Topic: Soft or Hard - what's best for handling

[Ben L]

   No amount of rebound adjustment allows you to overcome the stiffness of the spring rates. 

[kennysabarese]

That's good to know. The good thing is you can put pretty much any spring you want on coilovers... The highways are really crap here in jersey...

After putting the z0k swaybars in, there is very little body roll, so maybe I can get away with a little softer spring...

[Ben L]

I was able to order my BCs with other-than-their stock springs (6k/mm in front and 8k/mm in rear vs. 7k/mm BC stock), so you should be to get softer springs if you want. 

May be defeating the purpose for track driving though.  The stiffness comes in handy there; better/faster weight transfers, etc.

[Critterman]

Jim,
I run mine at 7f/10r from the softest on the street, still good feel and she who must be obeyed doesn't complain

[kennysabarese]

That's what i'm trying to learn here is what effect the 3 adjustable elements, springs, compression, rebound, have on comfort and performance. Since springs aren't easily adjustable, it would be nice to know if it is possible to get the best of both worlds.

[snaponbob]

SO much in this thread is correct and so much is not. WAY too much to cover it all. But ..................

1) Terminal understeer IS easier to correct than terminal oversteer. In either case, the nut behind the wheel screwed up !!!!
2) Some understeer IS nice to "live" with. The Kappas have SOME understeer -- in  street use.
3) SOME understeer is best in road racing or high speed conditions. MUCH more stable.
4) SOME neutral or oversteer is preferred in Solo type driving.
5) Chassis tune (other than alignment) is supposed to start with springs, THEN bars, THEN shock adjustments. Kappas come with SOFTER springs in front than rear, and without the bars would be loose. Kappas come with much stiffer bars in front than in back. (This is a matter of RIDE quality, not handling.) The bars induce the desired understeer that the supplied springs don't. If ONLY the springs were selected for handling, the avareage Kappa buyer would not like the harsher ride. Bars only marginally effect the ride.
6) Rebound (up to a point) will "control" springs, or rather what the springs DO when they uncoil. That is why more heavily spring cars have MORE rebound and LESS compression in the valving. Look at a car with worn out shocks that is oscillating up and down and you'll see what no rebound control does.
7) Once shocks, springs, and bars are selected and installed, (assuming tire pressures are set for best response) adding rebound at one end will induce TRANSITIONAL roll stiffness. Until the car has settled into its "steady state" in a given turn, more rebound in the front will cause tightening of a "loose" car or more understeer in a "tight" car.  Conversely, more rebound in the rear will free up a "tight" car, and oversteer in a "loose or neutral car. Rebound is the touchy stuff and can really screw up a well tuned suspension package if one is not careful. Example; are car handles great (for a given person, car, and setup) and someone increases the front compression. The driver will have a car that will turn in better, but then start to push. Lee Grimes of Koni warned me of this last year at Solo Nats when he revalved my shocks, and he was 100% correct. And playing with rebound in front or rear may make things worse. Quite the balancing act.
8) Of all the respondents in this thread, Ben has it about right ------ for autocross !!!!!!!! A well set up Solo car can be a wonderfull STREET driver, but nearly a death trap on a raod course!!!
9) If you have adjustable shocks, DON'T TOUCH the compression adjusters, but start playing with the rebound and see how the cars reacts. Even at modest speeds the feel will change. Set the rebound at mid positions on all four. Drive it with some reasonable gusto. Mentally note the feel. Now, turn the fronts 3/4 firm and the rears 3/4 soft. Repeat. Stop, set fronts 3/4 soft and the rears 3/4 firm. Repeat. Come back home and post the results to this thread !!!!!!!!!!!!!!!
10) BTW, installed springs certainly CAN be used to change the handling if they are adjustable. In competition (race or solo) raising and lowering one end and/or the other WILL change the roll centers and how those ends "act". Also, preload matters !!!!!!!!!!!!!!!!!

There. That should toast a few folks, huh? 

[Kelu]

I must quote someone from the other forum:
"My head just exploded." 

[Ben L]

Good thing my GXP lacks roll protection, and will never see the track! 

[Treeman]

8) Of all the respondents in this thread, Ben has it about right ------ for autocross !!!!!!!! A well set up Solo car can be a wonderfull STREET driver, but nearly a death trap on a raod course!!!

And that is probably one of the biggest differences between Ben and I.  I now enjoy autocross but my primary reason for owning the car is mountain twisties - more like a road course!  So, it is good to point out that there are different strokes for different folks.

[kennysabarese]

I gotta say since the body roll is pretty much gone with the rollbars. maybe i can put in softer springs, it certainly won't roll as much as stock...

[kennysabarese]

Of all the respondents in this thread, Ben has it about right ------ for autocross !!!!!!!! A well set up Solo car can be a wonderfull STREET driver, but nearly a death trap on a raod course!!!

Bob, FYI a month ago you told me that a street setup would be good on a road course r and that autocross is much different setup, which conflicts with the above statement.

[Ben L]

I think its a matter of degree and personal preference. 

Big Daddy likes 'em tight and neutral, on the autox course, street or track. 

The part that is easiest to adjust is behind the wheel. 

If the platform is decent, and you learn car dynamics and what is going on, you can adapt your driving to the conditions.

[snaponbob]

Bob, FYI a month ago you told me that a street setup would be good on a road course r and that autocross is much different setup, which conflicts with the above statement.

Tru dat. Just driving around EITHER setup will work, and a Solo setup WILL feel a bit more agile. Driving HARD on the street (not recommended, but people do like to play) will reveal the true natural of the setup, and a road race setup favors neutral to modest understeer, while a Solo setup favors neutral to modest oversteer. HTH.

[Critterman]

I know that the one autox I drove, with the setup that was recommended to me, it was very easy to steer with the gas pedal, and at the same time very easy to control.  Very predictable and probably what I will run this weekend, unless it rains then I am leaving everything soft

[Treeman]

You will recall which end of my car gave out first at that one autocross!!  Not the front!

[Uranium-238]

I seem to recall that my Sky demonstrating an uncharacteristic amount oversteer on Sunday afternoon...

[Critterman]

You will recall which end of my car gave out first at that one autocross!!  Not the front!

  BUT - you have stock suspension and a zillion pounds or air in your tires!