2g set up for slight over steer

[My96AWD]

how would i set a 2g awd for slight over steer. total suspension replacement. bought the car with cut springs, and since then i blew the front struts. i was thinking koni sports and coil overs. but im wondering on the spring weights. looking for more performance then comfort. also i would like to only lower it 1 - 1.5 tops. or if i could even get away cheaper. but still have a car that i could take to the auto-x once in a while. but still be more of a 1/4 mile car. im getting the full kit from energy suspension also.

 

[ACM]

Konis, GroundControl or similar - 500f, 400r - RM antiroll bars f+r, get as much -ve camber as you can in the front, drop the rear -ve camber to .5 - 1* less than the front. Set the rear ride height ~1" higher than the front. Adjust to taste.

The rear Konis won't like 400s though, the ride will be uncomfortable. You'll be running them close to full stiff, and the compression gets really nasty in that last turn or so. Optimally have the rear revalved for (a lot) more rebound.

I do not like ES bushings, there's way too much spring to the material. Prothane, whilst being stiffer, are quite dead in that respect.

Charles

how would i set a 2g awd for slight over steer. total suspension replacement. bought the car with cut springs, and since then i blew the front struts. i was thinking koni sports and coil overs. but im wondering on the spring weights. looking for more performance then comfort. also i would like to only lower it 1 - 1.5 tops. or if i could even get away cheaper. but still have a car that i could take to the auto-x once in a while. but still be more of a 1/4 mile car. im getting the full kit from energy suspension also.

 

[jtmcinder]

The rear Konis won't like 400s though, the ride will be uncomfortable.

I agree that the ride is rough on 400 rears, but the (unrevalved) Konis did not seem to mind. I stay away from that last quarter turn on Konis no matter what, because of the rise in compression, and, yet, it felt like the rears were only slightly underdamped.

But then I got stupid and upped the rears to 450. Now the ride really sucked and the Konis could not control them and the car was both soggy and nasty-loose ... as in, even think about lifting and the rear was gone. So, I will be back on 400s next year and will say with some conviction that this is the maximum. I briefly considered sticking with the 450s and having the rears revalved, but decided against this for a variety of reasons. Most of all, there are better places to put the money and this is a daily-driven car.

- Jtoby

 

[grizzly]

how bout a little oversteer on a fwd 2g

 

[Poloturbo]

I agree that the ride is rough on 400 rears, but the (unrevalved) Konis did not seem to mind. I stay away from that last quarter turn on Konis no matter what, because of the rise in compression, and, yet, it felt like the rears were only slightly underdamped.

But then I got stupid and upped the rears to 450. Now the ride really sucked and the Konis could not control them and the car was both soggy and nasty-loose ... as in, even think about lifting and the rear was gone. So, I will be back on 400s next year and will say with some conviction that this is the maximum. I briefly considered sticking with the 450s and having the rears revalved, but decided against this for a variety of reasons. Most of all, there are better places to put the money and this is a daily-driven car.

- Jtoby

How about with some 350's in the rear would you recommend the full stiff turns on the koni's?
Ì was lapping some better times with the full stiff selection front and rear????
That's with a lot of camber though in the rear...

 

[jtmcinder]

No. Stay away from that last quarter turn (maybe even the last half turn) on Koni Sports because the bleeder being covered is two-way and that last bit will send the compression damping through the roof. Very nasty. Might as well have AGXs. The ride will suffer and the car will skitter.

- Jtoby

 

[Poloturbo]

I didn't know. Thanks for the input. What is your setting with the 400 rear and camber setting. Is it a bit more towards oversteer with a bit less camber and those sways? How does the car control with high speed trail braking?

 

[DG-FNR]

I have run Koni Yellows on our shop shock dyno.

At 3 inches per second and slower, the compression force on a Koni is completely independant of the adjuster setting. Koni Sports are rebound only.

I'm not sure about higher speeds - I also ran them at 10 inches per second - but didn't notice any crosstalk. It may or may not be there; I just didn't notice one way or another.

The first quarter turn off full hard DOES **DRAMATICALLY** increase the REBOUND force though. Something like 75% of the total adjustment range is in that first quarter turn.

DG

 

[jtmcinder]

Dennis, please provide actual numbers, since you have little to no seat time with the shocks in question to be able to provide first-hand experience. As you know, I long argued that the bleeders were one-way and that the apparent increase in compression was really a case of the shocks packing down when rebound was very high. But I was corrected by several people, some of whom pointed out that there was no one-way device on the bleeder in question. I can't remember what you said at the time, although I'm quite sure that you didn't stand up then and say what you are now saying, since that would have been agreeing with me and you'd rather be wrong (or silent) than do that.

- Jtoby

 

[jtmcinder]

In case you'd like to see some plots for Koni Sports and aren't really in the mood for the current episode of "I've got a secret" to wind down, here you go:

http://gandalf.la.psu.edu/cinder/tech/shockmath.htm

I'm sorry that I never got around to converting these to the usual format. But, even in this format, you can see the lack of any effect on compression due to the change in adjustment. Unfortunately, we don't know whether these were the extremes of adjustment or whether the guy running the dyno (who was an expert on Konis) knew to avoid the stiff extreme.

On the flip side, if you have a Koni Sport off the car and try compressing it with the shock dyno that comes for free with a standard human body (i.e., a body with hands), you will quickly convince yourself that something is up. It is much harder to compress a Koni set on full stiff than full soft (and, of course, it takes longer to re-extend on full stiff than full soft).

Given the lack of good, public data on Konis (after all, a hand job is not what I'd call "good" data ... it might be "hard" data, but it isn't "good" data, tee hee), it would nice if someone who really wants to be thought of as giving to the DSM community would step up and post plots of Konis in the better format with the adjustments clearly labeled.

Like that's going to happen.

- Jtoby

 

[DG-FNR]

Au contraire - I drove on Koni Sports for nearly a full season, and I did a lot of testing on them before I moved to ShockTeks.

I'm pretty sure whatever post you choose to try and drag up from that era will have me mischaracterising the way they operate - at the time, I didn't know about shock dynos and I believed that identical shocks on identical settings were identical. Now that I HAVE a shock dyno and use it every day as part of my job, I know better.

Here are the forces from one DSM Koni front shock. Keep in mind that there is so much variation shock-to-shock in a Koni that giving a force value at a certain adjuster position is only true for that specific shock. The trends seem to hold though - all the Sports I have dynoed to date have had essentially no crosstalk into bump from the rebound adjuster.

Values are bump and rebound at 2.5 in/sec

Full Hard 98.05,-671.93
1/4 turn 102.64,-402.23
1/2 turn 99.31,-324.54
1 turn 100.58,-274.60
1.5 turns 101.52,-268.12
Full Soft 101.39,-246.78

As you can see, compression varies only 3 pounds from setting to setting.

DG

 

[jtmcinder]

Values are bump and rebound at 2.5 in/sec

Full Hard 98.05,-671.93
1/4 turn 102.64,-402.23
1/2 turn 99.31,-324.54
1 turn 100.58,-274.60
1.5 turns 101.52,-268.12
Full Soft 101.39,-246.78

Wow, thanks. That matches the plots from Warren very well, too. Which takes us back to that debate several years ago on the Yahoo list, where Fedja and Charles were arguing that the adjuster did affect compression and I said that it did not. The thing that convinced me back then was the hand-dyno test. Can you explain what causes this change (without changing the data from the mechanical dyno)?

- Jtoby

ps. isn't it amusing how this was one of the topics that was raging at the time you banned me from your group? I find this hilarious since we are probably about to end up on the same side of a discussion vs Fedja and Charles.

 

[jtmcinder]

This is very interesting, making me wish that I had converted Warren's plots a long time ago.

My experience is that it's the last quarter turn that makes my car skitter. Well, if you take those numbers and combined them with the rather unscientific rule-of-thumb with regard to how much rebound is required to get a car with X springs and Y natural frequency to start packing down, the cut-off is right there at a quarter turn.

So, again, all that is left is to explain the hand-dyno pseudo-data.

- Jtoby

 

[DG-FNR]

No. Stay away from that last quarter turn (maybe even the last half turn) on Koni Sports because the bleeder being covered is two-way and that last bit will send the compression damping through the roof.

But, even in this format, you can see the lack of any effect on compression due to the change in adjustment..

DG

Learn: http://autocross.dsm.org/books.html

 

[DG-FNR]

Now as far as oversteer is concerned, it can be had on corner entry, but not (reliably) on corner exit. An AWD is NOT a RWD.

See http://autox.dsm.org/diffs.html for an explanation.

DG

Learn: http://autocross.dsm.org/books.html

 

[jtmcinder]

See http://autox.dsm.org/diffs.html for an explanation.

Oh, man. Please tell me that you've fixed this page and we don't have to have the how-diffs-work debate again. We're doing pretty well today. No need start acting like children again, right?

- Jtoby