Stiff springs - more or less grip?
#31
Rennlist Member
#32
Nordschleife Master
Lowering the center of gravity leads to less body roll, putting even less demand on the springs in the first place (i.e. the effect is not linear).
#33
Three Wheelin'
Seeing as how Kibort got everyone torqued out of shape on the HP thread, I figured it was my turn to start up a suspension squabble.
The basic premise is simple - Do stiffer springs offer more grip, less grip, or both, depending on the circumstances?
My feeling is that on smoother surfaces, stiffer springs offer more grip because the car leans less and the tire contact patch stays at a more optimal shape. On a rougher track, grip suffers because the stiffer springs load and unload more quickly, causing a larger variation in grip than with softer springs that track better. All this assumes that your shock settings are optimized for the conditions.
Your well-thought out opinions and experiences are appreciated. Knee-jerk reactions and regurgitation of dogma will be dealt with Rennlist style.
The basic premise is simple - Do stiffer springs offer more grip, less grip, or both, depending on the circumstances?
My feeling is that on smoother surfaces, stiffer springs offer more grip because the car leans less and the tire contact patch stays at a more optimal shape. On a rougher track, grip suffers because the stiffer springs load and unload more quickly, causing a larger variation in grip than with softer springs that track better. All this assumes that your shock settings are optimized for the conditions.
Your well-thought out opinions and experiences are appreciated. Knee-jerk reactions and regurgitation of dogma will be dealt with Rennlist style.
Yes.
No.
Should I use stiffer springs when using center lock wheels?
#35
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Saw that one coming.
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Larry Herman
2016 Ford Transit Connect Titanium LWB
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Past Flames:
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
#36
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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.
Do you start from stratch or from the baseline.
#37
Three Wheelin'
#38
Rennlist Member
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.
Do you start from stratch or from the baseline.
#39
Those should also cure a bit of the lack of driver comfort you mentioned.
My untested opinion is that on a 'normal' Porsche GT car, stiff (>1500lb/in with dual or progressive rate) springs are faster in all conditions (provided that modern GT tires are being used) and faster yet on bumpy tracks. They however do provide less driver comfort and not everyone likes that. Ultimately driver comfort is a larger factor than suspension performance.
#41
Rennlist Member
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
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
#42
Three Wheelin'
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.
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.
#43
Rennlist Member
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 .
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 .
Seeing as how Kibort got everyone torqued out of shape on the HP thread, I figured it was my turn to start up a suspension squabble.
The basic premise is simple - Do stiffer springs offer more grip, less grip, or both, depending on the circumstances?
My feeling is that on smoother surfaces, stiffer springs offer more grip because the car leans less and the tire contact patch stays at a more optimal shape. On a rougher track, grip suffers because the stiffer springs load and unload more quickly, causing a larger variation in grip than with softer springs that track better. All this assumes that your shock settings are optimized for the conditions.
Your well-thought out opinions and experiences are appreciated. Knee-jerk reactions and regurgitation of dogma will be dealt with Rennlist style.
The basic premise is simple - Do stiffer springs offer more grip, less grip, or both, depending on the circumstances?
My feeling is that on smoother surfaces, stiffer springs offer more grip because the car leans less and the tire contact patch stays at a more optimal shape. On a rougher track, grip suffers because the stiffer springs load and unload more quickly, causing a larger variation in grip than with softer springs that track better. All this assumes that your shock settings are optimized for the conditions.
Your well-thought out opinions and experiences are appreciated. Knee-jerk reactions and regurgitation of dogma will be dealt with Rennlist style.
#44
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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!
#45
Three Wheelin'
+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.
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.