Hi all -
I've decided to go with a 6+3 lift and not sure which gear ratio to use. I hear some using 4.56 and others 4.88. Here is some additional info:

Year: 2003 F150 SuperCrew Fx4 (3.73s)
Engine: 5.4
Planned Lift: 6+3
Planned Tires: 38's
Planned Wheels : 18" or 20"
Driving: It's my daily driver, 90% highway, little off-road if any, mountains in the winter for snowboarding, little to no towing now (but may start towing small open trailer with MX bikes...nothing big)

Some questions:
1) Which gear ratio would suit me better? Why?
2) Does one gear ratio allow for better mpg?

Thanks!

 

i would definately go with the 4.88s. 4.56s are better suited for 35's. specially with the modular motors ford stuck in these trucks. theyre nice but lets face it they aint really got that much "truck" in them. shoulda offered the f-150 with 6.0

 

I have 4.56s, and I love the setup. It basically brought my drivetrain back to normal. I would suggest going with the 4.56s cause they give ya good gas mileage (as good as a monster like this can get) 12.5 city - 15 highway. And those gears will allow you go ANY speed you want. I personally have had mine up to atleast 100+ mph. I have heard that 4.88s may limit your speed, and those are the ones to choose if you are pulling a trailer. But if you are towing only that size trailer, I wouldn't worry about going with the bigger gears. When I rum 60 mph, my rpms are around 1600 which was where they were before I got the 38"s on mine. So, in short, go with the 4.56s front and rear.

whackemnstackem, he said he was planning on running 38s. No offense, but read his thread closer before posting.

"Year: 2003 F150 SuperCrew Fx4 (3.73s)
Engine: 5.4
Planned Lift: 6+3
Planned Tires: 38's
Planned Wheels : 18" or 20"
Driving: It's my daily driver, 90% highway, little off-road if any, mountains in the winter for snowboarding, little to no towing now (but may start towing small open trailer with MX bikes...nothing big)"

 

I would go with the 4.56's if it is your daily driver. I've heard that highway speeds are not practical with the 4.88's.

 

if you really plan on running 38's then 4.88's hands down. The gas mileage difference between 38's+4.56's and 38's+4.88's is a mute point. You will love the 38's come time to go up into the mountains.

I ran 37.5's with 5.38's for a small period of time and still had my truck on the interstate doing 85. 38's and 4.88's will be fine

 

Thanks all. Yes it's my daily driver and I'd like to keep the rpm's as low as possible (will 4.88s keep it under 2000rpm at say 60...compared to the 1600 @ 60 as mentioned above?). On the highway I avg about 80mph speed. I rarely hit 90 or above.


Lost Cause -
How do you like your BDS lift? I see most go with Fabtech. I just recently started looking at the BDS.

 

BDS is a great lift with an amazing warranty.

BUT just so you know the RPM difference between 4.56's and 4.88's is only a couple hundered RPMS... nothing worth going with a less gear.

Do whatever you want, but remeber the weak spot on these trucks drivetrains is the 4r70w

 

TRUE THAT! I just spent $3002.44 getting my tranny fixed! Slip ring, od band, torque converter, clutch, etc. destroyed! Pieces were everywhere inside. I have the Yukon 4.88's front and rear.. I love em. With your applications I think you will be fine with either. Just make sure your tranny is up to par!

 

I have heard that 4.88 would limit your highway speeds to around 75 - 80. Not sure on how true that really is.

 

NOT TRUE...

i ran 5.38's and 37.5's for a month or so. My truck would still do 85mph (via gps) your not gonna rev out with 4.88's and 38's

 

i was told something like that by some shops when i was looking around to get my gears done and it's simply not true. i've been at least 100mph in mine since i got 4.88's.

but to the OP i say you get the 4.56's. im good on the mpgs when i'm below 65 or so but if i get on the interstate and get up to around 80mph my mpg's drop bad.

 

Thanks for the input on BDS

Will the 4.88s put less strain (overall) on my drivetrain?

 

4.88's and 38's here

 

[QUOTE=rivydzl;4077864]TRUE THAT! I just spent $3002.44 getting my tranny fixed! Slip ring, od band, torque converter, clutch, etc. destroyed! Pieces were everywhere inside. I have the Yukon 4.88's front and rear.. I love em. With your applications I think you will be fine with either. Just make sure your tranny is up to par![/QUOTE

$3000? I spent 1300 to have everything re-done. racing clutch packs, kevlar gears, shift kit, and rebuilt the torque converter as well.

 

Not true, I'm running 4.88s and can hit 85 - 90 easily. I never need to go much faster than that though.