I got a 2001 F250 6.8 V10 with stock 4.30 gears and the MPG are killin me. I'm looking to get new one's but dont know where to look and what kind to get. Any ideas

 

regearing your truck is usualy done to regain lost power (due to lift/bigger tires) you arent gunna see much if any MPG gain by regearing..

what size tires you have now and is the truck stock ???

 

yea it's stock.

 

Do the math. I assume that your truck is 4X4. If so, then you are looking at $500-$600 per axle for new gears. Let's say you pick up 2 MPG with the 3.73 gears... how long would it take to get back the $1000-$1200 expense of the new gears? You will also have less pulling power with the 3.73 gears. If it were my truck, I would not change the 4.30 gears.

 

What do you get fir fuel mileage now?

 

Lots of things can influence your mileage, a lot of which is procedural:

--Tread lightly on the skinny pedal
--Try to find a station that sells straight gas (non E10 gas)
--Make sure your brakes aren't dragging
--Stay below 65mph etc...

Perhaps you need a tune-up??

Like redford asked... what are you getting for MPG now?

I would love to have 4.30's...but i can't justify the expense.

 

If I wasn't in the middle of looking for a house and moving and the funds to have mine pulled, I'd trade you my 3.73's for your 4.30's. Maybe if you wanna do this in a month or so we can work it out.

 

So are 430s better than 410s? I don't do towing except carry loads in bed. I got SD f350 drw

 

Ok, I did the math and based my calculations on the following:

$3.00 - Price per gallon of gasoline
20,000 - Miles driven per year
10 MPG - Current MPG with 4.30 gears
12 MPG - New MPG with 3.73 gears
2 MPG - MPG improvement

20,000 miles per year / current 10 MPG = 2,000 gallons per year

20,000 miles per year / new 12 MPG = 1,667 gallons per year

2,000 gallons per year - 1,667 gallons per year = 333 gallons saved per year

$3.00 price per gallon X 333 gallons saved per year = $1,000

So, if you drive 20,000 miles per year and you can pick-up 2 MPG with the 3.73 gears, at $3.00 per gallon, you can be on the winning end within one year.

 

If you dont plan on doing any kind of towing you could prob get away with 3.55's.

How much highway driving vs city do you actualy do?

 

sorta...
it acutally works out in your favor, because you have to account for gas prices increasing.

if you are getting 10 mpg, then you should change your driving habits not gears.
keep the tach below 2000 rpms at all times.
this simple thing will net you a minimum of 3 mpg and will pay you back.

personally, i have 3.73 gears and find them pretty good for general use, but i dont tow anything at the moment. the most i do is put a bunch of crap in the back and drive up mountains lol.

on that matter, i will say that driving up a mountain (25% grade) with a 5.4 and 3.73 gears is a bit interesting the first time you do it.
the engine was at 3000 rpms in 2nd gear.


the point is that you wont save much MPG by changing gears. it takes a certain amount of torque to drive the truck down the road. either you have more throttle and less rpm or the other way around. in modern fuel injection you dont have to worry so much about rpms as you used to with a carb motor where rpms = pouring gas down the secondaries.


as for the guy who said 3.55, i wouldnt recommend it.
3.73 is pretty tame already. you will feel like you are lugging 1000# in the bed all the time with 3.55 gears

 

Gordon, he does have a V10. Not the underpowered at the time 5.4L.

Alot more torque behind the v10 would allow the 3.55's to be the same or posibly still a little better than your 3.73 5.4L combo.

 

Well, we can figure that out with simple math and do not have to guess at these things.

A 3V 5.4L puts out 365 lb·ft of torque. A 3V V-10 puts out 425 lb·ft. The 5R110W has a 0.712 final overdrive.

So, 365 X 3.73 X .712 = 969.3524 b·ft of torque at the rear wheels for the 5.4L
425 X 3.55 X .712 = 1074.23 b·ft at the rear wheels for the V-10, so yes, a V-10 with 3.55 gears should out-pull a 5.4L with 3.73 gears.

I'll ignore the "underpowered" statement for now, since most have heard my 5.4L speech.

 

thats peak torque values.
what is your off idle torque at normal driving throttle?
regardless of the engine and rear end gearing, it takes a certain amount of torque to accelerate at a certain rate.

lets say you need 80 lb-ft of torque to accelerate away from a stop light in an empty truck.
if you have bigger number gears, then you will achieve that torque with less throttle.
smaller number gears will need more pedal to get going.

i understand what you are saying about the v10 being more powerful and therefore ok with less gear.
the math may make you feel better, but i can tell you from personal experience that driving a car with too little gear is not fun, regardless of what the math says.

try driving a 3600 lb car with 2.73 gears, 2.52:1 first gear, and 30" tall tires.
i dont care what engine you have, its going to feel like a dog.
the car in question was fine once you got up to speed, and turned 1500 rpms at 70 mph, but it wouldnt get out of its own way around town.


its your truck, and if you want 3.55 gears, then go for it. put your gears on ebay and you will make back some dough.
i just personally wouldnt do it.
you asked for advice and thats my advice.



i'll say it again.
if you want better mileage, change your driving.
10 mpg is horrendous for an empty super duty.
keep your rpms below 2000, and come back after a tank of gas.
if you can change your driving habits and get up to 16 mpg, and still want the gears, then go for it.
i highly doubt though that re-gearing, assuming you drive the same after the new gears, will get you even 1 mpg difference, unless you do 90% highway driving.

 

I dont see a v10 getting that good of milage unless you putt around so slow you end up pissing off old people in towncars.

I cant find the info right this min but on this model year v10 isnt the peak torque in the mid 2000rpm range?