would it be worth neutering my F450 from a 4.88 to a 4.10

The change in rear end gearing will reduce the towing capacity of the truck and may increase wear and tear on the engine and transmission but it is not going to do anything for your fuel economy.

Reducing the speed at which you drive by 10 MPH will help your fuel economy. Reducing the weight of the truck by 1000 lbs. will help your fuel economy. Not towing a trailer will definitely help your fuel economy.

Even with 4-speed transmissions and 4.10 gearing on my SUV's and trucks I got the same MPG as newer vehicles with 5 and 6 speed transmissions. The 5th and 6th speeds are both overdrive gears and more than compensate for the 4.88 gears. When towing the taller 4.10 gears in the F-450 are more likely to hurt fuel economy as the engine will spend more time outside its peak power band.

^^^^^^^ 100% correct and one the money. A+ Marty.

Chris,

At the end of the day, speed will be determined by HP at the flywheel, less drivetrain loss's. So if you have the same motor in a rig with a 9.5" rear diff, vs a 10.5 vs an 11.5. The 11.5 diff will use up more of the motors HP, so it will g slower up a given grade than the one with the 9.5" rear. If the brake drums, calipers etc are smaller on one, that too will get more HP to the ground, so it should be a faster rig up the hill. Put an Allison behind the GM 8.1, and it will be a slower rig up a hill vs the 4l80E trannys, which will be slower than the NV manual trannies, as the allison uses close to 50 hp to run, vs 30-35 for the 4l80 trans vs 20 for the NV.

Lower axel gears will not make up for these loss's. Now if you can not pull say a 20% grade with 4.10's, everything else being equal, a rig with 4.88's may go up the hill, as torque is multipliable. Or the rig with the allison may go up a steeper grade than the 4l80 due to its lower first gear ratio. as will an nv go upa 15% greater hill than an allison and some 20% greater than a 4l80!

Gears help at times, others it is how many HP hit the ground at the wheels. For the OP, 4.10s may be the better option than 4.88's. I find for how I drive, if I can get everything else correct, 4.10s with a typical .75 od and 31" tires is best. 4.33's would work well if I have a typical. .65 dod in the trans, potentially a 4.56 depending upon the motor, rpm it wants to cruise at etc. That is with my typical 60 mph on the interstate driving, be it empty or loaded.

This is like a 28" tired rig with 3.42 gears, will turn the same rpm, shift at the same places as a rig with 30" tires and 3.73 gears, as is a rig with 32" tires and 4.10 gears, If everything else is the same, these rigs will perform about the same.

Marty

blt2ski wrote:
A 4.10 ina 450 will have the SAME pulling power as a 250 or 350 with 4.10's. AS ALL three have the same tire diam. Granted not rim diam, but the tire diam is 31.5-31.75 for ALL of Fords 250-550 trucks. So reality is, gear ratios in the lower, ie 4.88 range will use more fuel. BUT< they do give you more low end grunt to go up steeper initial grades. From a speed perspective, no difference, as that is limited by the HP of the motor, as long as the gear ratio choosen allows the motor to run at is highest HP for the speed. Then it is possible that a 3.73 could be the best ratio!

Would I change out? How much would it cost? and how long will it take to make up the fuel savings? if over 100K miles, and 3 yrs, too much initial cost.

Marty

If the F450 has a large diff, heavier wheels and tires, larger disc brakes etc etc, does that not add to the drive train loses, therefore they use deeper gears for a reason. Or is a F450 just a F350 with deeping gears? That may depend on year?

What is the difference in curb weight? Are they apples and oranges, apples and larger apples or just apples and apples?

Chris

A 4.10 ina 450 will have the SAME pulling power as a 250 or 350 with 4.10's. AS ALL three have the same tire diam. Granted not rim diam, but the tire diam is 31.5-31.75 for ALL of Fords 250-550 trucks. So reality is, gear ratios in the lower, ie 4.88 range will use more fuel. BUT< they do give you more low end grunt to go up steeper initial grades. From a speed perspective, no difference, as that is limited by the HP of the motor, as long as the gear ratio choosen allows the motor to run at is highest HP for the speed. Then it is possible that a 3.73 could be the best ratio!

Would I change out? How much would it cost? and how long will it take to make up the fuel savings? if over 100K miles, and 3 yrs, too much initial cost.

Marty

Compass wrote:
Sorry guys, didn't mean to start an argument...

Nah! You didn't start an argument. It's quite the norm around here. Coffee's ready!:C

I like your idea of just slowing down some. There is no guarantee your mpg will go up significantly plus how long will the payback be.

Sorry guys, didn't mean to start an argument...

Me Again wrote:

Hannibal wrote:

Me Again wrote:

A F450 with tall gears will be a dog. They put low gears in them for a reason. Resell would be in the toilet. So you spend money to screw it up and then loose again to dump it. BTW did you happen to read that OP decided to leave it as is now? Chris

Why would an F450 with 3.55 gear ratio be a dog? A 3.55 ratio in direct drive would be more gear reduction than the 4.88 in O/D. By your assertion, an F350 with 3.31 gears would really be a dog? Unless you're towing max capacity, there's no need to have it howl like a banshee all the time towing or not. That the OP decided to leave as is for now doesn't change the fact that your assertion is false.

What ever. If you had one and wanted to screw up it's towing ability, well it's yours to screw up. OP seems to have seen a light that you have not.

What light? I don't have the otpional 4.30 ratio in my F250 because I don't need it. The 3.73 works perfect. Is my truck screwed up too? When you post any evidence that the F450 needs a 4.88 ratio to tow a 12k lb GVWR 5th wheel, then maybe I too will see the light. As of now, that light's pretty dim. You've attempted to insult my intelligence. Now's your opportunity to enlighten me.

I thought 4.10 was a factory option. Does the drop in tow rating put the OP over?