Ran my first autox on a good surface yesterday, Car worked amazingly on the Gravel I ran it on a week ago but wasn't soo hot yesterday on concrete. (which when I saw the spring rates that came on the car was the complete oppsite of what I expected)

Bought the car a few weeks ago with Bilstein PSS9's on it. They aren't staying and go back to the owner as soon as my Koni DA's show up. But the car currently has 650lb front springs, and 900lbs rear springs. On concrete this is what I experienced. STU so Kumho MX's. Could the MX's be the reason for the lack of turn in. I'm used to running on hoosiers so maybe i'm just going to have to learn to leave with street tires numb character. Anyone else have experience with MX's.

NO turn in on concrete. I mean none. Turning the wheel was a Mere Suggestion of the direction you wanted to start moving in.

Steady state cornering was Nice the car was ever so slightly controlably loose. Very modest oversteer except when I got offline in the gravel it got VERY bad. And low speed corners had the usual Understeer, but a little worse then i'd like.

However It was nearly Impossible to put the power down. Gas pedal = immediate oversteer even in 3rd gear. My girlfriend had a horrific power oversteer 3rd gear spin which lead to 3 hours of vaccumming grass out of the car. I know for street tires my spring rates will be MUCH softer.

This not being able to put the power down really is scary, as I just felt like I was waiting and waiting to accelerate out of corners.
Is this common for running a high rear spring rate or just common on the fact that I've got 900lbs springs back there now. If I go mucho softer on the rear and say 450ish up front am I then going to experience alot of steady state understeer?
Anyone succesfully running lower rear spring rates without Moton's?

thats a hugely biased rear spring rate. Are you running no rear swaybar at all?

If you ARE running a rear swaybar, you might try backing down to an 800lbs rear spring. Id also check the alignment.

with springs that stiff it out to turn in fine. Maybe the shocks are busted completely.

Myself and matteucci are extremely fast (well he is, im just 'fast') with lower spring rates than that. Him: 550 front, 700 rear, me 600front, 750 rear. With Koni SAs. We are in 325s though so not as much power to put down.


Ran my first autox on a good surface yesterday, Car worked amazingly on the Gravel I ran it on a week ago but wasn't soo hot yesterday on concrete. (which when I saw the spring rates that came on the car was the complete oppsite of what I expected)

Bought the car a few weeks ago with Bilstein PSS9's on it. They aren't staying and go back to the owner as soon as my Koni DA's show up. But the car currently has 650lb front springs, and 900lbs rear springs. On concrete this is what I experienced. STU so Kumho MX's. Could the MX's be the reason for the lack of turn in. I'm used to running on hoosiers so maybe i'm just going to have to learn to leave with street tires numb character. Anyone else have experience with MX's.

NO turn in on concrete. I mean none. Turning the wheel was a Mere Suggestion of the direction you wanted to start moving in.

Steady state cornering was Nice the car was ever so slightly controlably loose. Very modest oversteer except when I got offline in the gravel it got VERY bad. And low speed corners had the usual Understeer, but a little worse then i'd like.

However It was nearly Impossible to put the power down. Gas pedal = immediate oversteer even in 3rd gear. My girlfriend had a horrific power oversteer 3rd gear spin which lead to 3 hours of vaccumming grass out of the car. I know for street tires my spring rates will be MUCH softer.

This not being able to put the power down really is scary, as I just felt like I was waiting and waiting to accelerate out of corners.
Is this common for running a high rear spring rate or just common on the fact that I've got 900lbs springs back there now. If I go mucho softer on the rear and say 450ish up front am I then going to experience alot of steady state understeer?
Anyone succesfully running lower rear spring rates without Moton's?

Are those PSS9's custom valved? Sounds like you might be underdamped. Those rates are similar to mine, though I am on RComps, no experience with them on street tires. What are your alignment settings? You need a pile of camber in front to get that car to work well, somewhere around -3.5 or more. Give us more info!

I'll be honest. Since I am sending the Bilsteins back to the previous owner (part of the deal when buying the car) I've never bothered to check alighnment. He claimed the car was set up for road atlanta by some race shop in atlanta. I think I remember him saying -4 camber front , -3 rear. 1/8 toe out front. 1/8 toe in rear. But I've never checked it since this suspension will be on the car a maxium of 2 more weeks.
I'm just REALLY torn for spring rates on the koni's. I need to pick that this week.

I saw the 325 in houston for the tour. You guys were MOVING in that thing in DSP. I was having the rather Lackluster performance in Sipes Z4 after our Miata broke. I wonder if you can get away with the stiff rear springs because the 325 does make much less power and therefore less likely to bring the rear out under power. I know Tunnell and Piccone are running soft rear springs but from what I understand. that won't work unless you splurg $$$ for the motons.

WOW, if you are really at -3 in the rear, that could be a big part of your problem. Try dialing it back to -2ish, that will help you get the power down for sure. The rest of the alignment sounds OK.

That wasn't me you saw, Ive got my own car and copied some of his setup. But my driving is still not quite that good =)


Try something along the lines of 600 front 750 rear and see how it feels. And back the rear camber out to -2.5 or -2 Ive found on other cars ( a corvette) that as the rear camber goes more negative than -2 the straightline traction really starts to go.

are you sure the rear diff is ok?


I'll be honest. Since I am sending the Bilsteins back to the previous owner (part of the deal when buying the car) I've never bothered to check alighnment. He claimed the car was set up for road atlanta by some race shop in atlanta. I think I remember him saying -4 camber front , -3 rear. 1/8 toe out front. 1/8 toe in rear. But I've never checked it since this suspension will be on the car a maxium of 2 more weeks.
I'm just REALLY torn for spring rates on the koni's. I need to pick that this week.

I saw the 325 in houston for the tour. You guys were MOVING in that thing in DSP. I was having the rather Lackluster performance in Sipes Z4 after our Miata broke. I wonder if you can get away with the stiff rear springs because the 325 does make much less power and therefore less likely to bring the rear out under power. I know Tunnell and Piccone are running soft rear springs but from what I understand. that won't work unless you splurg $$$ for the motons.

are you sure the rear diff is ok?


Oh man, Don't scare me. I just bought the car and Paid the BMW dealer $180 to get the driverside window to go all the way up and seal. And now the A/C compressor is making Noise. I don't even want to think about the dif.

I'll try backing the camber down when I get the new suspension. I've already orderd the front springs to be 450lbs (at Bob Tunnels advice for street tires). I think i'll give 500 a try in the rear at first. And if I don't like it. It's an easy change.

I've been running 500/600 on my 325is in STX. Works out pretty well for me. Car has always done well despite it's lack of preparedness (no alighnment, eyeball ride height, almost stock weight, etc...) compared to most of the competition.

Ok well I'm thinkin 450/550. I just got the call that my shocks will be sent back tomorrow. So the real fun begins.
Good bye lack of body roll.
http://home.comcast.net/~istewart16/119_1921.jpg