Skidpad?
10-10-02, 10:19 PM
#3
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Two years ago, I looked at an old (1984?) Road & Track review, and I think it said 0.79 or so. I almost laughed out loud in the library!.. most of us could top that in a stock RX-7 if we have skidpad or autocross experience.. or natural ability. 
I wouldn't be surprised at 0.89, with good tires and etc.
I wouldn't be surprised at 0.89, with good tires and etc.
Last edited by genrex; 10-10-02 at 10:23 PM.
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10-11-02, 07:04 AM
#10
Old [Sch|F]ool
Yeah, you have a big flat smooth surface about 200" in diameter or so, and you go around it as fast as possible before the car can't maintain the circle painted on the road. G force can then either be directly measured, or calculated from how quickly you orbit the circle.
There's no transient change at ALL in a skidpad, the only part the suspension plays is how much roll stiffness the car has in the front vs. the rear determining if the car ultimately understeers or oversteers at The Limit steady-state. It pretty much tells you how good the OE tires are.
For example, the only difference suspension-wise between a GSL-SE and a "regular" RX-7 is that the GSL-SE had slightly wider, much grippier tires on it, and differently tuned front strut dampers. That's it. The big increase in grip (.92g i think vs. mid .80's for std RX-7) is entirely due to the tires, since dampers do absolutely nothing in steady state conditions.
Same thing for R1 F vs. base/touring. The R1 had much better skidpad numbers. Only differences were tires, and stiffer shocks... again the spring rates etc were the same.
My gut feeling is that Mazda tinkered with the dampers on both cars because sticky tires and soft shocks are a bad combination, they can force the suspension to move too fast if you drive like a dumbass and it generally feels bad regardless.
Keep all this in mind when ou buy new tires... put some Super Gummy tires on your car (you know, the ones with treadwear ratings around 00 that can allow your car to corner at well WELL over 1g) and you might find that you can maneuver so quickly that you can momentarily bottom the suspension at the exact moment you don't want to...
There's no transient change at ALL in a skidpad, the only part the suspension plays is how much roll stiffness the car has in the front vs. the rear determining if the car ultimately understeers or oversteers at The Limit steady-state. It pretty much tells you how good the OE tires are.
For example, the only difference suspension-wise between a GSL-SE and a "regular" RX-7 is that the GSL-SE had slightly wider, much grippier tires on it, and differently tuned front strut dampers. That's it. The big increase in grip (.92g i think vs. mid .80's for std RX-7) is entirely due to the tires, since dampers do absolutely nothing in steady state conditions.
Same thing for R1 F vs. base/touring. The R1 had much better skidpad numbers. Only differences were tires, and stiffer shocks... again the spring rates etc were the same.
My gut feeling is that Mazda tinkered with the dampers on both cars because sticky tires and soft shocks are a bad combination, they can force the suspension to move too fast if you drive like a dumbass and it generally feels bad regardless.
Keep all this in mind when ou buy new tires... put some Super Gummy tires on your car (you know, the ones with treadwear ratings around 00 that can allow your car to corner at well WELL over 1g) and you might find that you can maneuver so quickly that you can momentarily bottom the suspension at the exact moment you don't want to...
10-11-02, 07:40 AM
#12
Old [Sch|F]ool
No prob.
I find it funny when people brag about their skidpad numbers for a stock car, when they have the cheapest tires that would fit on their rims, usually BFGoodrich's which the street tires are greasy nasty piles of dung...
Also the skidpad numbers are dependent on tire pressure... add or subtract presure and the figures can and will change...
And the skidpad number has nothing to do with handling. A car can handle so bad it's scary to drive, but the skidpad numbers are astronomical. I had a car like that once... I put on Big Huge Tires and dialled in almost 3 degrees of negative camber in the front tires. Did nothing about spring rates, roll centers, bumpsteer, dampers, anything. It'd corner extremely hard (judging by cornering speeds, about the same as my '80 cornered with DOT-R tires on it - better have your seatbelt on TIGHT and you still have to hold yourself up with the seat/door) but the chassis dynamics were worse than appalling - snap understeer, snap oversteer, scary corkscrewing motions if the corner had any bumps at all... that was the only car I ever spun off the road.
I really miss that car....
I find it funny when people brag about their skidpad numbers for a stock car, when they have the cheapest tires that would fit on their rims, usually BFGoodrich's which the street tires are greasy nasty piles of dung...
Also the skidpad numbers are dependent on tire pressure... add or subtract presure and the figures can and will change...
And the skidpad number has nothing to do with handling. A car can handle so bad it's scary to drive, but the skidpad numbers are astronomical. I had a car like that once... I put on Big Huge Tires and dialled in almost 3 degrees of negative camber in the front tires. Did nothing about spring rates, roll centers, bumpsteer, dampers, anything. It'd corner extremely hard (judging by cornering speeds, about the same as my '80 cornered with DOT-R tires on it - better have your seatbelt on TIGHT and you still have to hold yourself up with the seat/door) but the chassis dynamics were worse than appalling - snap understeer, snap oversteer, scary corkscrewing motions if the corner had any bumps at all... that was the only car I ever spun off the road.
I really miss that car....
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