What's your preference and reasoning F-350 3.55 or 4.1

[hogan]

A friend asked me what my take was on gearing for F-350. I admit I don't know much about that so I thought I would consult the experts.

What's your preference and what is reasoning? MPG, towing power, etc.

 

[fastcarsspeed]

Do they not have a 3.73 option? 4.10 gears are great for low end but is going to hurt to fuel mileage. I would think you should be ok with the 3.55. What weight are you looking to pull and also where? Weight and elevation/hills will make a difference. I have a 350 with 3.31 gears and wish i had the 3.55 gears at the very least but I pull just fine.

 

[LBR]

Two members here left a rally with comparable 5th wheels a couple weeks ago....one with a F350 3.55 gears, one with F450 4.30 gears...2 complete different chassis with same 6.7L PS... and convoyed a few hours, then compared fuel mileages....both were exactly the same...I believe it was 8.7 mpg.

If I missed or got something wrong am sure I'll get corrected, but one of them will check this and verify how far they drove and if mpg was different than I stated.

 

[Jesstruckn/Jesstalkn]

I'll correct that a bit.
I have the 2017 F-350 w/ 3:55's and Rod has the 2017 F-450 with 4:30's we both reset and drove about 130 miles bumper to bumper the hole way 65 on the freeway and Hammer down going through the hills up to Bass Lake. We were both bouncing around 11.4 on the freeway then when we hit the hills they both dropped down. "And we were rolling" these trucks are UNBELIEVABLE !!!!!!
End result was both truck at 8.4 at the end of the trip.
He said he didn't really have much more pulling power climbing the hills. I know he had to have a little more but not much. We are both right at 30000 lbs.
His truck is pulling most of the time, and mine is 50/50 I love driving my F350 as a daily driver. And I roll 75 to 80 mph most of the time.
So if I was pulling over 30000lbs all the time I might go with the 410's but. My 3:55's are amazing with the 30000lbs weight I'm at now. I'm climbing the Siskiyou and the Tehachapi mountains at 60 to 65 mph no problem .. it's crazy how much power these new trucks have.

Note at 80 mph im at 2000 rpm
I'd do the 3:55 again but would like to try out the 4:10's some day.
I think 3:73's would be a good medium but they must know more then I do

Hope this helps

Jerrod

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[LBR]

Thanx so much!...this is real boots on the ground testimony right here!!

 

[MCTalley]

In its basic form, the rear gear ratio is a torque multiplier. If you multiply the rated engine torque by the rear end ratio, you can find out the theoretical torque to the rear wheels at a 1:1 transmission ratio, which the Ford 6-speed auto doesn't have, but let's pretend it does. Also, not all of these gear ratios are available each year, but each have been available in different models over the years.

Year/Engine      HP     TQ     4.30    4.10    3.73    3.55    3.35
-------------    ---    ---    ----    ----    ----    ----    ----
1999-2000 7.3    235    500    2150    2050    1865    1775    1675
2001-2003 7.3    250    525    2258    2153    1958    1864    1759
2003-2004 6.0    325    560    2408    2296    2089    1988    1876
2005-2007 6.0    325    570    2451    2337    2126    2024    1910
2008-2010 6.4    350    650    2795    2665    2425    2308    2178
2011-2014 6.7    400    800    3440    3280    2984    2840    2680
2015-2016 6.7    440    860    3698    3526    3208    3053    2881
2017-2018 6.7    440    925    3978    3793    3450    3284    3099

Note that for the 2017-2018 trucks using a 3.55 ratio, you have 3284 ft.lbs. torque at the rear wheels. Compare to the 2015-2016 running a 3.73 at 3208. So even with a 3.55 ratio in the new trucks, the higher torque rating still pulls better than the 3.73's in the previous models.

Comparing numbers between different years, we've come a long way for sure. For example, we started with a 2002, moved to a 2013, then our current 2016. All three had 3.73 rear ratios, giving 1958, 2984 and 3208 rear wheel torque, respectively. Them's some big numbers.

 

[boatto5er]

This is a subjective observation. We just finished a long trip thru S.Dakotah, Montana, Wyoming, Colorado, and several fairly flat states pulling our 16,000 lb Landmark. Our 2017 F350 Dually with 3.55s was incredible. To use an overused phrase, “It was like there was no trailer back there”. No science or math, just extreme satisfaction with this truck’s performance. By the way, objective numbers. average fuel economy while towing: 10.2, not towing 14.7

This includes hills/mountains, flat terrain, stop and go cities, hiways.


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[hogan]

This is a subjective observation. We just finished a long trip thru S.Dakotah, Montana, Wyoming, Colorado, and several fairly flat states pulling our 16,000 lb Landmark. Our 2017 F350 Dually with 3.55s was incredible. To use an overused phrase, “It was like there was no trailer back there”. No science or math, just extreme satisfaction with this truck’s performance. By the way, objective numbers. average fuel economy while towing: 10.2, not towing 14.7

This includes hills/mountains, flat terrain, stop and go cities, hiways.


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Thanks to all of you who have responded thus far. I have forwarded a link to my friend and he appreciates your offerings. I do too. Hogan

 

[Jesstruckn/Jesstalkn]

So with all of that info what would you pick ??

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[3760EL]

We have a 2011 F350 SRW 355 gears 400Hp 800 Ft.Lbs torque towing a 16,000 lb Big Horn 5er. Towed East to the Dakota's, Montana, Idaho,Wyoming, Neveda, north to Washing south to L.A. Ca. Have to agree that this combo is a pulling dream. It pulls grades of 6% with ease. Mileage towing varies from worst 8.7 to best to14.7 at 58 mph. Empty at 70mph hi of 22mpg. Highly recommend this combo.

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[travlingman]

I have a F-350 dually with the 4.10 rear end. Camper weights in a little less that 16K. Just got back from a 760 mile trip to the beach. Traveled over the mountains from Tenn into NC by way of I-26 over Sams Gap thorough Asheville. For the trip averaged 9.6 MPG. Truck ate the mountains up. Coming back, going up the Saluda grade, I was at 65 MPH when a slower car got inf front of me and I had to get out of the pedal. Dropped down to 60 MPH and the car got out of the way. Got back into the pedal, never dropped out of 5th gear and held 60 MPH to the top at 2200 RPM. This thing loves to climb around 2500 RPM's.

The advantage to the 4.10's over the 3.55's IMO, is that you have better bottom end, think acceleration onto interstate. If you have to get out of it on a mountain I think the 4.10's allow you to be able to pick your speed back up easier.

With that said, the 4.10's are overkill for the weight I am pulling. 3.55's would easily do the job. But, I am glad I got the 4.10's.

 

[LBR]

I prefer the lower gear ratios that are matched properly to the chassis, engine, usage and such. Our pickup TV now has 4.88s and does a great job pulling our 20K CY, but we sadly feel the need to update to a newer pickup.

 

[shurack24]

Just another opinion here; but the 6.7 has so much torque that it can spin the 3.55 with ease. If you are approaching weight limits, or regular giant mountain climbs the 3.55 is super. Our 2011 SRW pulls our 14k lb 5er with ease. Have not hit a hill yet that slowed it down.

 

[Alan_B]

So far I have been happy with the 3.31 gearing on our F-350.

We are part-timers and take 3-4 trips a year. When I figured out the small percentage of the time I would actually be towing, and added in 925 lb. ft. of torque from the diesel engine, I went with the shorter gearing.

Sure there will be times that I will wish for taller gearing. But overall I am happy with the pulling power and the fuel economy.

 

[CDN]

Second Super Duty with 3.55 gears. I have no problems with torque on our 16,000 lb BigHorn. We don't have mountains in Ontario but some 2 lane secondary highways have steep grades and lots of turns, getting back up to speed is not problem and engine braking saves linings too. Both trucks are snow plow package along with stiffer front springs. With FX4 hill descent is great for steep campground maneuvering keeping speed down on gravel.

 

[Mark-Roberta 051995]

Well, my Dodge Ram 3500 - oh heck - just playing here.

Happy Friday everyone and this was a great read as I am looking at a new truck for next year. Good information.