Ford F350 axel ratio 3.31

whitebb wrote:
I have a F-350 6.7 4/2 with a 3.73 and pull a 5th 39 + inches or just say 40 feet, weight 16,500 with no problems and get average towing of 12-13 mpg in low hills you know overpasses and such. Have got in 15-16 on level road of 20 miles are so. Works fine for me. Running on hwy empty normally get 19-23 regularly. Just my two cents worth.:)

Even more unbelievable.

'12 F350 SB, CC, SRW, 6.7 PSD, 3.55 RAR, 6 spd auto, Ultimate Lariat pkg
2011 Open Range 393RLS 14,250 GVWR
Pullrite Super Glide 18K

keyspirate wrote:
I am towing 15K and getting 15 mpg at highway speeds. 2012 srw.

Unbelievable. I mean...really...unbelievable.

I get 16 MPG empty. And 11.0 to 11.5 towing 14,000 on flat Florida roads with no winds. At 62 MPH.

I pulled 14,000 lb 5vr (CAT scale weights), and 8100 lb. truck weight (total 22,100) last summer around 6000 trailer miles with the 2012 F350 SRW 3.31 4x4... Pulled fine and handled well. We were at max listed payload weights.

I didn't have a choice as to what gears I wanted! It's a Non 4x4 , so the only option I was given was 3:31. My FW may weigh loaded without full water, maybe total water 15 gallons (12k). Maybe I am in over my head! My 99 V 10 has NO problems what so ever!
Only time will tell. 11 mpg sounds good! I get 6-7 max running about 67-70!

Bruce.

I have a 2011 F-350 SWR 4x4 w/6.7 and on our first trip empty we went 325 Interstate miles @ about 65mph and dash read 20 mpg. On return trip of about 400 miles, mostly on state highways towing a 38foot fiver the dash read 11 mpg., speed ranged from 55-65 mph. The truck only has 8000 mi. on it. I'm told not to expect the best mileage until we get around 40-50,000 miles on the engine. We're running 3.73 gears.

my 2011 has the 3.31, and I've had no issues while towing, even pulling the hills her in Az.

I have a F-350 6.7 4/2 with a 3.73 and pull a 5th 39 + inches or just say 40 feet, weight 16,500 with no problems and get average towing of 12-13 mpg in low hills you know overpasses and such. Have got in 15-16 on level road of 20 miles are so. Works fine for me. Running on hwy empty normally get 19-23 regularly. Just my two cents worth.:)

The 5R110 behind the 6.4 and the new 6R140 behind the 6.7 are apples vs oranges. Completely different transmission and gear ratios plus the 6R140, unlike the 5R110, has no direct 1;1 drive gear.

The 3.31 rear gears works fine with the 6R140 tranny with its lower ratio 1st gear. The 3.31 with this tranny has gear splits similar to the older tranny with a 1;1 and a 3.7x to 3.9x depending on tranny gear selection.
The 3.55 has similar gear splits as a 4.1 to 4.3 depending on tranny gear selection.

No I'm not a Ford guy however I do understand why a 3.73/4.10 isn't needed with the new 6R140 tranny with its lower gear ratio splits for towing 15900 lbs.

And yes the Allison or the Rams Aisin and 68RE trannys still have a 1;1 drive gear with two OD gears so yes they use a 3.73 or a 4.10 axle ratio depending on truck size selection and tow ratings.

If you have problems getting sufficient torque, you might add an outboard two speed "axle" It is just another gearbox that goes behind the transmission and gives you the capability of using a higher ratio drive when you need.
Russ

Vangoes
Wow, I didn't really have a choice! Only way to move up to 3:55 or higher would be to get a 4x4 which I didn't want! Guess I will find out the hard way and will either be satisfied or not satisfied. Only time will tell! Thanks for your input!

Bruce.