DavidNJ

What is the stroke of rear DFV damper? I thought it was typical to use 7" stroke in the front and a 5" stroke in the rear.

yessamgerg

I think you are thinking about spring lengths? The front DFV is ~3.25" stroke, the rear is ~2.125" not including bumpstops. The bumpstops on the DFV are not progressive like the OEM one and should generally be avoided. They are really there to protect against wheel to fender contact not as a useable tuning item. Their rate is 1500+ lb/in spring, when I did my initial install I could feel the suspension going rigid under small bumps when it touched the bumpstops.

DavidNJ

Penske requires an external reservoir (8300s) for a lowered S2000; for non-lowered applications (such as a street class SCCA autocross car) the 7500 DA can be used (note: it has a base valve). The TTX from PSI uses an external piggyback reservoir in the rear. The TTX is pretty trick, always applying the gas pressure to the low pressure side of the shock.

yessamgerg

True however the external reservoir adds a large amount to the cost. My point was that the design of the lower mount isn't very length efficient and if you had a better design you could squeeze in a lot more stroke. Interested to see what sakebomb has in store as it sounds like they might have just what we need...

B serious

They likely machined the bottom bracket to accept more thread. Its been done before. But you'll be limited in rebound stroke.

B serious

The misconception is that the Öhlins will engage the bumpstop with stock settings at static height.

Not true. I have the stock settings on preload. I havs 0.6" before bumpstop on my car. I can probably get about 0.8" without gaining any height (via additional bottom bracket adjustment). I am at 12.5" from fender arch to centre of wheel.

Or...

B serious

**my bottom bracket has not been machined. its stock Öhlins.

yessamgerg

Your misconception is that 0.6" is anywhere near enough clearance to the bumpstop. You measured that without a driver in the car, the driver sits almost entirely over the rear axle so let's say 125lbs on the rear axle. You probably didn't have a full tank of gas so we will say another 60lbs, entirely on the rear axle. You claim your car is 130 lbs lighter than stock, let's say 65 lbs is on the rear of the car. That means while driving a stock car you have 125lbs more on each rear wheel. To correct for load at the spring 125/0.575=217lbs. An 8k spring is 450lbs/in meaning 0.47" of compression vs your value. Through in the fact that most people forget to relax their control arm bushings and that equals most people are sitting on their bumpstops while actually driving their cars. Additionally on your car will hit the bumpstop with only a 1.25G bump (in industry 1G is the car sitting still), this is a tiny bump at which point your 450lb spring becomes a 2000lb/in spring. Unless you drive around on glass you are going to be constantly hitting the bumpstop. As you go closer to stock weight with a driver and topped off tank you will be riding around on the bumpstops the entire time.

B serious

why are you correcting for load at the spring??

You're confusing static weights with roll resistance.

I measured with a full tank.

The spring is being pushed on by the shock tower. If you're adding 125LB per corner, that's a 0.27" deflection.

I also said 0.8" free travel is possible without changing height.

For 1" pre bumpstop travel, the height change at the wheel would be like 3/8" ish from where my car is.

My spring compressed 1.53" with my car on it.

I preloaded 2mm. So 35LB.

That would mean I'm loading 718LB onto the spring.

The car probably weighs like 620- 650LB UNSPRUNG at that corner because the spring sits on a 25 or 30 degree angle.

the resultant force into the spring is 718LB

B serious

** I am estimating the weight I lost from the car.

SPRUNG weight, probably like 90-95LB lighter.

No soft top (oem hardtop)

No spare, no trunk plastics.

Recaro PP's on stock rails and custom brackets.

T1R 70EM single. stock cat.

No clue what my actual sprung/unsprung combined corner weights are.