How much wheel lifiting is too much?
#1
Rennlist Member
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How much wheel lifiting is too much?
Pro photographer is out at our events. I grabbed a bunch of pics of my car and I'm lifiting my inside wheel in lots of corners. The car is a 996 GT3 with revalved OEM Bilsteins on 700#/900# springs.
Question for the set-up gurus: how much lifting is too much? Should I drop to a lower spring rate and/or send the shocks back to redo the rebound? It looks like it might be too slow.
[2 images in sequence]
Note the flying cone!
-td
Question for the set-up gurus: how much lifting is too much? Should I drop to a lower spring rate and/or send the shocks back to redo the rebound? It looks like it might be too slow.
[2 images in sequence]
Note the flying cone!
-td
#2
Rennlist Member
I am pretty interested in the experts thoughts (calling Larry Herman, VR and I am sure others) but a couple of thoughts:
You are running Michelin slicks (correct?) so I assume you have loads of grip.
The pictures, were these from high, low medium, speed corners or some of each?
Are you running stock sway bars and do you have a strut brace?
I do not think the issue is too soft front springs but too soft rears and you probably need beefier sway bars. Of course, you do not want the front/rear spring rate split to get to high so you probably need to go up on spring rates all around.
Lastly, how does the car handle especially between mid corner and track out? Neutral, oversteer. understeer?
Like I said, I am interested in what the experts say...
You are running Michelin slicks (correct?) so I assume you have loads of grip.
The pictures, were these from high, low medium, speed corners or some of each?
Are you running stock sway bars and do you have a strut brace?
I do not think the issue is too soft front springs but too soft rears and you probably need beefier sway bars. Of course, you do not want the front/rear spring rate split to get to high so you probably need to go up on spring rates all around.
Lastly, how does the car handle especially between mid corner and track out? Neutral, oversteer. understeer?
Like I said, I am interested in what the experts say...
#5
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That is an acceptable amount of wheel lift, especially for Hoosier slicks and even more so if the balance of the car is good. It is not likely to be a rebound issue, as the front bar holds the wheel up. If you feel you must get that wheel on the ground, stiffen the springs and/or soften the front bar.
#7
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Donde esta Larry Herman??? Guy has not been seen lately...
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#10
Race Car
That is an acceptable amount of wheel lift, especially for Hoosier slicks and even more so if the balance of the car is good. It is not likely to be a rebound issue, as the front bar holds the wheel up. If you feel you must get that wheel on the ground, stiffen the springs and/or soften the front bar.
1. Soften the front anti-roll bar.
2. Go to softer springs at the front.
3. Stiffen the rear anti-roll bar.
4. Go to stiffer spring at the rear.
If the car is not exhibiting understeer, if you have the balance where you want it, none of those four options is a going to be what you want. They all reduce understeer or increase oversteer.
It all boils down to roll couple distribution (RCD). RCD is the percentage of the total roll resistance provided by each end of the car. It is usually expressed in terms relative to the front suspension. 60 percent RCD means that 60 percent of the roll resistance is provided by the front suspension.
Sometimes, to get the chassis balance you want, the RCD will be imbalanced enough to cause one end of the car to lift a tire off the ground in hard cornering. This could mean there is an inherent imbalance in car configuration. For example, it could mean the rear tires are not wide enough to match the grip provided by the front tires.
Scott
#12
Rennlist Member
I am not sure he needs to. Which is why I asked what the car was doing when it was lifting a wheel. On this particular track (MSR Cresson) many cars, especially 911's, exhibit this. Heck, even my M3 exhibits this on some corners there when I am really hauling the mail. But you wouldn't know it from inside the car, since I (and I suspect TD) am steering with the rear tires...
#13
Race Car
A tire in the air cannot provide any traction. Once a tire is in the air, the axle at the opposite end of the car must deal with all the load transfer. Neither of these is a good thing.
You can't always eliminate wheel lifting, but it is best to eliminate it if you can.
Scott
You can't always eliminate wheel lifting, but it is best to eliminate it if you can.
Scott
#14
Rennlist Member
Well, because of the camber of the track & driving the rear tires, there is no traction to be had, really, from that tire anyway in these corners. Again, that is why I really need to know whether the car is hooked up or not to determine whether he needs to even worry about this. My gut says he does not...