3.5:1 gearing in 1st gear compared to 3.3:1, what are differences?
08-09-2001, 10:14 AM
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3.5:1 gearing in 1st gear compared to 3.3:1, what are differences?
One is gearing on a 1.8T A4 the other on a Golf 1.8T. Which accelerates faster? Why? Any info about gear ratios would be great, I'm trying to learn.. Thanks
Brett
Brett
08-09-2001, 10:42 AM
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Lower ratio (higher numerically) will provide crisper off the line acceleration....
whilst a higher gear (lower numerically) will provide less off the line punch but you will be able to achieve a higher speed in that gear.
08-09-2001, 10:47 AM
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Everything else being equal, the 3.5:1 ratio in 1st gear would accelerate faster............
Here's the difference:
* 3.5:1 1st gear ratio
At an engine RPM of 4000, the transmission output shaft would be spinning at 4000 / 3.5 = 1143 RPM
* 3.3:1 1st gear ratio
At an engine RPM of 4000, the transmission output shaft would be spinning at 4000 / 3.3 = 1212 RPM
Now you're probably wondering, "Didn't he just say the 3.5:1 ratio would accelerate faster...?" Here's the catch. A larger diameter gear can more easily turn its adjacent gear than can a smaller diameter gear. The former may take more turns to achieve the same speed, but the effort exerted seems to be less. The 3.5:1 ratio can spin the driveshaft up and down faster than can the 3.3:1 gear. The downside is that the 3.5:1 1st gear will have a lower maximum speed at your engine's redline.
It's just like the gears on a bicycle. It's much easier to use a large 1st gear to pedal up a hill. You pedal a lot more revolutions, but it is easier to get going.
* 3.5:1 1st gear ratio
At an engine RPM of 4000, the transmission output shaft would be spinning at 4000 / 3.5 = 1143 RPM
* 3.3:1 1st gear ratio
At an engine RPM of 4000, the transmission output shaft would be spinning at 4000 / 3.3 = 1212 RPM
Now you're probably wondering, "Didn't he just say the 3.5:1 ratio would accelerate faster...?" Here's the catch. A larger diameter gear can more easily turn its adjacent gear than can a smaller diameter gear. The former may take more turns to achieve the same speed, but the effort exerted seems to be less. The 3.5:1 ratio can spin the driveshaft up and down faster than can the 3.3:1 gear. The downside is that the 3.5:1 1st gear will have a lower maximum speed at your engine's redline.
It's just like the gears on a bicycle. It's much easier to use a large 1st gear to pedal up a hill. You pedal a lot more revolutions, but it is easier to get going.
08-09-2001, 10:55 AM
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Nitpicking, but a higher ratio in this case IS higher numerically..........
3.5 to 1 is a higher ratio than 3.3 to 1
It doesn't make sense to say that 3.5 to 1 is a not a higher ratio, but that it's higher numerically. It is both.
It doesn't make sense to say that 3.5 to 1 is a not a higher ratio, but that it's higher numerically. It is both.
08-09-2001, 01:28 PM
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You're right.......
you are nitpicking 
BTW, this is how it was explained in Mustangs and Fords, I think 9/99 issue (only reason I know is my car was in that issue - got it memorized). There is some argument in there that convinced me, but I don't want to get into it. Consider me the Kofi Annan of AW.
BTW, this is how it was explained in Mustangs and Fords, I think 9/99 issue (only reason I know is my car was in that issue - got it memorized). There is some argument in there that convinced me, but I don't want to get into it. Consider me the Kofi Annan of AW.
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