Breakdown of Different Gear Options/Ratios for super duties

[TX_TRU_STUD]

Hi Guys,

Can someone breakdown and explain the different gearing options for the super duties including best use scenario, mileage, top speed, torque, etc.?

[mufflerbearing]

The gear ratios for the Ford Super Duty trucks are 3.31, 3.55, 3.73, 4.10, 4.30. I am not absoutely sure of the 4.10/4.11, but is has been a good and common ratio for ever.

The smaller the number, the better the mileage with these diesels. The bigger the number, the more that the truck will pull. The axle ratio choices are vast because of the vast use of the vehicles they are put into. The F250 and the F350 non dually can have the 3.31 gears. The dually can get the 3.73, but not sure if the 3.55's are available. The F450 only gets the 4.30 gears.

I guess the real question is what will you be doing with your truck?

[bigcountrysg]

The two common are 3.73:1 and 4.10:

3.73:1 is 3.73 revolutions of the driveshaft to 1 turn of the ring gear.

4.10:1 is 4.10 revolutions of the driveshaft to 1 turn of the ring gear.


There are limited slip differentials, open differentials and locked differentials.

These are the common rear axles for the super duties from 99-03. After that I am not sure what was offered because I own an 02.

Now depending on tire size, driving conditions and all that. The lower the gear ratio the better fuel mileage you will get.

The higher gear ratio the quicker acceleration you get but lower fuel mileage.

As for fuel economy you want a lower gear ratio. This will keep your rpm's down, for top speed well they will all have the same top speed just depends on how quick you want to reach it.

[knotcher]

those are the old ratios. The SRW have newer rearend ratios.

This is a hugely misunderstood topic.

[31 YNOT]

For the new 6.7L trucks with a single rear wheel(SRW) you have the choice of 3.31 gears or 3.55 gears.

For dual rear wheel f-350's you can get 3.73's gears

F-450's come with 4.30 gears.


The point of gearing is to find a happy medium between fuel milage and towing power(torque).

The lower number gears such as a 3.31 will net you better fuel milage because the drive shaft turns 3.31 times for each turn of the tires vs something like a 4.30 gear which the drive shaft will turn 4.30 times for each time the wheels make a rotation. Thus with the 3.31 gears the engine will be turning at a lower RPM at the same mph vs the 4.30 gears.

On the other hand a 4.30 gear will increase torque to the rear wheels for starting off with very heavy weights. The truck will have a much easier time being able to pull a heavy load such as 25K lbs than a truck with a 3.31 ratio

The trick is finding which is the best combo for what you plan on doing. Most guys will not need the 4.xx gears with the power that these new trucks make

Hope this helps if not try reading up here
HowStuffWorks "How Gear Ratios Work"

[Lead Foot]

Originally Posted by knotcher

those are the old ratios. The SRW have newer rearend ratios.

This is a hugely misunderstood topic.

What They listed is Correct except the 4.10 I don't see it listed.....

For 2010/11/12 You have:

3.31
3.55
3.73
4.30

3.31 and 3.55 are for F250/350 SRW ONLY!

3.73 and 4.30 you can get in DRW OR Gasser

If you Don't pull much the 3.31 is the way to Go...

IF you tow or Plan to lift the truck i would go with the 3.55's

You will loose around 3 to 4 MPG when you lift it,before you even ask This is Stock! you can mod it with the Deletes and H&S Tunner and get some of this back even more in some cases Your truck will very as No two trucks are the same!

[mogle]

my 97 gasser has 4.10 gears i know it does since had to replace the axle after i snaped it pulling trees out of ditch

[jesilvas]

Originally Posted by mogle

my 97 gasser has 4.10 gears i know it does since had to replace the axle after i snaped it pulling trees out of ditch

Entirely possible, but the 2011+ trucks are different.
though.

Btw, very old thread.

[BIG Laing]

Originally Posted by mogle

my 97 gasser has 4.10 gears i know it does since had to replace the axle after i snaped it pulling trees out of ditch

Holy thread revival! Good job FNG..