I'm in the market for a new F-550 with the 6.7 diesel that will be used for pulling a gooseneck freight trailer. I run about 400 to 500 miles a day, mostly highway, mostly loaded 25k to 30k total, so gearing the truck to run at the optimum cruising RPM is crucial for my application. I haven't been able to find anything on any of Ford's commercial truck sites as far as a recommendation. I also haven't been able to find the governed or max rpm for the new engine. I will not listen to any salesman because they don't give a flip, or have any clue as to what is good bad or ugly. They just want to roll a truck over the curb.
I am looking for some advice or facts on how to gear the truck. The F-550 is available with 4.10, 4.30 or 4.88 gears. The difference in RPM's at 70 mph as best I can calculate it out are this: 4.10 @ 70 mph - 2080 rpm, 4.30 @ 70 mph - 2180 rpm, 4.88 @ 70 mph - 2475 rpm. These numbers are all in 6th gear at 70 mph.
If any of you out here run a F-450 or F-550 please chime in about how your truck is geared and how the fuel mileage is, and if you think it's too high or too low for your application. I know the mileage number will be relative as it depends fully on loaded weight and aerodynamic factors (tall freight hurts!) but just so I can get a general idea. I have a V-10 now and anything better than 6.5 mpg will be a win!!

 

I have a 2011 F-450 pickup. I'm towing a 21,000 lb fifth wheel (High profile 13'3" height). I get 9.5 to 10 at 62 mph with 4.30 gears. The truck runs very comfortably around 1800 rpm at 62 mph with no shifting or hunting in the transmission. I'm happy with the setup and wouldn't change anything.

One big difference between my F-450 pickup and the F-550 Cab 'n Chassis is that the Cab 'n Chassis has the power and torque severely derated from the 400/800 numbers. Not sure if that will make a difference in mileage, but it certainly will affect towing performance, especially in the mountains. I got rid of my 2006 F-350 (325/575) because it would downshift with this trailer everytime I went over a freeway overpass and 65 mph was about it. I also picked up almost 1 mpg with the new truck.

 

Can you get the 3.73 or do you want the 4.10? I would suggest the 4.10 if you can't go lower. (higher)

 

@ruschejj:
The ratios available in the F-550 are 4.10, 4.30, and the 4.88's. However as I read thru the ordering guide I find that with a certain option I want/require for my specfic application (high capacity payload, which includes an axle upgrade to a Dana S130) is only available with the 4.88's.

@glsurratt:
Yes, the C/C trucks have ratings of 300HP/660TQ. I'm sure they don't pull quite like a 400HP/800TQ truck, as they are detuned a bit to increase the life of the engine.

I'm really looking for feedback on how this new engine would handle 2400+ rpm's all day long. And do any of you F450/F550 owners out there have any reliable numbers on mpg?

 

Try sending this guy a PM:

Ford Truck Enthusiasts Forums - View Profile: cabindoc

Scott's got a 2011 or 2012 F-450 CC with a Flatbed dump body he uses regularly. He should be able to give you some pretty good insight.

Here's the thread from when he got the truck:

https://www.ford-trucks.com/forums/1...d-chassis.html

 

I run a f350 cab chassis with 4.10's and tow a gooseneck horse trailer that is extra tall for draft horses"aka areodynamics of a brick" wheight of horses and steel trailer and a bit of odds and sods are #16,000 pounds. TRUCK RUNS LIKE A CHAMP tows great and fuel runs 10.5 mpg running 65 to 70 mph. not sure what the truck weighs to add to the total number

 

@glsurratt: I just ran across an article that says the HP ratings are achieved in different ways (engine dyno vs. chassis dyno) for trucks over and under 14,000# GVWR. So even with the single stage turbocharger, the C/C trucks are still making decent power, despite the different testing methods.
Most chassis dyno numbers are about 20 to 25 percent less than engine dyno numbers.

 

That may be. But if it is, Ford is going about it wrong from an advertising veiwpoint. GM is saying the cab 'n chassis will have the same output as their pickups. Ford is advertising significantly lower numbers for the cab 'n chassis.

And the F-350 is less than 15,000 in either configuration and the numbers don't match up, assuming they used the engine dyno method for both.

Look around and you'll find they are having problems with the derated cab 'n chassis 6.7 sucking valves too. So much for "longer engine life".

 

I have the 4.30 gears in mine. It will pull damn near anything I'm sure. 4.88's are overkill for this engine. You want lower rpms as power drops off quickly the higher you rev it. The transmission gearing more then makes up for it. I got all the high capacity options. Depending on how you do it you can get the 4.30's. I highly recommend them! Towing my telehandler (27000 lbs dry) with trailer it is almost 35k for short trips I get 22 liters / 100 km (sorry I don't have mpgs for you).

With this gear it actually gets better fuel economy in the city then the highway. So go for the lowest rpm gear that will accommodate your load.

 

Thanks for the input. I visited with my local dealer dude today and he tells me (and showed me) if I order the F-550 with the High Capacity Trailer Towing option ONLY, I can still get the Dana s135 with 4.30 cogs. The Payload Upgrade Package will give more spring, a 14,706 axle capacity (vs. 13,660), and double frame, but only comes with 4.88 cogs. So we will leave that one on the table.
I will be using this truck as a hotshot 'tractor' pulling a lightweight stepdeck trailer, sometimes I would be loading to full capacity, about 35k to 40k total weight.
https://www.facebook.com/media/set/?...type=3&theater
Salesman says the 4.88's are good if the truck will only see limited highway use, but for my use the 4.30's should be just about perfect.
Now I just gotta get the bank prez convinced.