There has been a bunch of discussion in this forum about the ability of off-the-shelf Koni Sports to handle high spring rates, so I thought it would be appropriate to post this here.

After talking to Lee a couple weeks back, he said, "get the springs now, order some revalved ones in the meantime" (that's a lot of paraphrasing, we talked quite a bit) because I really didn't have enough spring rate for serious autocrossing, on serious pavement, on serious tires. The 400f/500r setup with the OTS Konis felt perfect but unfortunately the tires told a different story, and it'll be worse with Hoosiers, so I ordered up some springs.

If you need Eibach race springs I highly recommend ordering online from Fast Forty-Fours, a 944 racing parts specialist. I ordered them from the website last tuesday and got them by Friday. http://www.fast44.com I'm sure there are other companies who provide such good service, but I happened to stumble upon their site and was very happy.

I'm getting really good at working on this car's suspension. Took me 2.5 leisurely hours to swap the springs in my cramped 9/10th's-car garage.

The 800's vs. the 500's on the rear:



The 600's vs. the 400's on the front:



And, wonder of wonders, I did not in fact fly off the road in a blazing fireball when I went around a corner. The shocks are definitely overwhelmed on really big hits (railroad tracks, for instance) in the back, but they still feel capable in the front. I'm at full stiff now in the rear and a whole turn from full stiff in the front. On everything else, turns, transitions, small bumps and such they feel fine. So, not optimal, but better than ruining a perfectly good set of Hoosiers with fender cuts and too much camber gain.

The springs are stiff. Balance is good (see below), transitions are now lightning quick where before they were just damned quick. Can't wait to try it with real tires and not street tires.

I got the ride heights in the right ballpark but I have to fiddle with it a lot more tomorrow, right now it's 3/4" higher in the front than in the back. Then I'll have to borrow a friend's toe plates and smartcamber thingie and check it again. I'll have a review of their performance on an autocross course in about 12 days.

 

nice, I always like seeing posts like this! So you were ruining tires due to tire-to-body contact?

 

No, but it was a near thing on tires that are narrower with a bunch less grip than the Hoosiers that are going on the car. A lot of it was from lack of camber and the camber gain from body roll. They haven't been destroyed but the wear has been a lot less than perfect and the one time I did get a pyrometer on them the temps were all over the place no matter what I did with pressures.

I have some in-car video from the HPDE I was instructing at Saturday, and with a student in the passenger seat you can hear the right front rub mid-corner over a bump. I'll try to grab it from my friend whose camera it's on.

 

Running the Konis full stiff front and rear?

 

GspeedR:<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TeamSlowdotOrg &raquo;</TD></TR><TR><TD CLASS="quote">
And, wonder of wonders, I did not in fact fly off the road in a blazing fireball when I went around a corner. The shocks are definitely overwhelmed on really big hits (railroad tracks, for instance) in the back, but they still feel capable in the front. I'm at full stiff now in the rear and a whole turn from full stiff in the front. On everything else, turns, transitions, small bumps and such they feel fine. So, not optimal, but better than ruining a perfectly good set of Hoosiers with fender cuts and too much camber gain.

</TD></TR></TABLE>

Seems fine in the front. Rears seem to need more rebound damping on really big bumps.

I should mention, the car weighs ~2400 lbs with a full tank of gas, sans driver.

 

Ooops...forgot to read.

I'm sure you spoke with Lee about this, but...

Have you considered running the front at full stiff? It seems that 600# requires the maximum rebound damping available. I realize that you are going for a relative f/r ratio but do you think you're sacrificing a more optimal setup in the front to get it? Just some thoughts...

 

Sounds good

Interested in selling those 500 lb'ers? I only have 300 lb in the rear on mine right now, and have been looking to move up. Been driving on these rates for some time now and feel I am ready to move up.

Let me know,
Jon

 

I posted them for sale in the racing spring sticky thread.

GSR: First I have to get the ride heights closer to what they need to be and get the alignment right. I'll certainly be trying different shock settings up front now that my rears are basically non-adjustable. I'm going to fiddle with a lot of different settings in the next few days. Right now they feel fine up front, but as my last set of R-compounds will tell you, feeling fine and working right are sometimes not the same thing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">
Have you considered running the front at full stiff? It seems that 600# requires the maximum rebound damping available. I realize that you are going for a relative f/r ratio but do you think you're sacrificing a more optimal setup in the front to get it? Just some thoughts...</TD></TR></TABLE>

Wouldn't running full rebound force the damper to rebound slower.. ie making bottoming out more likely?

Or are your reffering to the track/autox setup?

 

it's camber loss in roll, not gain.

full stiff on the damper with that much spring rate will not cause the car to jack down. it will be much harsher on the street though.

when i was running 600/500 and 600/700 on my ots shocks i ran them on the street at full soft with no problems.

with that much rear spring it doesn't matter what dampers you've got or what they are set at, the car won't like big dips or bumps. the back literally skips across.

if you thought the car turned in good now, wait until you get your rear shocks revalved.

i don't know what you've got for a front swaybar, but you may still have rubbing issues on your outside front tire. especially once you go to hoosiers. i'm running more front spring then you are with a 24mm front bar and on falkens i still get the outside front to rub. all the more reason to flare your fenders.

nate

 

Gain in numerical value of camber then, or am I picturing it wrong? I've seen it used both ways in some respected literature and it seems like a convention rather than a rule but I might not be thinking of it right.

I'm using the stock 26mm front bar and Comptech rear bar.

I expect it to be pretty brutal over the larger stuff, but the reason I say it doesn't like the really big bumps is that instead of taking the hit and then stopping the spring from boing-ing back so fast that it causes another bounce like it used to, I get two or three oscillations before the car settles down again.

I can't wait for the revalved units to get here. Counting the days...(months, more likely, they seem to be busy at Koni right now).

The current tires were Joke-ohama A032R-S in 205/50-15, which I've really been happy with (bought them on a lark, pretty much) and the new ones are Hoosier S03's in the same size. I'll be going to the 225/45-13 here in a few months.

 

So, I have it ballpark-aligned and the ride heights set. I took nate's advice and tried it on full soft. With the 400/500 I didn't like the compromise in handling vs. not-very-noticable improvement in ride from turning the Konis all the way soft on the street, but now it's pretty nice. Really takes the edge off of the small bumps and keeps the car from beating the crap out of me.

Alignment is a hair over (numerically under) -2 degrees of front camber and -1.5 rear, with 1/16" total toe out front and zero rear. The camber was measured with a camber gauge and the toe with homemade "toe plates" made from plywood, I'm going to get it on some more sophisticated machinery but as measured it can't be horribly out of whack.

It feels much more balanced now that I have the ride heights back where they make sense, and have enough front negative camber, or at least not a horrible deficiency in it. Everything happens a bunch faster, mid corner corrections in line, turn-in, oversteer, understeer, everything. It's nice. My street tires that seemed to match the car perfectly well now seem like they need to be way stickier. The same thing happened when I installed Konis on an otherwise stock 328.

Stiff cars: