Looking for some expert advice ie. @CapriRacer
I am coming here because on the C5 forums, everybody is an expert, and the advise is split nearly 50/50...in opposite directions.
I run a 2004 C5 base Corvette manual with the Z51 suspension upgrade and enough power mods to dyno around 400 at the wheels. I run the stock tire size up front, and +20mm width in the back (reduced aspect ratio by 5 to keep stock RR). Stock pressure is 30/30. In bright sunny conditions I usually run 32/32 for AutoX.
I previously raced motorcycles (SV1000S), so my experience has been when I want to increase grip, I lower tire pressure. You do this until you get about a 10% rise in pressure on the track, and are not overheating the tires (getting snotty, or see heat discoloration). I would run between 2-4 psi higher in the front.
My last two runs in the Vette, I was using this logic I gained from motorcycles, and I'm not sure it holds for cars??? So that is my Question.
I experienced a loose rear end (oversteer) in damp and cool conditions, so I lowered my pressures front and rear to 30 psi. I still had a loose tail, so I lowered the rear to 28. I then experienced a lift-off oversteer snap spin. My first spin since my vary fist race in a RWD car. Fast forward to this last race, and it was colder yet...just above freezing. My first run was 30F/28R and I spun again - same lift off, snap oversteer. I lowered the rears down to 27 thinking it was lack of grip in the rear that was giving me the problem. I kept is slower the next several runs, but the rear still felt loose (lack of grip, not wallowing). First run of the afternoon I was still at 27 rear, and it had warmed up, and dang it, I spun again. My confidence was shot, and I basically pooched out my last 3 runs...ugh.
Ok, now I start doing more research, and I am finding papers that say to DECREASE oversteer, especially lift off oversteer, I should INCREASE rear tire pressure. Was I making the condition worse with my old knowledge? When I do forum research I find the camps split about 50/50.
There was no change in tires, alignment, etc. from when the car was performing well at 32/32 as compared to these colder temps. Yes, I realize my tires don't grip as well in the cold, but other folks on the same tires in the same temps using RWD cars were not experiencing the same problem I was. I really think my lowering of the rear pressures was making things worse.
I am coming here because on the C5 forums, everybody is an expert, and the advise is split nearly 50/50...in opposite directions.
I run a 2004 C5 base Corvette manual with the Z51 suspension upgrade and enough power mods to dyno around 400 at the wheels. I run the stock tire size up front, and +20mm width in the back (reduced aspect ratio by 5 to keep stock RR). Stock pressure is 30/30. In bright sunny conditions I usually run 32/32 for AutoX.
I previously raced motorcycles (SV1000S), so my experience has been when I want to increase grip, I lower tire pressure. You do this until you get about a 10% rise in pressure on the track, and are not overheating the tires (getting snotty, or see heat discoloration). I would run between 2-4 psi higher in the front.
My last two runs in the Vette, I was using this logic I gained from motorcycles, and I'm not sure it holds for cars??? So that is my Question.
I experienced a loose rear end (oversteer) in damp and cool conditions, so I lowered my pressures front and rear to 30 psi. I still had a loose tail, so I lowered the rear to 28. I then experienced a lift-off oversteer snap spin. My first spin since my vary fist race in a RWD car. Fast forward to this last race, and it was colder yet...just above freezing. My first run was 30F/28R and I spun again - same lift off, snap oversteer. I lowered the rears down to 27 thinking it was lack of grip in the rear that was giving me the problem. I kept is slower the next several runs, but the rear still felt loose (lack of grip, not wallowing). First run of the afternoon I was still at 27 rear, and it had warmed up, and dang it, I spun again. My confidence was shot, and I basically pooched out my last 3 runs...ugh.
Ok, now I start doing more research, and I am finding papers that say to DECREASE oversteer, especially lift off oversteer, I should INCREASE rear tire pressure. Was I making the condition worse with my old knowledge? When I do forum research I find the camps split about 50/50.
There was no change in tires, alignment, etc. from when the car was performing well at 32/32 as compared to these colder temps. Yes, I realize my tires don't grip as well in the cold, but other folks on the same tires in the same temps using RWD cars were not experiencing the same problem I was. I really think my lowering of the rear pressures was making things worse.