PSS9

325lb/in front springs - progressive
345lb/in rear spring with a 115lb/in tender or helper spring - linear

I'm very surprised to find out the the front springs are progressive and that the rears are linear. The tender springs add no progressive rate, just kkep the springs from rattling around under full droop conditions.

It has been typical, in my experience, to find linear rate springs in the front and progressive rate springs in the rear of front wheel drive cars. The reasoning is, or has been, in an effort to cure understeer a heavier rear rate is required. Achieving this rate with a linear rate spring is at the expense of ride comfort at the back end specifically. So, employing a progressive rate in the rear allows lightly load backends to ride somewhat more comfortably.

To my way of thinking, linear front rates eliminate the potential 'steps' in progressive rate springs as weight is transfered from rear to front under cornering conditions.

Not sure about this...Someone smarter than me care to comment? I'm baffled.


Michael

 

i'll make a comment or two.

first, a true progessive spring is hard to find; you can tell by checking if the pitch is continuously changing. (often confused with dual rate, where there are two pitches wound.)

second, under cornering: more weight is shifted to the outside, so a progessively stiffer spring F or R would alter the yaw attitude of the car differently under more severe weight transfer. (typically the front outside would compress relatively more compared to the rear)

under braking (before cornering), weight is evenly shifted to the front so a progressivly stiffer F would tend to keep the car more level F to R under heavier braking, (and the opposite if the rear were progessively stiffer)

 

Jim, thanks.

I completely concur with your first and second paragraphs. I've driven some dual rate springs masquerading as progressive rate springs and I could definately feel each step...a little disconcerting when really pushing the car.

What you suggest in your third paragraph seems counter intuitive to me; if we compared a linear rate spring of a given weight to a truely progressive rate spring who's heaviest pitch was the same as the linear rate spring, wouldn't the linear rate spring keep the car more level?

I'm trying to compare apples to apples -rates - and perhaps this is not possible with linear and progressive rate springs.


Michael

 

I guess we need to know if the linear rate is midway in the rate range of the progressive spring. eventually, it will take more force to compress the progressive, or conversely, the same force will compress it less once the progrssive rate exceeds the linear rate.

sounds like some weird transitions would occurr, f/r. as the rates start to cross with more and more force.

 

I learned, albeit too late, that a well designed truely progressive rate spring's progressive 'nature' should control jounce or minute wheel movements afterwhich it should fairly rapidly take on the characteristic of a linear rate spring.

I guess my original question about whether progressive rates are better on the rear of front drivers or on the front may be answered by, it depends...on what me, you, or they are or were looking for. The Intgra Type R I drove had linear rtaes up front and truely progressive rates in the rear. Made for a nice ride, not nasty habits. If I remember, front rates were 250lb/in and rears pitched from 175 to 250lb/in.

Funny, the more I dive into this stuff the less I know.

 

I'll disagree with this statement.

Off-the-shelf suspension kits aren't going to "cure" understeer. Doing so would make them dangerous to the average driver. I'm not saying that they might not reduce understeer, but they'll certainly leave quite a bit on the table.

I'm not sure why they would put a progressive spring in the front, or for that matter, why they would waste they waste the money on the tender spring in the rear. Overall, the set feels like a compromise between what a performance-minded engineer wanted to build, and what the marketing department thought they could sell.

 

'Cure' was perhaps a poor word choice...but context is what makes language understandable without requiring outright accuracy.

Slow speed oversteer and highspeed understeer - within limits - is the preferrable balance. The degree of either depends upon many things inlcuding the skill of the average driver. All of my spring selections to date have been custom and not off the shelf.

One of the reasons for using a tender spring is that a shorter spring can be used. A shorter spring is lighter (less unspring weight), and, is more likely to compress without the potential asysmetric compression of a taller spring. I've always attempted to use the smallest diameter, shortest spring possible for a given lb/in. My personal limitation for a daily driver is noise. So I gravitate towards a somewhat taller spring in an effort to keep things tight under full droop conditions.

Springs are, by the way, a very big compromise.

So the question remains, why a progressive rate up front???

 

I certainly cannot imagine a good reason.

I've always found it easier to avoid progressive springs altogether. They're nice when setting up a car for comfort, but often too little information is available about them for me to feel comfortable with them from a performance standpoint. For example, if you're actually able to get a spring rate out of one of these companies you tend to end up with a single number, which seems fairly useless for describing a progressive spring. Is this the maximum rate it reaches? Where does it start out, how much compression do you need to reach the maximum rate, and does it progress evenly or otherwise? All rhetorical questions, but nice to know nonetheless.

Unfortunately, most of these companies are eager to protect their secrets.

 

You and jlm point out my very problem with progressive rate springs; too little information. I'm forced to look at other manufacturuers, H&R's coilover for example. I cannot find their spring rates, I cannot tell whether or not these are true progressive rates - jlm quite correctly wrote that most progressive rate springs are in fact dual rate springs. The custom Eibach/Koni combos I've used in the past worked very well on the track but were punishing on the street...but I knew what I was buying and why. This Mini will likely never see the track. What's a mother to do???

Jeff, what set-up are you using?

 

Buy KW V1's, V2's, V3's or 2 Way Competition Great ride on all! V1's & 2's could probably handle minor rate changes with their adjustablity but come with 278 lbs. front and 222 lbs. rear. The 2 way Comps are built to order, you tell them what range of spring rates you might want to use and they build them! I spec'd a low end of 222 lbs. and they told me I could go as high as 500 lbs. with it's range of adjustment. I'm somewhere in the middle now. One warning with the Comps though, they aren't built for cold weather, I guess it's the oil they use, they get VERY hard when temps. are under 40 deg. Never had any problem with my V1's before the Comp's though.

 

Yea, I've called H&R before trying to get spring rates of products and they won't divulge the information.

I bought my car used recently with H&R springs preinstalled on stock shocks. I'm unhappy with the ride, but am doing the same as you - just looking over the options. My main issue is that I haven't decided what direction I want to go with the car. My recent suspension experience comes from running modified hondas on the track and street. I'm much more comfortable setting up a car for the track than I am for the street. Part of me wants to go all out and install some double-adjustable shocks on the car, and the other part wants to just stick with a comfortable ride.

I think the PSS9 would be a good street setup, but for considerably less money I could just add some Bilstein shocks to my current springs and have a comparable ride. $1500 seems a little high for what you're getting with them -- not to mention the insanely high MSRP. I try to avoid shocks that adjust compression and rebound damping at the same time. They make a noticable change in "feel" making someone thing they're doing something by cranking them to stiff, but I've found that they're less useful for tuning than a single control (like Koni).

Like most people, I'm really thrown by the lack of access to the top of the shock piston in the rear. I've always been able to quickly make adjustments, and although I rarely change them after the initial setting, I dread the thought of even the initial setup of something like a Koni. Were I to steer more towards a track suspension I'm a big fan of Advance Design shocks. The problem again is that BOTH adjustments sit at the top of the shaft. I'm left having no experience with KW, Leda, Spax - basically the majority of the available options.

As a side note... one thing you should try to do if you're considering an H&R option is to figure out who makes the shock for the application you're considering. H&R doesn't actually make any shocks themselves - they just rebrand other people's stuff. For example, the Cup Kits are repainted Koni yellows (complete with Koni adjustment ****). The high-end coilovers tend to use Bilstein dampers. Finding out which shock is in use for a particular application will give you some insight into their performance since there's generally more information about the original manufacturer than the H&R product.

 

H&R coilovers use Bilstein dampers. Bilstien's PSS9 coilovers use H&R springs.

Double adjustable dampers are fine so long as rebound and bound are independent. There is a relationship between the two, based upon my own experience; bound is best set at half to one third rebound rate for street.

In the past, I've used Koni dampers with Eibach springs in both Honda/Acura. The Dampers were SST valved, though I did not opt for the double adjustable mods. Very expensive. The above set-up was a very big hammer approach on the street. Would never do it again...great handling cars on a smooth road...terrible steering feel.

 

Is that true PSS9s use H&R springs. So I could change my springs rate on my PSS9s using H&R product?

 

So I was told by the powers that be at Helix - they sell both. The PSS9 system is reportedly more resilient.

Michael

 

Dont know about this as I had on the crap H&R coilovers last week and switched to the much, much better PSS9's this last week, and it is a WORLD of difference...

 

That would pretty much confirm what the folks at Helix indicated; PSS9 is more resilient...funny...given the manufacturer relationship here.

Good luck with the PSS9

 

I really like my PSS9s. I run them pretty stiff with 2 up front and 5 in the rear

 

I broke them in with 6 in front and 9 in rear, and now I am at 6 all the way around, and will go to 4 later this week.... Still loving them!