My delema,
My 2008 F250 5.4L supercab is maxed out trying to pull a 9k pound 5th wheel. The truck has a 5.4L triton with a 3.73L rear end and the 5 speed auto. Normal day to day is 15 MPG. On flat ground I can get into 5th gear and over drive (10MPG) pulling the 5th wheel. If there is any hill or head wind the truck locks into 4th gear (7.5 to 8.5 MPG). The worst we have done is 35 MH in 2nd gear up the grapevine on I-5 in CA (NO MPG). It looks like I need to gear down to increase my pulling power. I know the factory says that the 4.11 can haul up to 12.5k pound trailer. and over 14k (with a diesle and the 4.30 rear end). Any thoughts on which I should choose a 4.11 or a 4.30 ring and pinion set to improve pulling power. The trailer is pulled 3 to 5 times a year some times up to 2k miles one way.

 

4:30 for sure with the 99 - 2000 5.4's...I don't know in your case...I wouldn't do 4:11..

 

Should have come with 4.30s stock. No gasser, especially a modular, should come with a ratio starting with 3 point anything. Heck even my '02 Ranger had 4.10s.

 

I think you will be much happier with the 4.30 gears instead of trying to make a small difference with the 4.10 gearing. I don't even think your day to day mileage will change that much because the motor will be able to stay in its power band better even when you are unloaded.

 

Another vote for 4.30's the 4.10's aren't enough of a change to spend the money to do it 4.30 also seems to be the sweet spot for the mod motors with stock size tires.

 

My 2010 Superduty came with 3.73 ratio stock. Very common stock gear for these trucks.

 

You're missing the point; just because it does (which obviously it does, or else we wouldn't have an incessant parade though the forum of 5.4 and 6.8 owners lambasting the 3.73 gearing in their trucks and asking about costs to swap) doesn't mean it should. There's a reason why in 2008 Ford rated the GCWR of a 5.4 w/ 3.73s a solid 5000# lower than any other gearing/engine combo, because that setup can't handle any more weight without driving experience deteriorating rapidly. OP is pulling 9k in a truck that weights at least 8k, meaning he's minimum 1000# over what Ford could justify arguing the combination could handle comfortably. That's the point of GCWR, it's not a legal or even a real rating, it's a common sense "hey, the truck might struggle after this point, so don't complain to use b/c we told you it wouldn't be fun."

More gear is rarely a bad thing if you're pulling. My 6.0 should have come with 4.10s, especially in the SRW F-350 with the higher load capacity upping what they can pull for pin weight without needing to up to a dually yet. But if you're only towing groceries, it won't matter all.

 

Thanks, I understand now. I misunderstood what you were saying. I thought you meant that these trucks never came with that gear.

 

Thank you every one for the advice it helps with my decision. Looks like 4.30 it is and the heck with the MPG. Since my commute is less then 15 miles one way I am burning about 2 gallons a day anyhow. I know this engine can do better if I can get it into the power band. I guess a cold air kit and 4.30 gearing then see how it pulls. Worst case I can add cat back and chip it for more power. Would love the Diesel but that is not in the cards for a few years.
It is hard to hate a truck that is so simple it does not even have a chip in the key.

 

I could not agree more. Since there are no MPG guidelines on these trucks, why such a high gear on a SUPER DUTY work truck??? 4.10's at least!
Mine has 3.73 and I hate it. Going to 4.30 soon.

 

Rino coated bumper

As you can see there is extra weight on the truck to haul around. Two Rhino coated bumpers. Tool box, cab protector, and steps.

 

Don't be too surprised if after the swap your unloaded MPGs stay about the same and I would expect to see your towing MPGs go up, mine did.
We were seeing towing MPGs of 6.5 to 7.5 with the stock 3.73 gears (and stock 31.5" tires), swapped up to 4.88 (with 35" for an effective ratio of 4.39) and now see regular towing MPGs of 8.5 to 9 with a best so far of 9.25 MPG. This is on our V-10 EXcursion pulling an 11k TT.
I will also strongly recommend some custom tunes from 5Star, the transmission performance increase alone is worth it and any small power increases are just the gravy on top!

 

I have the same truck in fwd. I have 4.10s factory. It pulls my 7200 lb bumper pull fine but I think 4.30s would be better. By the way driving nice, not pulling my trailer I get 14 hwy.

 

Don't fear the gear. I bet your around town mileage goes up with a steeper gear

 

I am hoping with changing to the 4.30 my truck will stay in 5th gear instead of dropping into 4th. A lot of my trip from CA to TX was in 4th gear because of headwinds and or hills (even small ones). Any one using gear set other then Factory? Looking at Sierra gear set over OEM do to price.