Gearing Question
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Junior User
Joined: Jun 2003
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Gearing Question
I just bought my first 4x4. I bought a 2003 F-150 Super Crew. 6" lift with 315x75x16 tires. The sticker said mileage should be 16 on the highway and Im getting around 10!!! I am running 3:73 gears in it now and want to know if I change them will it get better?
Right now: 70mph in overdrive is about 2000rpm. I dont think im hitting the trucks powerband yet. What would be the best gears to run with this setup - Im trying to get the dealer to replace my gears to bring up the mileage. I drive mostly highway and my boat is only about 3300 lbs.
Any info would be helpful?
Ed
Right now: 70mph in overdrive is about 2000rpm. I dont think im hitting the trucks powerband yet. What would be the best gears to run with this setup - Im trying to get the dealer to replace my gears to bring up the mileage. I drive mostly highway and my boat is only about 3300 lbs.
Any info would be helpful?
Ed
Senior User
Joined: Aug 2001
Posts: 380
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From: Illinois
Gearing Question
Sounds like a nice truck...
4.10s OR EVEN 4.56s would help with your gas milage, towing and overall performance since you are running that large a tire. If you get the dealer to change them for ya, try to get then to stick a limited slip in there too if you don't already have one.
4.10s OR EVEN 4.56s would help with your gas milage, towing and overall performance since you are running that large a tire. If you get the dealer to change them for ya, try to get then to stick a limited slip in there too if you don't already have one.
Post Fiend
Joined: Sep 2000
Posts: 8,238
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From: Oregon
Gearing Question
Originally posted by SplashMan
4.10s OR EVEN 4.56s would help with your gas milage, towing and overall performance
4.10s OR EVEN 4.56s would help with your gas milage, towing and overall performance
the above statement is true except for the mileage part. Those gears will cause your mileage to worsen. Only wanted to point that out since mileage seems to be his prime concern.
Senior User
Joined: Aug 2001
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From: Illinois
Gearing Question
I guess two out of three ain't bad, but when I regeared from 3.73s to 4.10s (running 33x12.5R15s) I got better gas milage and the RPMs dropped back down to near stock also. After regearing and running the bigger tires my power and everything basicaly went back to where it was with the stock tires and 3.73s.
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Junior User
Joined: Jun 2003
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Gearing Question
I havent towed with it yet... Im afraid to see what the mileage will be. If I would have know it would be this bad - I would not have bought it. My buddy has a 1972 F-250 4x4 with a 460 that gets just as good as my EFI 5.4. Its pretty bad.
Maybe somebody who really knows the answer can give me some information.
Lower rpm's dont always mean better gas mileage. You have to be within the power band of the motor, and I dont think mine is there now. I dont even know what the rpm's are stock since I bought it lifted.
Still looking for some good news about this.
Ed
Maybe somebody who really knows the answer can give me some information.
Lower rpm's dont always mean better gas mileage. You have to be within the power band of the motor, and I dont think mine is there now. I dont even know what the rpm's are stock since I bought it lifted.
Still looking for some good news about this.
Ed
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Post Fiend
Joined: Sep 2000
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From: Oregon
Gearing Question
Thats true, but typically that size of engine will get its best mpg between 2-2200 which is where your at now. When the bigger tires were put on was the speedo re-calibrated? If not, the odometer will also be off giving you a poorer mpg reading than its really getting.
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Junior User
Joined: Jun 2003
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Gearing Question
YEs - the dealer did calibrate for the tires. I just cant imagine that the mileage went down that far. The tires are only 34"-35" tall. That does not seem like alot to me. I downloaded some charts off the internet regarding rpm and gears and my truck does not match any of them...
Here is the link to a couple of the pages:
Four Wheeler Magazine
http://www.fourwheeler.com/techartic...TS/index3.html
SuperLitft
http://superlift.com/geartire.asp
Ed
Here is the link to a couple of the pages:
Four Wheeler Magazine
http://www.fourwheeler.com/techartic...TS/index3.html
SuperLitft
http://superlift.com/geartire.asp
Ed
Freshman User
Joined: Apr 2003
Posts: 35
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From: Central NY and Tug Hill Plateau
Gearing Question
If you go to the Super duty Forum of this web site, the second post should be Superduty FAQ's. There are some helpful calculators there.
Did that truck come "new" with a six inch lift? If it did, is it covered by factory warranty?
I have heard that you want a Dana 60 for a front axle if you want to run 35's for real off roading.
Your tires are 34.6" , It is my opinion that 3.73's are not suitable for that size tire.
How do you know you are 3.73, did you look on the sticker on the drivers door? My guess is that the lift is not factory, and maybe the person who did the lift possibly swapped the gears but did not change the info on the door jamb.
Did that truck come "new" with a six inch lift? If it did, is it covered by factory warranty?
I have heard that you want a Dana 60 for a front axle if you want to run 35's for real off roading.
Your tires are 34.6" , It is my opinion that 3.73's are not suitable for that size tire.
How do you know you are 3.73, did you look on the sticker on the drivers door? My guess is that the lift is not factory, and maybe the person who did the lift possibly swapped the gears but did not change the info on the door jamb.
Elder User
Joined: May 2002
Posts: 818
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From: northeastern ohio
Gearing Question
My friend has a ranger that gets 9mpg with 35" tires. A lift kit just makes a BIGGER brick to push through the air. I would say 10mpg sounds about normal, I would imagine your city mileage would be about the same also.
Rand
Rand
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