sitting (0.4 ×1.73 =) 0.69" higher than Ohlins base 1" drop. Meaning you will have a 0.3" drop.

Want to keep that 1" ride height drop?

Lower the whole shock into the bottom bracket by the same amount you raised the damper stroke (0.4").

If the bottom bracket bottoms out...then you're left with:
[(the difference) × 1.73] = ride height change.

Easy peasy.

 

So B, say I have the 10KF and 8K rear and I want as much free travel as possible. Say I also have the SBG rear lower mounts. What should by preload be? Also is this independent of ride hight. Looking to drop 1.5 inches.

 

I am finally getting to installing the 10k springs I have for the rear DFV. My target ride height is 13.25-13.375. If I recall the ideal preload would be around 10mm for a 10k spring, right? At that preload, how low can I get the ride height?

If I can't make my target I will change it or the preload. I am done buying suspension parts.