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cbrookre
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Standard final drive ratio is 3.31 with 3.55 optional, with 3.73 coming with the Performance Package. In general a higher number in the final drive will come with an acceleration advantage, though with a lower top speed and a hit to fuel economy. To what degree each of these is affected by the final drive, I do not have the numbers...
OppoLock
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You've got your final drive ratios listed above. Advantages?
You've got two big things to take into consideration when it comes to gear ratios: keeping your engine in the meat of its power band and fuel economy.
Generally speaking, a shorter final drive (larger, numerically speaking) will lead to quicker acceleration. There are exceptions:
1) Acceleration to certain (and arguably arbitrary) checkpoints like 60mph, or the 1/4 mile might take a split second longer if gearing is shortened to the point that another shift is required.
2) Gearing can be too short to the point that you're missing out on a good chunk of the engine's power band. Hypothetical example: an engine redlines at 7000, and the bulk of its power plateaus from around 5000 to 7000. If you shift from 2nd to 3rd, and it's so short that you go from 7000 to 6000, you're probably being counterproductive by missing out on a useable chunk of the powerband. This is a highly unlikely scenario to be honest. The gear ratio and final drive would be stupidly short.
3) If you track a car, especially a manual, it helps to have gear ratios that are evenly spaced and long enough so that you don't have to shift mid-corner; that can upset the balance and forces you to enter at a higher than optimal gear when setting up for that corner.
Fuel economy shouldn't be too heavily influenced by your choice of final drive. Here are the actual ratios for the manual and auto. They have very long overdrive 6th gears.
You've got two big things to take into consideration when it comes to gear ratios: keeping your engine in the meat of its power band and fuel economy.
Generally speaking, a shorter final drive (larger, numerically speaking) will lead to quicker acceleration. There are exceptions:
1) Acceleration to certain (and arguably arbitrary) checkpoints like 60mph, or the 1/4 mile might take a split second longer if gearing is shortened to the point that another shift is required.
2) Gearing can be too short to the point that you're missing out on a good chunk of the engine's power band. Hypothetical example: an engine redlines at 7000, and the bulk of its power plateaus from around 5000 to 7000. If you shift from 2nd to 3rd, and it's so short that you go from 7000 to 6000, you're probably being counterproductive by missing out on a useable chunk of the powerband. This is a highly unlikely scenario to be honest. The gear ratio and final drive would be stupidly short.
3) If you track a car, especially a manual, it helps to have gear ratios that are evenly spaced and long enough so that you don't have to shift mid-corner; that can upset the balance and forces you to enter at a higher than optimal gear when setting up for that corner.
Fuel economy shouldn't be too heavily influenced by your choice of final drive. Here are the actual ratios for the manual and auto. They have very long overdrive 6th gears.
Yellow15Stang
Well-Known Member
Just noticed something when looking at the gear ratio charts.
The six speed automatic does NOT have a 1:1 ratio in any of the gears.
How will this effect the dyno numbers when trying for a direct comparison between an auto and a manual?
The six speed automatic does NOT have a 1:1 ratio in any of the gears.
How will this effect the dyno numbers when trying for a direct comparison between an auto and a manual?
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OppoLock
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The higher the ratio, the lower the overall dyno numbers. I never understood why though. So if they dynoed a 6AT in 4th with its 1.14:1, it's going to display lower RWHP/RWTQ numbers than a 1:1 4th.
Have fun googling that one.
Grimace427
Well-Known Member
Agree 100%
You don't compare dyno numbers. As long as the dyno runs are consistently done in the same manner(same gear, operator, specs) then you can compare numbers for the same car with different mods and tuning. But there really is no point in comparing dyno numbers between cars. One guy can show 350rwhp and another 385rwhp on another dyno yet they post the same 1/4 mile trap speeds.
I didn't expect it either, but this has been consistently shown when people run their MT-82 cars in 4th gear then again in 5th and show 10-12 more RWHP in 5th. Also changing rear gear ratios to shorter gears(i.e 3.31's to 3.73's) will show less RWHP to the wheels, even though the car will accelerate a bit harder with the shorter gears.
xlover
King of Laserball
what i would do considering the tire diameter and gear ratios are functionally the same as the 11-14 is google some stuff on gearing and speed for those cars. a number of enthusiasts have put together some nice spreadsheets that show at each RPM the theoretical vehicle speed for each of the 3 read end ratios with the MT82. (Hint you might find good info for this topic on the S197 loyalist forum)
Grimace427
Well-Known Member
I use this calculator. http://www.f-body.org/gears/
I went a little further and posted how gear ratios relate to 1/4 mile drag racing.
http://www.fastfordmuscle.com/index.php/topic/192-gears-gears-gears/?hl=gears
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