Original message:
>At 10:18 AM 9/9/99 -0400, you wrote:
>Just checking out the Dodge web site and was curious. You have a choice
>now of either the standard 3.92, or the 3.55 at a $40 option. Now,
>could maybe the 3.55 do well in 1/4 racing because there would be
>less chance of traction loss off the line and more potential top-end MPH?
> <snip> Jack Hilton III
1st Reply:
>It's the other way around...the 3.92 would give better traction since the
>torque transfer isn't as high. Easy to explain:
>Take a 10-Speed. Stick it in 1st gear and you'll take off like a
>champ. Stick it in 3rd or 4th and it's a little harder to take off...and,
>most of the time, the rear wheel breaks loose - traction loss.
>If you're looking for 1/4 mile performance, stick with the 3.90's. If you
>looking for a "Highway Cruiser", stick with the 3.55's. - Bernd
2nd Reply:
>I don't know anything about 1/4 mile times, but I think Jack was right the
>first time. If you're ever going to break loose, in a ten-speed or
>otherwise, its going to be in the lowest gear (highest ratio). <snip> - Jay
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The torque multiplication provided by your axle gears is torque generated
by the engine times the gear ratio (at any one instant). As an example,
assume that the engine and transmission are delivering 100 lb-ft of torque
to the pinion gear. If the gear ratio is 3.92:1 then the output torque
is 100x3.92= 392. With the 3.55:1, the output torque is 100x3.55= 355.
The lower 3.92:1 gears put more power to the ground than the higher 3.55:1
gears bearing in mind that the engine's power has not changed but that the
available torque to the tires has. Considering that lower gears (3.92)
provide greater torque multiplication, it more likely that traction will
be a problem off the line.
More often than not, typical street machines generally run quickest with lower
gears (3.92) on the dragstrip but there are other factors which can make using
higher gears (3.55) the exception to the rule e.g. if the engine has gobs of
low-end torque and doesn't like to spin at high rpm or/and if nitrous is used.
Bob, Burlington, Ontario
'97 FR CC NSV Sport, 5.2L, 3.55 SG, auto.
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