My GT3 is frustrating
01-12-2016, 11:04 AM
#31
Tried. Just ended up a lot slower.
On a side note: The myth of slow is fast is mostly applicable to beginners (not saying I'm advance or anything) learning, but if you constantly stay at 98% you will never get faster. There is a "Goldy Locks Zone" of 106 - 110% is where the car is the fastest. Ask any fast guy and this is what he will tell you, anything beyond or below that threshold is slow. But always keeping it in that zone is the hard part, and this what the perfect lap is (if there is such a thing).
Good comments and discussion. To some extent, I think that behavior is inherent in this car (there are similar reports for the RS), so we need to adapt our inputs to keep the car stable, especially at corner entry. Not sure how much you're trailbraking, but you might try initiating braking earlier and doing less trailbraking, along with recalibrating your steering input so that the weight 'rolls' from the front to the side of the car at corner entry more smoothly and with more optimal timing. The rear stepping out too quickly can be indicative of not enough weight back there and/or rate of steering input being too high. Tracks also make a difference. I find that the rear of the car wants to step out much more quickly in some turns of some tracks vs others. Pavement surface texture, track geometry, bumps, etc. can make a big difference. But as others have said, do also make sure nothing's wrong with the setup of the car. Maybe recheck the alignment, make sure nothing's loose, etc. Hopefully, you don't have something like a bad damper. Your tire pressures seem reasonable; you can certainly tweak them, but I'm guessing that they aren't off enough to be a major factor in what you're experiencing.
All very valid remarks Manifold. It seems that the car can take some slip angle of I'm not mistaken, but when it judders, it just goes, and the grip is very unpredictable when it comes back, making it very hard to gauge how much steering input is needed to correct the attitude of the car. I wonder if someone can recalibrate the diff since it's an electronic diff to lock more aggressively on the overrun, that way, the back end can be a little more predictable plus it gives a bit more push at turn in. I think the car needs it, it tends to be loose on entry.
On a side note: The myth of slow is fast is mostly applicable to beginners (not saying I'm advance or anything) learning, but if you constantly stay at 98% you will never get faster. There is a "Goldy Locks Zone" of 106 - 110% is where the car is the fastest. Ask any fast guy and this is what he will tell you, anything beyond or below that threshold is slow. But always keeping it in that zone is the hard part, and this what the perfect lap is (if there is such a thing).
Good comments and discussion. To some extent, I think that behavior is inherent in this car (there are similar reports for the RS), so we need to adapt our inputs to keep the car stable, especially at corner entry. Not sure how much you're trailbraking, but you might try initiating braking earlier and doing less trailbraking, along with recalibrating your steering input so that the weight 'rolls' from the front to the side of the car at corner entry more smoothly and with more optimal timing. The rear stepping out too quickly can be indicative of not enough weight back there and/or rate of steering input being too high. Tracks also make a difference. I find that the rear of the car wants to step out much more quickly in some turns of some tracks vs others. Pavement surface texture, track geometry, bumps, etc. can make a big difference. But as others have said, do also make sure nothing's wrong with the setup of the car. Maybe recheck the alignment, make sure nothing's loose, etc. Hopefully, you don't have something like a bad damper. Your tire pressures seem reasonable; you can certainly tweak them, but I'm guessing that they aren't off enough to be a major factor in what you're experiencing.
All very valid remarks Manifold. It seems that the car can take some slip angle of I'm not mistaken, but when it judders, it just goes, and the grip is very unpredictable when it comes back, making it very hard to gauge how much steering input is needed to correct the attitude of the car. I wonder if someone can recalibrate the diff since it's an electronic diff to lock more aggressively on the overrun, that way, the back end can be a little more predictable plus it gives a bit more push at turn in. I think the car needs it, it tends to be loose on entry.
01-12-2016, 11:40 AM
#32
This may sound strange to some based on what I've read but hot pressures on psc2's are fine up to 50 psi. This comes from the techs in Birmingham.
I used to run 36/39 hot, f/r, but now I let 'em run to 44 hot.
Sidewalls need pressure for stability. It will improve turn in. And if you want to slide, drop tears below fronts et voila...
Try it.
I used to run 36/39 hot, f/r, but now I let 'em run to 44 hot.
Sidewalls need pressure for stability. It will improve turn in. And if you want to slide, drop tears below fronts et voila...
Try it.
01-12-2016, 11:43 AM
#34
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All very valid remarks Manifold. It seems that the car can take some slip angle of I'm not mistaken, but when it judders, it just goes, and the grip is very unpredictable when it comes back, making it very hard to gauge how much steering input is needed to correct the attitude of the car. I wonder if someone can recalibrate the diff since it's an electronic diff to lock more aggressively on the overrun, that way, the back end can be a little more predictable plus it gives a bit more push at turn in. I think the car needs it, it tends to be loose on entry.
The car seems to be quite sensitive to setup adjustments, so a little tweaking may soon get it to a point where you like it.
Personally, I wouldn't consider messing with the diff, since a lot of engineering went into making the diff, torque vectoring, RWS, etc. work together well, so changes to the 'do not touch' parts of the car may wreak havoc.
01-23-2016, 09:35 PM
#35
Rennlist Member
Interesting. Cup 2's are oem but Trofeo R's can void the warranty, even though they aren't slicks?
01-23-2016, 10:05 PM
#36
01-24-2016, 09:06 AM
#38
So I tried different pressures this past weekend, and the car behaved much better. I deflated my tires to 33/36 in an open session (not in the vid) and had a few moments with some rotation on entry and the car didn't judder at all. Then went out as lead car for another group and tire pressures came down, then parked the car. When I went back out in an open session (in the video above) tire pressures started at 29/33 cold. After bringing the tires up to temp, pressures were 32/35 hot without touching them. I didn't get any judder accept the last corner (shown in the end of the vid) where the car had a moment of turn in rotation. There was a slight judder but it was very imperceptible although it's very evident in the vid. Might have been a high frequency judder. In any case, the car felt better. Arth and I are lapping very similar times and he runs 31/31 pressures and says car feels fine...
01-24-2016, 10:23 AM
#39
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Based on my track experience, I'd speculate that starting 29/33 cold is still too high. I'm hardly an expert so take my advise with a grain of salt. However the experts at the track with whom I interact have guided me to a cold temp of mid 20's so as to get around 30 hot. That works quite well for me. My track tires are Hoosier R6's, so different tires may perform differently than mine at these particular pressures.
01-24-2016, 12:57 PM
#40
Yas Marina 22 Jan 2016 - YouTube
So I tried different pressures this past weekend, and the car behaved much better. I deflated my tires to 33/36 in an open session (not in the vid) and had a few moments with some rotation on entry and the car didn't judder at all. Then went out as lead car for another group and tire pressures came down, then parked the car. When I went back out in an open session (in the video above) tire pressures started at 29/33 cold. After bringing the tires up to temp, pressures were 32/35 hot without touching them. I didn't get any judder accept the last corner (shown in the end of the vid) where the car had a moment of turn in rotation. There was a slight judder but it was very imperceptible although it's very evident in the vid. Might have been a high frequency judder. In any case, the car felt better. Arth and I are lapping very similar times and he runs 31/31 pressures and says car feels fine...
So I tried different pressures this past weekend, and the car behaved much better. I deflated my tires to 33/36 in an open session (not in the vid) and had a few moments with some rotation on entry and the car didn't judder at all. Then went out as lead car for another group and tire pressures came down, then parked the car. When I went back out in an open session (in the video above) tire pressures started at 29/33 cold. After bringing the tires up to temp, pressures were 32/35 hot without touching them. I didn't get any judder accept the last corner (shown in the end of the vid) where the car had a moment of turn in rotation. There was a slight judder but it was very imperceptible although it's very evident in the vid. Might have been a high frequency judder. In any case, the car felt better. Arth and I are lapping very similar times and he runs 31/31 pressures and says car feels fine...
01-24-2016, 03:32 PM
#41
Sounds better, you're getting closer. Give my above Sugestions a try, I should add it was talking to randy pobst when he was tracking a gt3 at one of my track days that I stopped listening to many of the key board warriors and went with higher pressures that he suggested and were in line with Michelin's as well. The car should feel VERY predictable, I've been all kinds of sideways ect and there is nothing unpredictable at all, and it's incredibly easy to feel it coming on and correct for it.
01-24-2016, 03:34 PM
#42
Based on my track experience, I'd speculate that starting 29/33 cold is still too high. I'm hardly an expert so take my advise with a grain of salt. However the experts at the track with whom I interact have guided me to a cold temp of mid 20's so as to get around 30 hot. That works quite well for me. My track tires are Hoosier R6's, so different tires may perform differently than mine at these particular pressures.
