Would you say 800f 700r is too much spring? I am going to try softer rates at some point just to see how it feels with these dampers because I was running 675f and 560r with the bilsteins and it didn't seem too bad.


This is slightly off topic but how would you get more download on let's say the front of the car without aero? Would rake do it depending on how much you needed?

Thanks

 

wait don't springs also dictate ride height somewhat and isn't it better to set the rideheight low?
I mean the stiffer the springs the lower you can run the car without the shocks hitting the bumpstops

 

I totally agree but I think there's a good balance of lower CG and proper download right? Not sure if super low ride height also has proper download. I want to put my car into a computer program to see where we should be at but they're super expensive.
I have some room to work with and I'm at the height I think the car should be at. It's the only reason why I'm thinking about going softer.

 

Quote:

Rob, do you have any seat time in the "stiff" coilover setups?

No, the stiffest S I've driven is mine with ~630 front & ~570 rear springs on KWV3s. I turned a 1:21.7 lap (7/100 sec off the S2000 record) on Summit Main these springs and a stock motor. I'm probably going to try 680 front and 630 rear next. If it's slower I'll go back.

 

this a good read.
also don't forget that stiffer sways also make suspension less compliant when you hit a bump whith one wheel.
so affectively it's like putting stiffer springs.

what i mean is that if plan to go sways - don't go stiffest spring you want because sways will add more stiffnest.

also by altering height front vs rear you alter handling.
IIRC lower front goves more grip at front.

 

Swaybars are springs. Swaybars and coil springs both affect the roll resistance of the car (total spring rate in cornering) while only springs have effect in longitudinal dive/squat.

I'm not sure what download is.

Adding rake to the car (front down, rear up) will usually improve steady-state front grip a little, but there is a point where lowering the front too much in any car will reduce grip and induce other problems due to the geometry of the suspension.

 

Download is the weight that is applied to the tire in a downward angle or motion.
I think it was CG and Roll Center that effects this and of course aero will as well and there maybe others I haven't learned about yet.

 

I've never heard that term before. Any references to where its used? Is it just more load put on the tire?

 

IMO:

There are two things the suspension is suppose to do.

1) Keep the car flat through the corners, under power and braking (control roll, squat, and dive)

2) Maintain the contact between the tire and the road surface during road imperfections (real world)

These two work against each other and present the inherent compromise associated with the black art of suspension tuning.

I believe that there are a number of other factors that need to be considered when choosing the best compromise.

1) Aero component

2) Tire component

3) Circuit average speed (This is where data loggers and engineers really earn their money. A certain circuit might have a corner that is worth enough time to take precedence over the rest.)

4) Power

The rest is pretty straight forward.

Increase in spring rate increases high speed stability but decreases low speed grip.

Decrease in spring rate increases low speed grip and helps maintain surface-tire contact but decreases high speed stability.

Two examples:

1) Evasive S2000 (I'll take this down if you guys want)

Relatively low grip tires (255 non rcomp), decent amount of aero, ~90 mph average speed @ BW, and pretty damn high spring rates. Why?

They're tuning for a series of corners. At Button Willow there is a lot of time to be made up through riverside and phil hill, a lot. Its a high speed section with transitions, where its very difficult to be flat. This demands high speed stability, something the S2000 lacks. So they run a lot of spring. The S2000 is so good from the factory that you can afford to sacrifice a bit of low speed grip for high speed stability.

2) Jason's BSP AutoX S2000.

No aero, not a whole lot of power, probably ~75 mph average speed, but big rates. Why?

295mm Hoosier A6 on 18x11=G R I P

 

Billy, I'll have to find it, I should be able to post it up tonight.