Veloce Raptor

The day is still young, though, and Kibort & A Whyne have yet to enter this thread.

Geoffrey

The statements about roll are incomplete. You need to factor in the suspension geometry. The further away from the center of gravity the roll centers are, the more the car will roll, regardless of the spring rate.

Jarez Mifkin

Yes.

No.

Should I use stiffer springs when using center lock wheels?

Geoffrey

why would you think that centerlock wheels would be different?

Larry Herman

Saw that one coming.

wanna911

Here is a good question, how much can different tires in the same grouping (slicks) or changing to a dramatically different grouping change your suspension settings? Because obviously sidewall stiffness/flexion can be completely different if you are running a Slick vs a MPSC.

Do you start from stratch or from the baseline.

Jarez Mifkin

Veloce Raptor

Tires do comprise part of the suspension, so changing their characteristics will change the way the suspension reacts & manages the contact patch.

Rassel

Those should also cure a bit of the lack of driver comfort you mentioned.

Sean F

what is a spring?

mark kibort

I've driven two cars one stiff and the other supple. The stiff car was faster around the turns by 5mph and down the straight by 10mph. So, that has to be the way it is. (A little stupiditiy for Chris)

Seriously, thats another one that depends. Its not only road conditions, surface charactistics etc, but also track layout. (transisions, etc). Tight "S" turns, elevation changes, all play a part on which works better. One thing I stubbled across was that a soft suspension seems to work better for most tracks. I think the WCGT guys have all drifted toward softer suspension for more compliance over the years. I dont have much experience in playing with the spring rates, but I would like to go to the stiffer spring side as mine as I have always been undersprung compared to my competitors. Other cars like mine that have the stiffer springs seem to be way loose compared to mine when watching their in car videos.

Interesting topic!

mk

2BWise

The ultimate concern with spring rate is going to be wheel dynamics in relation the contact patch. Roll is ultimately not a bad thing. As the vehicle rolls you are going to see a camber change at the wheel which will directly relate to the contact patch. A clean sheet design will use this so that the suspension geometry and spring rate are closely matched to utilize the vehicle's dynamics in roll with the variation of the camber curve. A production car will not be optimized for camber change on the track and therefore usually will lose grip with increased roll angle due to the camber characteristics. In this case a stiff roll rate will be a benefit as it will keep the car from extending too far into the poor regions of the camber curve.

That then leads to which is better, stiff springs - soft bars or stiff bars - soft ride springs. That is more dependent than on track surface.

mark kibort

I think its simliar to the discussion in that there are a lot of misconceptions out there regardind set up. I count on the guys I race with to be over sprung to give me an edge . However its always been a little bit of a mystery for me.
What i do know is that spings on one car vs another mean nothing base on the motion ratio. (leverage of the suspension, or in other words, tire movement vs shock movement).
Chris brings up some great points as always. swaybars, etc.

I've always been under the impression that with a soft suspension you can go stiffer on the swaybar to reduce roll. The down side is on high g loading turns, you get "squat" on the inside wheel, which can drop the ride hight up front. But, the extra stiffness of the bar is now independant of the ups and downs of the track, unless you hit a bump on one wheels where that wheel is now effectively more tightly sprung. Im sure there are a handful of dynamics I have yet to even consider. what i do know, is with a soft suspension, when loosen the bar, i do get a lot more body roll that can help with different conditions like rain, or harder tire compounds.

I think its still a very complicated science for which i havent even scratched the surface. with all the control that the shocks can provide, low/high speed bump compression, etc, the variables are endless and so are the tools.

Im scared that If i fix my shocks and get more travel, (as well as stiffening up the springs) i wont be considering the spring rate of the Bump Stops that I've become so dependent over the years on, and it will ruin my game

Note: The above is only based on my experience and no way reflects or coveys any level of expertise on the subject matter of suspension tuning .

Larry Herman

I feel that springs vs sways is more dependent on suspension design. We haven't talked about dive and squat, but most McPherson strut cars do not do a good job managing this, so stiffer springs are necessary to control the fore/aft motions of a McStrut race car, hence softer sway bars!

2BWise

+1

Dive and squat can have dramatic effects and without much anti - dive/squat designed in the easiest way to counter act that is with stiffer ride springs. Another large drawback of large bars is that you've now put a strong couple between opposite sides of the car which will have drastic events in one wheel bump. The other issue is that the roll bar is largely undamped and a stiff bar is will oscillate at a higher frequency.