Tristan, if I've not misread anything you've said about your car's handling issues, it's a medium to high speed oversteer issue.
The fact is, rake is a VERY significant contributor to aero balance. Given all else equal and the front end untouched, a small increase in rear ride height of say 5mm would actually generate increases in L/D ratio and front percentage by as much as a few % of difference (very significant). This is based on both CFD and wind-tunnel studies I've seen so far. In fact, increased rake (nose down attitude) is standard procedure for increasing aero efficiency and understeer elimination, especially among front downforce limited cars such as GTs.
Fact of the matter is that with increased front rake the center of pressure actually shifts forward since the angle of both the diffuser and the bottom are increased whilst actually accelerating the front incoming air a bit more. This effectively leads to higher peak airflow velocities, but also allows the air to diffuse and thus decelerate earlier. Hence increased efficiency and front percentage.
In your case , the fact of the matter is that there are still some unknowns I'll like to quantify. Since you said that cranking the rear wings to the max didn't work, I'm also wondering if you have cranked it up TOO much. Having a wing at max angle is usually inefficient since L/D ratio will be compromised. There is also the matter of how airflow over your rear wing is REALLY behaving. Maybe you should get some wool tuffs and a stick on camera or even spread some wax and see how airflow affects them to see what the rear wing is actually doing? Could it be that the rear angle is overdone and the wing could be partially stalling?
I understand that ideally you want to lose none of the front grip you currently have. However, whatever you do to the rear will affect the front some way or the other since everything has knock-on effects in a car.
Some more questions include:
1. Do you have issues with rear grip on slow corners as well?
2. Is this problem significant only at higher speeds?
If answer to Q1 is YES, then start with rear suspension stiffnesses. Try lowering rear ARB stiffness. If that fails as you seem to have indicated then try removing it altogether assuming your rear springs aren't too soft (whereby camber change effects dominate over load sensitivity) in the first place. If this works without generating significant understeer whilst solving your oversteer issue, then great, since missing an ARB is less weight. Unless our weight regulations force a minimum weight but then again you now get to choose WHERE to place it...
If Q1 is no and Q2 is yes, then the logical thing to do is of course lower the rear a bit to shift aero balance to the rear. And yes, lowered rear COG on its own helps with rear tire load distribution, but that must also be balanced with your suspension behavior, which unfortunately remains a mystery without too much detailed technical data. If reasonable rake adjustments fails to achieve any significant improvement, then try tweaking the rear ARB a bit or even stiffening the fronts as long as lower speed balance and tire wear aren't significantly compromised. If that fails THEN tweak the front wings down.
But since you said the tire metrics are good, then maybe you are just unused the handling of the vehicle. try adapting to the oversteer you said about and see if it works. If the oversteer is genuinely at non-optimally large levels then start considering tweaks to wing angle.
The fact is, rake is a VERY significant contributor to aero balance. Given all else equal and the front end untouched, a small increase in rear ride height of say 5mm would actually generate increases in L/D ratio and front percentage by as much as a few % of difference (very significant). This is based on both CFD and wind-tunnel studies I've seen so far. In fact, increased rake (nose down attitude) is standard procedure for increasing aero efficiency and understeer elimination, especially among front downforce limited cars such as GTs.
Fact of the matter is that with increased front rake the center of pressure actually shifts forward since the angle of both the diffuser and the bottom are increased whilst actually accelerating the front incoming air a bit more. This effectively leads to higher peak airflow velocities, but also allows the air to diffuse and thus decelerate earlier. Hence increased efficiency and front percentage.
In your case , the fact of the matter is that there are still some unknowns I'll like to quantify. Since you said that cranking the rear wings to the max didn't work, I'm also wondering if you have cranked it up TOO much. Having a wing at max angle is usually inefficient since L/D ratio will be compromised. There is also the matter of how airflow over your rear wing is REALLY behaving. Maybe you should get some wool tuffs and a stick on camera or even spread some wax and see how airflow affects them to see what the rear wing is actually doing? Could it be that the rear angle is overdone and the wing could be partially stalling?
I understand that ideally you want to lose none of the front grip you currently have. However, whatever you do to the rear will affect the front some way or the other since everything has knock-on effects in a car.
Some more questions include:
1. Do you have issues with rear grip on slow corners as well?
2. Is this problem significant only at higher speeds?
If answer to Q1 is YES, then start with rear suspension stiffnesses. Try lowering rear ARB stiffness. If that fails as you seem to have indicated then try removing it altogether assuming your rear springs aren't too soft (whereby camber change effects dominate over load sensitivity) in the first place. If this works without generating significant understeer whilst solving your oversteer issue, then great, since missing an ARB is less weight. Unless our weight regulations force a minimum weight but then again you now get to choose WHERE to place it...
If Q1 is no and Q2 is yes, then the logical thing to do is of course lower the rear a bit to shift aero balance to the rear. And yes, lowered rear COG on its own helps with rear tire load distribution, but that must also be balanced with your suspension behavior, which unfortunately remains a mystery without too much detailed technical data. If reasonable rake adjustments fails to achieve any significant improvement, then try tweaking the rear ARB a bit or even stiffening the fronts as long as lower speed balance and tire wear aren't significantly compromised. If that fails THEN tweak the front wings down.
But since you said the tire metrics are good, then maybe you are just unused the handling of the vehicle. try adapting to the oversteer you said about and see if it works. If the oversteer is genuinely at non-optimally large levels then start considering tweaks to wing angle.
