Ring and pinion change for MPG
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New User
Joined: Sep 2006
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Ring and pinion change for MPG
Have a 03 F-250 Crew Cab 4X4 5.4L
I'm looking at several ways to increase MPG thinking of changing from 4.10 to 3.73 gears. I only get 12MPG and understand that if I change the gears I could get maybe in the 16's, I may see a return in about 2 Yrs. Also looking at a MPFI spacer, I understand I could gain some MPG that way. I also here that going for the exhaust tuning only gives the power and sound no MPG savings. I do some towing of a RV trailer but would give up the pulling power for the mileage. I'm open for suggestions, ideas, advice, ETC. HELP!! Thanks to anyone.
I'm looking at several ways to increase MPG thinking of changing from 4.10 to 3.73 gears. I only get 12MPG and understand that if I change the gears I could get maybe in the 16's, I may see a return in about 2 Yrs. Also looking at a MPFI spacer, I understand I could gain some MPG that way. I also here that going for the exhaust tuning only gives the power and sound no MPG savings. I do some towing of a RV trailer but would give up the pulling power for the mileage. I'm open for suggestions, ideas, advice, ETC. HELP!! Thanks to anyone.
Lead Driver
Joined: Sep 2003
Posts: 5,844
Likes: 5
From: Albuquerque
IMHO...live with the 12mpg...and keep the 4.10 gears. Going backwords to the 3.73s is a waste of $$$. It will cost about $1500-$2200 for the change (both axles)...and that will buy a lot of gas.
The 5.4L in a CC 4x4 setup really needs the 4.10s at a minimum...especially if you are going to tow anything over 5k lbs.
Did not mention how many miles you have? Do you keep with the FORD recommended maintenance schedule? That is "KEY" to getting in the 14-15mpg range for highway driving.
biz
The 5.4L in a CC 4x4 setup really needs the 4.10s at a minimum...especially if you are going to tow anything over 5k lbs.
Did not mention how many miles you have? Do you keep with the FORD recommended maintenance schedule? That is "KEY" to getting in the 14-15mpg range for highway driving.
biz
Mountain Pass
Joined: Jan 2003
Posts: 226
Likes: 12
I used to have a '89 Bronco that had a 302 and 3.55 gears. I switched it to 4.10 gears and saw absolutely no change in my MPG. I made that switch for an entirely different reason, but was watching closely to see how bad the mileage was going to get. I would say stay with the 4.10s, you won't see much difference in RPM anyway just going from 4.10 to 3.73.
As far as the spacers go, I have heard nothing positive about them, do a search on this site and see what other's have experienced with them. I think that adding a few inches to the intake runners might make a difference, but don't see it doing much at the throttle body. Biz hit it on the head, keep it properly maintained for the best mileage.
As far as the spacers go, I have heard nothing positive about them, do a search on this site and see what other's have experienced with them. I think that adding a few inches to the intake runners might make a difference, but don't see it doing much at the throttle body. Biz hit it on the head, keep it properly maintained for the best mileage.
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I stay with fords recommedations even use the FOMOCO oil (5w-20 synthetic blend) and replaced the worn tires with OEM firestones. I have 41k on the odometer and only get 12 maybe 13 highway If I tow I only get in the 9's. Had the local ford dealer check the MPG when it was warranted, all they said was the computer shows 12 MPG it may get better after it breaks in.That was 30 k ago. As to the cost of the gears at the local 4X4 shop is only $850 and I can do the set-up mayself.
Postmaster
Joined: Dec 2003
Posts: 4,196
Likes: 10
From: Arizona
pappyross,
I have to agree with the others, you are wasting your time and money, you have a 4x4 truck that weighs around 6-7000 lbs and you expect good gas mileage. Its not going to happen. The percentage change between the 4.10 and 3.73 gears is so small that you will not see it in terms of gas mileage, you will only drop your RPM's by about 200 at 60MPH cruising down the road, at best you might pick up 1 mile per gallon and even if you do that it will take a long time to pay for the cost of the gears. Additionally your towing ability will drop substantially due to the higher gears.
My 2002 Expedtion with the 5.4L never got better than 14MPG and that included highway miles, and it didn't weigh what the SD does.
So IMHO changing your gearing is just throwing away good money. If you really need better gas mileage then get a smaller liter truck in 2 wheel drive.
Just my .02
I have to agree with the others, you are wasting your time and money, you have a 4x4 truck that weighs around 6-7000 lbs and you expect good gas mileage. Its not going to happen. The percentage change between the 4.10 and 3.73 gears is so small that you will not see it in terms of gas mileage, you will only drop your RPM's by about 200 at 60MPH cruising down the road, at best you might pick up 1 mile per gallon and even if you do that it will take a long time to pay for the cost of the gears. Additionally your towing ability will drop substantially due to the higher gears.
My 2002 Expedtion with the 5.4L never got better than 14MPG and that included highway miles, and it didn't weigh what the SD does.
So IMHO changing your gearing is just throwing away good money. If you really need better gas mileage then get a smaller liter truck in 2 wheel drive.
Just my .02
Last edited by blackhat620; Sep 28, 2006 at 03:05 AM.
Tuned
Joined: Jun 2005
Posts: 421
Likes: 1
Dont waste you'r money I went from 3.73 to 4.56 for oversize tires 37-13.50-18 I also had a 5.4
To help get back the bottem end and so it would stop shifting in and out of OD up on the hwy this did fit those problems but the MPG stayed the same 11 MPG save you'r money.
You want low gears with the 5.4 SD are heavy Trucks.
To help get back the bottem end and so it would stop shifting in and out of OD up on the hwy this did fit those problems but the MPG stayed the same 11 MPG save you'r money.
You want low gears with the 5.4 SD are heavy Trucks.
Senior User
Joined: Jul 2006
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I have 3.73's on my 2006 F250 5.4L and get about 12 mpg of mixed driving. If anything, go to 4.56's since you tow a trailer. That is what I am going to do so it will tow my travel trailer better.
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With the 5.4L engine and cc and 4x4 I would stay with the 4.10 my old F350 a 2002 sc 4x4 with that engine would get 10-12 in the city and 14-16 on the highway and towing I would get 12-15 depending on weight and how fast I drove. I would never put a higher ratio lower numeric gear in the gas engine. I never had any trouble getting mine to put from the start or when I was off road. Ford has the right idea with the 4.10's and the 5.4L engine.
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Posting Guru
Joined: Jan 2003
Posts: 1,238
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From: Back in the TX Coast
Pappy,
Stick with 4:10's
I have a 2002 4x4 crewcab 5.4l longbed with 3:73's with 60k miles and on my best day I ONCE got 14.91
The other 4yrs i have had this truck i avg 13 mpg city or highway hand calculated. So don't waste your money not to mention you will lose some of power
As for the other stuff same deal save your money for gas as the results of this mpg gadgets are minimal at best
Stick with 4:10's
I have a 2002 4x4 crewcab 5.4l longbed with 3:73's with 60k miles and on my best day I ONCE got 14.91
The other 4yrs i have had this truck i avg 13 mpg city or highway hand calculated. So don't waste your money not to mention you will lose some of power
As for the other stuff same deal save your money for gas as the results of this mpg gadgets are minimal at best
Posting Guru
Joined: Jul 2006
Posts: 1,191
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From: New York
I agree with the others regarding the gearing. I just had mine changed from the 3.73's to 4.30's mainly for lower end pick-up. I saw a slight affect in mpg's, but the performance outweighs the fuel economy by a wide margin. I would NEVER consider switching back (nevermind the cost to do it) just to try and save on the gas. The truck is too heavy and the weight it is designed to pull warrants the 4:30 gearing more so than the 3.73's. Of course, it is your decision, and if you are dead set on changing them back, I still have my 3.73 gears in a box - I can save you a bundle if you want 
Cargo Master
Joined: Nov 2004
Posts: 2,751
Likes: 3
From: So Oregon
I would figure out how much 1 - 2 mpg increase will gain you and see if $1500 (approx cost of r/p change) can be better spent somewhere other than automotive pursuits. At $3.00/gal and 10mpg it's what $0.30 a mile? If you get 12mpg it is $0.25 a mile??? So you save $0.05 a mile and it would take 30,000 miles to re-coup your cost of the r/p? If gas is more or less, well you get the picture. Also, I don't know if 2mpg difference would be the norm or not since it takes less work for the truck to pull it's own weight with lower (numerically higher) gears.
I'm not real sure my math is right, so you probably would want to do your own. I think the perfectly tuned comment is more right on. A clean air filter, regular maintanence and I think that's probably the best money spent for mileage.
I'm not real sure my math is right, so you probably would want to do your own. I think the perfectly tuned comment is more right on. A clean air filter, regular maintanence and I think that's probably the best money spent for mileage.
