why would I want the very stiff damping settings on track? I mean as long as the shock keeps the tire from bounding up and off the pavement, why would I want anything stiffer than that? wouldn't I just be decreasing traction by making the tire "skate" more?

I have front and back set to almost full soft (like 8-10 out of 30 clicks) and just leave it at that, except if the car pushes too much and I make the rear a little stiffer to reduce rear traction and get a more neutral handling car (this is after I've made tire pressure adjustements).

Any reason why I should go stiffer for track use? not sure I understand how I would benefit from it.

PS: bone stock IX; BC racing BR series coilovers

Thanks for the help.

 

Short answer without going into too much detail, to help control body roll.

 

using shocks to reduce understeer is hard unless you have a bump/rebound/high speed and low speed. I couldnt get the car do do what i wanted when I ran single adjustables.

What are you trying in terms of tire pressure?

Kyle

 

I'm on street tires (RT615's) and I am running 32 front (cold) and 30 rear (cold).

I'm lower in back because I have 10k springs in the rear and only 8 k in the front, and with the same tire pressure the car is way loose.

-2 f / -1.3r camber, btw, and very very slight toe in in the rear

 

It sounds like you are asking, "Why would I want overdamped springs?".
You don't.
Dampers are used to control the spring. What you want is ideal damping. You don't want damping that slams the springs back down nor do you want damping that keeps the springs from compressing properly. It's all about balance. Increasing bump/rebound can and does help your car maximize grip from the tires.

Search around and learn what you can regarding suspension basics first, you'll answer your own question quickly.

 

wow... starting with the same pressures front and rear creates a loose Evo???

i thought you wanted to reduce understeer? A loose evo is what people search for

Kyle

 

well, "loose" evo style: push under power, and then snap oversteer on throttle lift

at least that's what mine does.

 

Your problem is in the front. Search threads, this has been discussed many times.

If you want to get rid of your power on understeer, try:

1. More camber in the front
3. Fix the front roll center w/whiteline kit
4. Make sure car isn't lowered too much.

Shocks are more effective in changing transient behavior such as turn-in than steady state behavior such as through the middle of the turn.

Driving style is also a big factor, as Evo's easily roast the front tires if driven improperly.

 

+1

Higher spring rates are used on race cars for different reasons. The damping has to to be increased to properly damp out the higher spring rates. As pointed out, the transient response can also be tuned quite a bit using the shocks as well.

You are right in saying that if the shocks are set too stiffly you may lose traction.

If your problem is steady state you may also want to try playing around with the sway bars in addition to the suggestions already made. There is more than one way to get the same end result and the only way to figure out what is right is to test.

 

Thanks for the responses.

I've upped the stiffness significantly for a weekend, and noticed better car behavior, so even if it just makes the car "feel" better/funner to drive that's worthwhile.

So for a given spring rate, how does one determine the ideal level of damping? is there a method? I suppose I've heard of shock dyno's but wouldn;t know where to find one...

 

It is fairly complex to calculate the exact shock settings because you need to consider bump vs. rebound, high speed vs. low speed, and much more.

However, if you want to get your brain around the idea, think of it like a screen door with a spring closer and a shock absorber. If the shock is worn out, the door slams shut and is UNDERDAMPED. If the shock is real stiff and the door takes all day to close and lets the flies in, its OVERDAMPED.

Shocks should be more or less CRITICALLY DAMPED. Critically damped means the door closes just right...as fast as possible without slamming. The actual definition of critically damped is that the door would overshoot by only a few percent, I forget the number, if it could keep swinging the other way.

As it applies to racing, if the shock is overdamped on compression, the tire will skate as it is subjected to very high transient loads as the shock slams the tire into the pavement.

If the shock is overdamped on rebound, it will 'jack', or continue to compress until the suspension is completely bottomed as you go through a turn. This happens because the spring isn't strong enough to overcome the force required by the shock to get the wheel back up quick enough.

If the shock is underdamped on compression, you get bottoming and too much vertical motion. Similarly, if the shock is underdamped on rebound, you get the floaty cadillac style whoop de-doos.

Shock dynos are good for testing shocks and rough setup, but ultimately you have to tune shocks at a particular track.

If you want to get tricky, start thinking about how you can use the shocks to adjust transient response in different parts of the turn, especially as the car car reacts to brakes and throttle...i.e. make it more stable on turn in and looser at the middle or exit, or whatever you need.