ATownZ28

I'm looking at getting these, I have Koni SA's front and Bilstein HD's rear.
Any recommendations on spring rates? I am thinking maxing out both at 525 front and 140 rear.

ATownZ28

ttt anyone?

chupr0kabra

iTrader: (10)

Took me a second, but I think I understand the question now.

They're progressive rate springs, so when you see the fronts rated at 285-525lbs, that doesn't mean they sell different spring sets at different rates. It means the coils are spaced at varied intervals, so the more they get compressed, the higher the rate. Same with the backs being rated at 100-140lbs.


-Mike

Bad Blu Formula

iTrader: (3)

Good springs for your set up.

jimmyblue

iTrader: (11)

Good ride height, still a bit challenging for speed bumps
and swales. Harder than stock but not horribly so until
you get to larger deflections. I eventually went back to
stock minus spacer in the rear. I would not go any more
of a drop or more of a rate except on a track car. As
far as aftermarket springs I think they're among the best
though I have never had the chance to compare to 1LE
or SLP Eibachs firsthand, these would be other candidates
in that "drop range".

Sam Strano

iTrader: (41)

I think Jeff (that'd be AtownZ28) might think I'm selling him a bill of goods. I hope not, but we discussed this yesterday and the same question has been posted in a few places.....

I recommended these springs as the best workable option for what he does with the car. The max rates, which you are very near most of the time, are very similar to what I used on my coil-overs for rates in 2004 (and still the same rear springs on my car now). SLP Eibach's are NOT firm enough for the autocrossing job, and 1LE springs are not as firm, and actually do not lower the car at all... so no help on the negative camber side which he needs.

OneMeanZ

iTrader: (2)

I love my Hotchkis springs....hopefully shortly I'll have my rear Koni's

z28bryan

iTrader: (7)

I remember in the past there was a lot of discussion on progressive vs linear springrates. The Hotchkis seem to have a lot of progression. Last year Sam you didn't seem to want to recommend progressive springs because you can't progressivly damp them with shocks. Did this change or would you still recommend something like a linear ground control coilover set over any progressive set?

Sam Strano

iTrader: (41)

Not all progressives are the same. They are wound in different ways. While the "numbers" on two springs might be similar, they can in true function have VERY different working rates. The kicker is you can't ever know exactly what rate you are playing with. But with a educated eye watching the way the spring compresses and when which coils go dead (touch), you can make some very educated guesses.

Hotchkis springs are NEVER actually working @ 285 front, or 100 rear. That part of the spring gets sucked up by sitting the weight of the car on them when it comes off jacks.

All springs, even linear springs are in a way somewhat progressive. For example take a linear 292 like the stock front spring. It takes 292 to compress it 1", but it's already compressed some 4" or so when it's installed. They have a lot of pre-load in them. Then as you add load, it take 292 for the first inch, 584 for the second inch and so on. But you can take this kind of rise into account. "progressive" springs actually gain rate in a exponential fashion, and that if keep to a minimum is workable. It's when we are dealing with big changes in working rates that things become troublesome. And, just for the sake of detail..... You can damp a progressive spring. You just have to make the damping rate high enough to handle said spring @ it's highest rate. The issue there is again with RADICALLY changing rates, because when you are in the softer rates (assuming it's a spring that is like that), you then end up WAY overdamping the spring. This is why Koni's are a better recommendation when this type of spring is in use. Then it's the owner's choice about what he wants for damping, and where.

I recommend linear when it's useful. But that doesn't mean that all linears are better than any progressives. When progressives are chosen you choose based upon the working springs rates, NOT any random published rates. Another example is the LT1 Pro-kit. Front is listed 377-600, but they really aren't like that. The soft end is gone, bye-bye immediately... and the way they are wound, they are really more dual rate. The coil-spacing goes from this right to that, which is 600. The Hotchkis admittedly aren't just like that, but you can't use LT1 Pro-kits with Koni shocks because the spring windings block the adjuster access. I feel it's more important to have and use that and is a little variability in rate, because you can ADJUST your damping rate with that type of setup.

I have coil-overs. I have them for a reason. I race my car and rate changes for tuning, corner and cross weighting for tuning are needs I have. They are NOT needs the street or even occassional autocrosser or track day guy needs to have. There are bigger fish to fry. If you want them, and are aware of the pitfalls, then fine, go coil-over. But they cost more, you have to do some modifiying if you install them with Koni's, and that's not always easy. Someone recently on here bought some, then SOLD THEM because he couldn't get them installed. Went back to a set of lowering springs.

Bottom line, it's not easy to explain by e-mail. I will do my best to help you with those type of questions on the tech-line if you wish. But in the end, all you have to remember is that it's just not a matter of progressive vs. linear..... And you can (and do) run into situations were one end is linear (and good rates), but the other end is so wacky that the set is worse for a particular use than something that uses a pretty known progressive rate.

Clear as mud, right?

z28bryan

iTrader: (7)

Actually that was pretty informative. It makes sense that the further apart coils get compressed to essentially the same distance when loaded. It makes the BMR and the Hotchkis springs seem pretty good. Looks like they only drop the car an inch. The BMRs sound a little more stiff in the rear. I'm going by this link by the way: http://www.angelfire.com/my/fastcar/suspension.html

ATownZ28

Not at all Sam, I was just, as another post said, not sure that the 285-525 meant a progressive spring instead of options for linear springs. Thanks for your help!

Sam Strano

iTrader: (41)

Just kind of ribbing you a bit... maybe I shouldn't have, since I don't really know you. My apologies.

I understand, I didn't think about the possibility that one could view it that way, and I know that's not how it works... so it never dawned on me to mention it.