I - 3:15 rear end
Pro
Joined: Sep 2006
Posts: 731
Likes: 9
From: Ivins, Utah
This is what I have (1999):
G90 Axle, Rear, 3.15 Ratio
G92 Performance Axle Ratio 3.15:1 MXO Auto
Are you sure the "I" is not a "1" (the number one) ??
This means 3.15 to 1 (one), it's a ratio, 3.15 turns in to 1 turn out.
Which means, the driveshaft in turns 3.15 times to each 1 turn of the drive axles out.
G90 Axle, Rear, 3.15 Ratio
G92 Performance Axle Ratio 3.15:1 MXO Auto
Are you sure the "I" is not a "1" (the number one) ??
This means 3.15 to 1 (one), it's a ratio, 3.15 turns in to 1 turn out.
Which means, the driveshaft in turns 3.15 times to each 1 turn of the drive axles out.
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
Race Director
Joined: Mar 2007
Posts: 18,308
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From: Marlton. Increasing performance one speeding ticket at a time! NJ
Where did you get the "I" from? The only thing I can think of is Independant, since all these cars have an independant rear suspension.
As was posted above, a gear changes speed. As a result of changing speed, torque is multipled by the same amount. For example, in your automatic transmission, 1st gear is 3.06 and your drive ratio is 3.15, that means a final 1st gear ratio of 9.639. Your engine spinning at 6000RPM (for example) spins the tires at 3000/9.639=622RPM. This translates to a maximum speed in 1st gear of 49mph at 6000RPM. Correspondingly, toque is multiplied by 9.639, so at 6000RPM, if the engine is producing somewhere near 300ft-lbs, it is now producing close to 2900ft-lbs. Since 49mph is the max, sometime the gears switch into 2nd, which I believe is 1.7:1 ratio. Final drive ratio in 2nd is 5.355, with leads to a higher top speed of 88mph, then it will switch into 3rd, etc.
That's why changing the rear gear ratio is so popular. It lowers the tire speed, but increases torque produced at the wheel=more tire spinning fun and better acceleration across the board.
As was posted above, a gear changes speed. As a result of changing speed, torque is multipled by the same amount. For example, in your automatic transmission, 1st gear is 3.06 and your drive ratio is 3.15, that means a final 1st gear ratio of 9.639. Your engine spinning at 6000RPM (for example) spins the tires at 3000/9.639=622RPM. This translates to a maximum speed in 1st gear of 49mph at 6000RPM. Correspondingly, toque is multiplied by 9.639, so at 6000RPM, if the engine is producing somewhere near 300ft-lbs, it is now producing close to 2900ft-lbs. Since 49mph is the max, sometime the gears switch into 2nd, which I believe is 1.7:1 ratio. Final drive ratio in 2nd is 5.355, with leads to a higher top speed of 88mph, then it will switch into 3rd, etc.
That's why changing the rear gear ratio is so popular. It lowers the tire speed, but increases torque produced at the wheel=more tire spinning fun and better acceleration across the board.
