Difference in how car is geared???

[Jordansrt]

Looking at 2 cars one is geared 3.31 and the other is geared 3.55. What is the difference in these 2 and why would the 3.55 cost more?

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[Kahboom]

3.55 faster acceleration, 3.31 higher top speed if governor is removed also better mpg with lower gear number so 3.15 best mpg while 3.73 is worst, meanwhile if its supercharged or turbocharged people go for 3.15-3.31 gears, while N/A guys use the steeper gears.

 

[BmacIL]

3.55 faster acceleration, 3.31 higher top speed if governor is removed also better mpg with lower gear number so 3.15 best mpg while 3.73 is worst, meanwhile if its supercharged or turbocharged people go for 3.15-3.31 gears, while N/A guys use the steeper gears.

Technically the lower the number (i.e. 3.15) the steeper/taller the gear ratio, but your point is valid. 3.73 are shorter gears (easier for engine to pull), 3.31 are taller (harder for engine to pull).

 

[jasonstang]

Looking at 2 cars one is geared 3.31 and the other is geared 3.55. What is the difference in these 2 and why would the 3.55 cost more?

The difference is the torque will be reduced less with shorter gears so your rpm will always be in better range for fast acceleration.
The drawback is your fuel economy is gonna drop.

 

[MikeD1]

The cost difference is the $395 Ford adds if you opt for the optional 3.55's.

 

[Cascadia_302]

This^, the only REASON it costs more is because it's classified as an option. Off the shelve the gear sets are priced the same the last time l checked.

 

[mmdpg]

It is probably obvious to most guys here but I recently learned what the numbers mean. 3.15 gears mean the drive shaft turns 3.15 times for every 1 full revolution of the rear wheel. 3.55 turns of the drive shaft for 1 revolution for 3.55 gears. So if you are traveling at a fixed speed, say 60, with the same gear in the transmission, the engine will be turning slower with 3.15 gears than with 3.55 or 3.73 gears. Fewer RPM in the engine should equal better mileage.

 

[EXP Jawa]

The difference is the torque will be reduced less with shorter gears so your rpm will always be in better range for fast acceleration.
The drawback is your fuel economy is gonna drop.

Technically, shorter (higher numeric) gears multiply the torque more. Final drive gears multiply torque and reduce speed of rotation. The shorter they are, the more they do these things. So, with shorter gears, you potentially deliver more torque to the tires - assuming the tires have the traction to absorb it. Thus, quicker acceleration. But, the trade off is you've reduced the potential for overall speed. It also means that the engine is turning proportionally higher RPM for any given road speed.

 

[GTP]

Looking at 2 cars one is geared 3.31 and the other is geared 3.55. What is the difference in these 2 and why would the 3.55 cost more?

The 3.31 comes with the MT6, while the 3.15 comes with the Auto.
You can spend quite a bit of time analyzing all the ratios, because the manual and auto have different ratios for each of the six gears. It is not apples/apples comparison when you include the MT/AT gearboxes.

Anyway, if you are looking to buy an auto, then ask yourself what sort of driving do you do most. If many miles are on the highway, the 3.15 will save you gas. But if you want to maximize 0-60 acceleration, then choose the 3.55.

I don't believe that the 3.55 mpg will suffer in the city with the AT, bc the shift points are so low RPM, that is doesn't make a difference.

OP, are you looking at EB or GT, MT or AT? It gets quite involved keeping everything straight.

[Edit: also there are many gear ratio threads that you can search for.]

 

[15GTBEN]

I love the 3.55's in my GT auto. Definitely feels punchier/quicker than the 3.15 geared 14 auto gt I used to own and 15 gt's I've test driven.

If you are interested in the optional gears, defintely do so from the factory. Getting your gears swap afterwords can be like opening a can of worms, as several issues can arrise. You will also need a tune.

If planning on going forced induction, you will probably be better off with the base gears.

 

[CB]

Difference is .24 to 1

 

[GTP]

...
Getting your gears swap afterwords can be like opening a can of worms, as several issues can arise. You will also need a tune. ...

Care to make a short list here?

 

[HoosierDaddy]

Looking at 2 cars one is geared 3.31 and the other is geared 3.55. What is the difference in these 2 and why would the 3.55 cost more?

Ford charges more because they can. No significant difference in manufacturing costs. Like charging ~$200 MSRP extra for silver paint on PP wheels instead of black. Difference in cost would be insignificant as shown by black and silver paint on the whole the car being the same price.

Ford knows some will want 3.55s so they charge as much extra as they can get away with without making those buyers decide to change them after the sale. It's not a Ford thing. Many makers do it.

 

[Grintch]

The difference is the torque will be reduced less with shorter gears so your rpm will always be in better range for fast acceleration.
The drawback is your fuel economy is gonna drop.

Not always true. With the manual, at 65 mph, a 3.31 gear will provide more acceleration in 2nd than a 3.73 will in 3rd (past the redline in 2nd).

If can can spin the tires easily in 1st, going to a shorter gear isn't going to make you faster. Which is part of why the BOSS 302R racecar has much taller gearing in the first couple of gears than a GT.

Personally I think the 3.31 is the best all around choice. Wish it, or even the 3.55 had been available with the Performance Pack.

 

[craig.martell]

Wish it, or even the 3.55 had been available with the Performance Pack.

This is exactly why I didn't by the Performance Pack. Instead, I bought a base GT with 3.55 gears (settled for the middle way). I then swapped out the suspension for Ford Racing Street Handling Pack -- which gave me slightly better than PP suspension (same as PP except for the springs).

The taller gears, and the lack of the useless center gauges, were what convinced me to go base GT. Why anyone needs to know their vacuum in real time escapes me!

Craig

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