suzuka san

Hello all. I have seen the second spring on the Bilstein PSS referred to alternatively as helper springs and tender springs on other s2ki posts (and elsewhere). My understanding is that "helper" springs are only used to keep the coilover assembly together on full droop and do not impact the function of the suspension, while "tender" springs create a sort of step in the suspension travel that gives the system a progressive dynamic.

Can anyone confirm whether the PSS uses a tender spring or a helper spring? Not clear to me from Bilstein's website.

I am interested in comparing the front/rear spring rate ratio from my stock AP1 to the PSS. Other posts say the helper/tender spring on the PSS is rated at 85lbs. How does this interact with the rate for the main spring?

I'm trying to figure out whether the PSS is really sprung that much harder up front than in the rear--someone posted the rates for the PSS as 345lbs + 85lb helper front / 285lbs rear. Because if so, seems to be a much different balance than my stock AP1 setup, which has a softer spring rate up front than in the back according to this excellent post: https://www.s2ki.com/s2000/topic/818...nsion-springs/

Curious as to why the front/rear balance would be so different on the PSS. But perhaps the balance is not so different if the PSS actually uses a tender spring and the 85 lbs. acts to soften up the front rate. Which kind of seems intuitive to me, but Im a suspension noob.

Any thoughts?

Finally, anyone know how much of a drop the PSS give when set to the highest setting in the recommended height range?

Thanks



Not much info on the Bilstein site as far as I can tell.

s2ka

The helper/tender springs do both tasks, they keep the springs on the perches at full droop and soften the ride a little. They're fully compressed in most situations so they aren't a big factor on the spring rate.

Bilstein figured out good spring rates for the S2000 rates early. It took Honda almost 7 years to come around to almost the same settings with the CR. Your 00 car (and mine) had soft front springs and stiff rear springs, and stiff sway bars all around. It was OK on a smooth surface but lacked the compliance needed for bumpy conditions. It was biased for quick steering, but that was getting people in trouble on less than ideal roads, so Honda changed the suspension several times over the 9 year run. By the 08 iteration it understeered pretty bad, had a slower steering rack, and had electronic safety nets to keep people heading in the right direction.

https://www.s2ki.com/s2000/topic/818...#entry19542422

I believe the PSS9 instructions have been posted online, they show the max/min height range. You can get them pretty close to AP2 stock height.

http://art.rexbo.net/bilstein/pdf/e4-wm4-y529a01.pdf

http://art.rexbo.net/bilstein/pdf/e4-wm5-y223a00.pdf

The PSS9 is a very smooth and well damped coilover for the street and light track usage. Your best bet is to find someone with PSS9 on their car and go for a ride. If you're in SoCal you can check mine out.

Keep good tires on your 00 and make a few changes (PSS9 + AP2 sway bars) and it will handle great and ride nice.

User 121020

They use helper springs, not tender springs. Your definitions for tender and helper are correct. Helper are typically 10-25 lb/in springs. Tender springs have a large range and can be upwards of 500 lb/in.

For purposes of analyzing chassis balance with the PSS coilovers, use 345 lb/in front and 285 lb/in rear. I don't remember what year the PSS/PSS9s were released, but you'll notice Bilstein doesn't offer different spring rates for the AP1s vs AP2s. I'm sure there was some compromising in the spring rates so they could be fitted to either chassis without causing significant roll balance issues. Most people with AP1s move to a stiffer front spring or a stiffer front anti-roll bar (or softer rear anti-roll bar, for that matter), which shifts the roll stiffness bias towards the front.

suzuka san

Thanks for the helpful information all. I live in the Bay, or I'd gladly take you up on your offer s2ka--thanks.

Any idea why the PSS helper springs are rated so much higher than typical helper springs?

I understand that running softer springs in the rear than up front generally tends to induce understeer. Might I get closer to the OEM balance after I install PSS by chaning the rear sway bar?

User 121020

No idea why they went stiffer with their helper springs. They collapse once you load the chassis, which is why their spring rate can be eliminated from roll rate calculations. So, even though they're stiffer than most helper springs, they effectively act like helper springs.

In general, you are correct. Stiffer front springs or a stiffer front anti-roll bar will shift the roll stiffness balance forward. More load will be applied to the outer front tire, which will yield understeer once you push it beyond the limits of grip.

If you want a softer front end (or stiffer rear end), you could try swapping the PSS springs front-to-rear. Use the 285 lb/in springs in the front and the 345 lb/in in the rear.

You could also use different anti-roll bars to achieve the balance you want. You have to think about the suspension system as a whole anytime you are making spring, bar, or tire changes. Getting the roll stiffness balance right is critical. Unfortunately there is not one magical setup - everyone likes something a little different and there are a ton of variables.

s2ka

The PSS9 balance is very neutral, try it first before you change anything.

I've tried a bunch of sway bars, AP2 fronts and rears are a really nice combo for the street.

300 lb/in front (bushing says 26.5)
311 lb/in rear (bushing says 25.4)

[attachment=51818:IMG_3294.JPG]

suzuka san

Thanks. I'll definitely keep my AP1 bars at first and see how I like the setup, then maybe play with the AP2 bars down the road. Interesting that the CR set up is so disparate.

rota92

I run a 5 in the rear and 4 in the front on my PSS9's, with an Eibach front bar on Hard.

It cleaned things up a ton, I'd like a little more spring rate but I don't have a lot of shit roads, and I don't drive it too much either.

Great stuff from Bilstein all around, as usual, they seemed to get it right.