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Most everyone with a RAM says 4.56 gears are best for accelerating and shows the best performance gains...

I was just wondering why muscle car owners (mustangs for example) sometimes have 3.55 gears or similar lower number'd gears.

How would the different gears perform at high speeds & also from stand-still acceleration? If I owned a Mustang which gears would be best? If I owned a Ram, which gears would be best?

or does it just depend on what type of racing you'll be doing?
 

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I believe why stangs have 3.55's are because their tires are not tall so its easier to turn them, and the smaller the tire the better the gear gets, with our size tires 30inch to like 32inch the 3.55 are not great because it takes a lot to turn them, when you have 4.56's the tires are easier to turn giving you better off the line,
 

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There are many differences between a car and truck. Mustang vs. Ram for instance.

The diameter of the tire, like said, is a big one. A bigger one is the difference in weight that you trying to push. Then there is aerodynamics.

Our trucks slice through the air at high speeds like a concrete block.

The higher gear gives a mechanical advantage to the drivetrain by reducing the torque at the trans.
 

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Most stangs and F-bodies I see run 4.10's, but anyways look at how much weight they have to get off the line. Close to a ton less. Makes a big difference in gear selection.
 

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Power to weight ratio is also something to consider along with everthing that is mentioned above.

Cars are usually lighter than trucks, so they can use a higher gear with less mechanical advantage because they are using the power of the engine.

Take diesel engines in our trucks for example. They produce around twice as much torque for the same truck. They can use a higher gear because there is plenty of power supplied by the engine. Now the gas engine produces less torque for the same truck so they need some type of advantage to maintain performance. That's where the lower gear will help.

Another example would be to look at the SRT 10 truck. That gas engine produces over 500 ft lb of torque as compared to the 375 ft lb produced by the hemi engine. The SRT 10 can use a higher gear and rely on the torque of the engine for doing work. The hemi engines needs more of a mechanical advantage because of the less power output to maintain performance for the same truck (weight).

Of course there is always a minimum and maximum gear to be run to still provide acceptable driveability.

Higher gear ==> lower numeric number
Lower gear ==> higher numeric number

EDIT:
rock1 posted while I was typing. I am saying the same thing as rock1 only with more detail (maybe too much detail). Hope it helps.
 

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:werd:
 

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Also, they have different transmissions than we do so they have a different 1st, 2nd, etc. gear. The final drive ratio depends on trany ratio, gear ratio and transfer case(if 4x4, splitter etc) ratio. A 727 with 4.56 gears is not the same as a 5-45RFE with 4.56 gears. The 5-45RFE has a 3.0 first gear but the 727 has a 2.45 first gear.
 

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Even the mustangs use different gears from year to year and auto to stick. A 5.0 auto car can get a away with 4.10's or 4.30's, while a stick car is puching it with 3.73's. Also the newer stangs with sticks like the 4.10's better then 3.73's. You dont want to be shifting right before the traps, but you also dont wanna trap at 4500rpm's
 

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NightRunner79 said:
Most everyone with a RAM says 4.56 gears are best for accelerating and shows the best performance gains...

I was just wondering why muscle car owners (mustangs for example) sometimes have 3.55 gears or similar lower number'd gears.

How would the different gears perform at high speeds & also from stand-still acceleration? If I owned a Mustang which gears would be best? If I owned a Ram, which gears would be best?

or does it just depend on what type of racing you'll be doing?
While lower gears will give you a mechanical advantage there is a lot of variables that would make higher gears a better choice. For instance with a higher gear ratio could hold gears longer before shifting, that way you may come in at the 1/4 trap in 2nd gear instead of wasting time having to shift into 3rd whilst being at a lesser power output because your RPM's are lower in 3rd. Which brings me to my next point being your powerband. With lower gears you'll rev right past your powerband quickly and then shift, while higher gears will allow you to hold your rpms a bit longer in your powerband. It all depends on the application really, for a big heavy truck lower gears will help out for the most part.
 
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