I was concerned about going with the 3:55 gear ratio on our F350. However towing something as light as the Augusta it has been fine and the mileage is better than any of our previous trucks with the lower gear ratios. All of the owners I have talked to that have similar trucks have said the same thing. Tow Haul and the double overdrive takes care of the grades and mountains just fine. I would only consider a lower ratio if I drove Mountains most of the time.
scottyb
Well-known member
So has anybody pulled a 18K rig in Colorado or similar mountain terrain with an F350 with 3.73's? If so, what gear do you have to be in on a long >6% grades? What kind of transmission temperatures do you experience. Does the fan clutch engage often to keep the engine temps down? What gear do you have to use to descend these grades and does the exhaust braking hold without having to apply the brakes? I am having a lot of turmoil deciding between a F350 and F450 for the gears. In 2013 the F350 has an available 14K GVWR to match the F450, but the F350 has a higher payload capacity at 6680 vs 5880, due to curb weight. Wondering where that 800 lbs comes from.
danemayer
Well-known member
We're pulling a 16K Landmark (actual weight is 15,000) with a 2011 GMC 3500 with 3.73. On the way up, I set the cruise control and let the truck decide on the gear. Going up is pretty easy. Downhill on 7% grades, I'll set the cruise control to 35, turn on the engine brake, and let the truck manage it all. I've gone up and down I-70 between Denver and Silverthorne a number of times without any concerns.
So do I have enough margin to do the same with an extra 3000 pounds? Don't know.
From the 2011 shootouts that I've seen, the GMC did better than the comparable Ford and Dodge on the run between Eisenhour Pass and Silverthorne; both up and down. But Ford may have closed the gap since 2011's came out. I think they were towing a pretty heavy trailer - might have been 18,000.
I saw a more recent shootout on 2013s (sorry, don't remember where) that noted with some concern the braking distance at freeway speeds on the Fords as being WAY longer than GMC or Dodge. That was without the trailer. Even worse when towing. If that's still the case, going down steep grades with 18K behind me would be concerning.
Bksvo
Well-known member
Yes, SRW 2008 F-350 CC/SB 4WD. 3800 is ~16.5 for me. Initially it was stock. It would pull comfortably at 35mph up a 6% grade, but the clutch fan would come on often. Down a 6% grade at 55-60mph, I would have to give the brakes a strong application every so often to keep the speed down, but not enough to heat things up.
I did mod the truck with a Spartan tuner and DPF delete. Running a 210hp tow tune, it tows like a dream. I have to conciously think about slowing down on grades. It would tow faster, but I try to keep it at 55 now up a 6% grade. The clutch fan rarely comes on. Oil temp will creep up to 240 (from ~215) and oil temp will go up to ~185 (from 165). Same performance from before downhill.
On my recent trip (Phoenix to Marysvale, CA and back) I get 8.5mpg average towing at 65mph.
dave10a
Well-known member
I have pulled my trailer over the Sierra's and Rockies and never thought the truck is underpowered with 3:55 rear end. Ford has done well with the design of this truck--- no complaints other than I am still finding new gadgets/features that Ford built in. Also I have averaged 12.5mpg and the fuel mileage over 10,000 miles of towing and the truck seems to improve with age. I had the same experience with the Caterpillar in my motor home. Seems like it takes 15 to 25K miles for diesel engines to break-in.
As I posted above we have towed some of the steepest roads and have no problems at all with the 6.7/3:55. If I were buying another tomorrow I would get the same thing. We had towed some of them with the 6.0/7.3 and this truck does it best even though the others had lower gear ratios.
