GT3RS Understeer Cured (and how)
#61
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This weekend I tried real cups I.e. 18 inches. With the setup I used to dial out the understeer with the oem tires the car was evil with oversteer. I played with the sway bars to no avail. I need a different setup!
#62
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now it's a slight push, bars are full soft front, full stiff rear.
2.1/2.5 camber
#63
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Bob,
what size MPSC were you running? I have tried 315 rear, 235 front and the car was understeering like crazy. I have -2 degrees of camber front and back and run full soft in the front and full hard in the back.
How do they compare to other tires you tried?
Thanks,
Stephan
what size MPSC were you running? I have tried 315 rear, 235 front and the car was understeering like crazy. I have -2 degrees of camber front and back and run full soft in the front and full hard in the back.
How do they compare to other tires you tried?
Thanks,
Stephan
#64
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Stephan - withe the 19 in OEM tires I had massive understeer. I corrected it by going neg 2.5 in frnt, neg 2 in back, 0 front toe and 16 mins per side in back. Bars full soft F and full stiff R. This made the car pleasant to drive on track.
When I put on the 18 in. cups, 235F 315 rear, I had a LOT of oversteer. I played with the bars going full soft in back - not much improvement. The front end turned in like it was laser guided but the back end would go loose even in the easiest turns. In desperation, I went full stiff in front. Bad idea! I had understeer and when I managed to get the car turned in, the back slid out. Evil handling to say the least. NOTE this assumes that my alignment was the way I had set it. Who knows maybe it got knocked out and I have toe oout in back without knowing. Something is weird for sure. I went back to my OEM tires for the rest of the event.
I will try a new setup for the cups, I am figuring neg 2.2 in front and 2.5 in back. Bars more neutral. I'll report. If anyone has a killer setup for the RS nd 18 inch cups, let me know!
When I put on the 18 in. cups, 235F 315 rear, I had a LOT of oversteer. I played with the bars going full soft in back - not much improvement. The front end turned in like it was laser guided but the back end would go loose even in the easiest turns. In desperation, I went full stiff in front. Bad idea! I had understeer and when I managed to get the car turned in, the back slid out. Evil handling to say the least. NOTE this assumes that my alignment was the way I had set it. Who knows maybe it got knocked out and I have toe oout in back without knowing. Something is weird for sure. I went back to my OEM tires for the rest of the event.
I will try a new setup for the cups, I am figuring neg 2.2 in front and 2.5 in back. Bars more neutral. I'll report. If anyone has a killer setup for the RS nd 18 inch cups, let me know!
#65
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Stay with as much neg up front as you can and try to balance that setting in the rear. Instead of going from full soft to full stiff up front, try going to the middle up front. You might also try going 1 off full stiff in the rear, but the spring rate back there really requires a full stiff rear bar. The 18's are the right idea, don't give up and keep trying, you'll get there.
Another idea.... try 295's in the rear, or 245's up front to get a more equal footing.....
Another idea.... try 295's in the rear, or 245's up front to get a more equal footing.....
#67
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Colm - we are thinking alike. I have a date with Jean Francois Dumoulin - he has 4 Rolex watches on his arm - 4x Daytona 24 Hrs winner in Porsches.
Best,
Best,
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I'm just teasing you Bob!!
Did you book him on Bob's day?
#69
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Bob, I thought it was only 2 Rolex's 2007 and 2005 but I may be mistaken. Good idea tho' especially if you fancy a trip down the 401 to see Perry's buddy Johnny (Giacomo) with 30K in your pocket. Let me know how it works out
CWay27,
I saw your car in the paddock last weekend ...it's still for sale! I would have thought that someone would have snapped it up.
CWay27,
I saw your car in the paddock last weekend ...it's still for sale! I would have thought that someone would have snapped it up.
#70
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Hello all RS experts,
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
#71
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Hello all RS experts,
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
john at CCW said his C14 18" wheel will clear, but i didn't follow up as i dont have PCCB.
#73
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Hello all RS experts,
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
I`am a german owner of a 997 GT3 RS in green and with PCCB and need your advice: I read that the track and sport use of the car would be much better when using 18 inch wheels (with MPSC, Hoosiers or Toyo R1 sizes 235/245/255 front and 305/315 rear on rims sizes 8,5/9 front and 12 rear) in stead of the 19 inch wheels. 19 inch tires do not bring the dry performance of the 18 inch sport tires. My question is: Is it possible to fix and drive 18 inch rims on a 997 RS with PCCB without damaging the brake?
As I understand this is no problem on the rear axle, but on the front axle (regarding the wide PCCB calipers on the front, wider than the steel version).
If it is possible, what rims ( exact sizes and ET/wheel offset rear and front) are recommended (Fikse FM10 or CCW C14 or whatelse)?
Kind regards and thanks for your help! Dieter
Most forum members are still guessing and experimenting.