rpm @ 65 & 70 mph

[Cyncwby]

This question is for the Ford guys with the F-350/450 and a 4.30 rear end ratio. What are your rpms at 65 and 75 mph. After 14 yrs. I'm going to sell my "02 F-250 PSD and get a F-350 Dually crew cab PSD. Just wondering what kind of rpm's you're turning while towing and solo....thanks

[notanlines]

Cowboy, two things to keep in mind. Your RPM's will be the same, whether you're towing or not. 6th gear is 6th gear no matter the load. 4:30 gears are seriously low. You need to be hauling a triple axle beast or heavy equipment up and down big hills to call for those gears.

[larry337]

Couple more things. The 4.30 is standard on the f450 and only available on the F350 with a heavy haul package that includes a wider front axle. I suppose if you don't care about fuel mileage the wider axle does improve steering ratio. But the 3.73 is all most people need. The 6.7 and 6 speed transmission are barely even working with most RV trailers. You gotta be north of 20k to want a 4.30. To try and answer you're question if I'm 65-68 MPH I'm at around 1800 with a 3.73 and get 11 mpg towing.

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[jsmith948]

Originally Posted by Cyncwby

This question is for the Ford guys with the F-350/450 and a 4.30 rear end ratio. What are your rpms at 65 and 75 mph. After 14 yrs. I'm going to sell my "02 F-250 PSD and get a F-350 Dually crew cab PSD. Just wondering what kind of rpm's you're turning while towing and solo....thanks

With the newer high torque rise engines, you do not need to be so low geared.
Our super duty has 3.31s. I wouldn't consider going lower than 3.55 unless I was going to tow something REALLY heavy. JMO

[Cyncwby]

Ok good info, keeps me from making a BIG mistake. My '02 7.3 is a great engine and has been trouble free for it's 138k miles so far ........ but it's rated at 250 hp and 505 torque. I did install a BD "tow" chip right after I bought it, they claimed 60 hp and 110 torque and that made a very big difference in how it ran. Boost and pyro gauges keep me aware of how happy it's running. With the new 2015 HP rating of 440 hp and 860 torque I can see how the 3.73's will be quite adequate. Thanks again for the info........Dave

p.s. in regards to what jsmith said ..... we have a 2013 Montana Mountaineer 295RK that shows a dry weight of 10,120 and max trailer weight of 14,140. We usually tow VERY light (no water or gen.) so I doubt we have ever reached 12,000 lbs. I also installed a set of Sailun 637's right after we brought it home which really make it tow nice. So that being said, do you think a 2015 F-350 dually crew cab with a 3.55 ratio would work ok for this rig on the flats and some mountain pulling........ and YES, I do care about the mileage.

[JRTJH]

We've got a 2015 F250 CC 4x4 short bed 6.7L with 3.31 gearing. We tow an XLite 27RKS that's about 9,000 to 9,500 lbs ready to roll. Towing in the mountains on steep grades, I find that I need to downshift to 5th to stay in the "power band" (1700-1900 RPM) at 60-65 MPH. The 3.73 gearing would be in that RPM range in 6th gear.

We had more than enough power (in 5th gear) pulling 8 percent grades at 65MPH this summer and often pulled 5 and 6 percent grades in 6th gear. I wouldn't want anything but 3.31 or in your situation 3.73 gearing. I think you'd find that the 4.30 gearing would put you wishing for a 7th gear to lower your RPM when not towing with no "real benefit" when you are towing.

ADDED: The 2015 F350 DRW 4x4 is not available with 3.31 or 3.55 gearing. The only choice that I know of is either 3.73 (standard build) or 4.30 (HD towing build). It would be "nice" with the dually to be able to get the wider stance front axle option without the 4.30 gearing, but to my knowledge, that is not available, even with a special order.

[Cyncwby]

Yes sir you are correct on the options, I just spent a couple of hours going over all the "neat" things that I would like to have. As you say the 3.31/3.55 are not available so the 3.73 will have to do.

I did some calc's, the diff. between the 3.55 and 3.73's @ 65 mph is only 83 rpm and @ 75 it's only 95 rpm. Hardly anything to get worked up over.

Yes I did see the wide track front axle and larger flares, looks great and the shorter turning radius would be nice but again, only available with the 4.30 gears. They must pull these right off of the F-450 line but they don't come with the 450's larger brakes. Anywho, thanks again

[Brantlaker]

I just picked up a 2016 F350 DWD 6.7 with a 3.73 rear and I traded in a2015 F350 SRW with a 3.55 rear the difference in milage is about 1-2 MPG and RPM Is really hard to tell. my old 5er loaded was 11255 lb and my new one is 17555 lb and I can tow up to 23500 lb as per Ford on my door sticker. If you are ordering a new on order it with the slide in camper package #471 it gives you 500 lb more pin weight with a higher spring rate and larger rear stabilizer bar.

[larry337]

I can verify the FX4 package does not include a 4.30 rear, maybe in some other configuration, possibly a gasser, but not in a diesel dually.

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[old timer]

I would recommend a air bag setup on any heavy duty truck. I have a 250 and it was harsh to ride in over ruff roads. As soon as I installed the bags I had a noticeable improvement over the stock setup. It connects the axle to the frame and cushions the ride. I run 10 to 12 lbs empty and 60 to 67 loaded.
As for gears I have the 3.31's and I'm impressed at how well the truck handles a load. It accelerates better than I expected with those gears.
I get about 18 empty on the highway and have seen 20. However loaded I got 12.2 pulling my 20 Montana 3280RL.

[T11ravis]

Originally Posted by old timer

I would recommend a air bag setup on any heavy duty truck. I have a 250 and it was harsh to ride in over ruff roads. As soon as I installed the bags I had a noticeable improvement over the stock setup.

Are you talking about towing or empty? I love my bags when towing but they definitely stiffen my truck up too much when empty even with min. psi.

[gearhead]

Originally Posted by larry337

I can verify the FX4 package does not include a 4.30 rear, maybe in some other configuration, possibly a gasser, but not in a diesel dually.

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The last time I tried to configure a diesel F350 DW on the Ford website, and selected the 3.73 gears with FX4, the site wouldn't let me. Whenever I selected FX4 it would select 4.30 gears. I decided if I wanted a 4x4 it would not be a FX4.
Maybe it has changed?

[gearhead]

Originally Posted by larry337

I can verify the FX4 package does not include a 4.30 rear, maybe in some other configuration, possibly a gasser, but not in a diesel dually.

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I went to the Ford website and you are right. Either they changed it for 2016, or I am confused as usual. I was building a 2015. I remember getting a bit frustrated with Ford. I wanted the FX4, but not the 4.30 gears.

[larry337]

Originally Posted by gearhead

I went to the Ford website and you are right. Either they changed it for 2016, or I am confused as usual. I was building a 2015. I remember getting a bit frustrated with Ford. I wanted the FX4, but not the 4.30 gears.

I know in the past that site can be confusing. I havent tried to build a 2016. 3.73 has been the only rear end offered in a dually for quite some time and is really all that is needed. FX4 has always been available. Dually 3.73 with FX4 is what I have. To get the 4.30 you have to select the high capacity tow package which also includes the wide front axle like the f450. Standard f350 dually with 3.73 tows like 23,000 and high capacity bumps it to 27000 I think, I can't keep track of it. F450 includes 19.5 inch wheels which look badass, wide front axle, and the 4.30 and tows something like 30k plus. I love the look of the F450 but my standard f350 dually is already more than I really need.