rpm @ 65 & 70 mph

Cyncwby · 10-12-2015, 06:40 PM

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 · 10-13-2015, 03:46 AM

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 · 10-13-2015, 04:46 AM

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 · 10-13-2015, 04:56 AM

Quote:

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 · 10-13-2015, 09:45 AM

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** · 10-13-2015, 10:19 AM

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 · 10-13-2015, 12:44 PM

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 · 10-13-2015, 06:46 PM

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.

Big Boy w/ Big Toys · 10-13-2015, 08:30 PM

I have a friend with the F450 and V-10.....7.7 mpg empty. Towing less then 10k maybe 6 mpg. If you are going to travel empty with it a lot and do not need the 450 stay away. The G rated 19.5 tires and the stiff suspension are awful. Wash board dirt road travel will rattle your fillings loose in a heartbeat. Speed bumps will rearrange your spine, especially if you miss the sign.

I tried to tell him but....well you know the rest of the story.

I have the '12 6.7l with 3.73 and wish I had the 3.55's. My heaviest tow combined is just a little under 25k. 11 to 13 mpg towing/load dependent. I can squeeze 18 mpg empty.

Cyncwby · 10-13-2015, 09:37 PM

Brantlaker and Big Boy.....thanks for the info, my 5th wheel is very light compared to your rigs. My F-250 handles the pin weight just fine so I don't think I'll need any extra. Just want the stability of a dually, 4 doors and what the hell, after 13 years I just want a new truck!

hankaye · 10-14-2015, 06:23 AM

Cyncwby, Howdy;

Like the others I don't have the model that you are looking for/at ...
That said, I do have a '04 F-250 (different engine), and it has a different
transmission, it does have the 3:73 rear and my tires are not the stock
from the factory size (slightly larger diameter and width).
My experience is that I sometimes get 18.something mpg while NOT towing.
Usually, 16.5 -17.5. While towing I get 10.5 - 11.5. That is from Grants, N.M.
to Green River, Ut. as an example.
I attempt to keep my rpm's at or slightly below 2,000 rpm, what some refer
to as the "Power band" area. That translates (for me), as roughly 68 to 73
mph. For me, ... 1500 rpm translates to roughly 55 mph.

Good luck with your new truck! Let us know how it works for you.

hankaye

Big Boy w/ Big Toys · 10-14-2015, 06:02 PM

Quote:

Originally Posted by Cyncwby

Brantlaker and Big Boy.....thanks for the info, my 5th wheel is very light compared to your rigs. My F-250 handles the pin weight just fine so I don't think I'll need any extra. Just want the stability of a dually, 4 doors and what the hell, after 13 years I just want a new truck!

The F350 and DRW will be night and day difference to your F250....I forget to say I running the F350 Crew Cab with DRW.

And before you ask if the truck is squatting in the picture the answer is yes.....We were in the middle of a 2 month trip with lots of "EXTRA" gear.

Cyncwby · 10-14-2015, 08:29 PM

Yea but it's not squatting very much, that's where a set of Air Lift bags would come in handy. Have them on my tuck and it really helps to level it out when need be. Is that the bronze fire color? Looks very nice with the 2 tone.

Here's my old horse, still running like a champ though

Big Boy w/ Big Toys · 10-15-2015, 05:37 PM

Quote:

Originally Posted by Cyncwby

Yea but it's not squatting very much, that's where a set of Air Lift bags would come in handy. Have them on my tuck and it really helps to level it out when need be. Is that the bronze fire color? Looks very nice with the 2 tone.

Here's my old horse, still running like a champ though

I don't remember but it was the Red of 2012 over the beige. The only thing against two tone is if any type of paint work needs to get done it gets expensive.

I still have my 7.3. 285,000 miles and still running strong. Looking to do injector o rings (2nd time) here soon. Other then an alternator, a water pump and one set of glow plugs it has been an absolute rock in the 15 1/2 years of running. Dumped my '05 6.0 which was a replacement for my '03 6.0 that never seen 10,000 miles before it was lemon lawed. There was never any real improvement with the '05. Head gaskets once a year.

C130 · 10-16-2015, 02:04 PM

My 2015 F450 turns 2000 RPM's at 65 mph and around 2200-2300 RPM's at 70 mph. Weird part to me is it'll be in 6th gear doing 35 mph through my neighborhood. The 4.3 is great for towing but as already stated it would be nice to have a 7th gear when not towing. Saying that, I'd get an F450 again for the brakes, wheels, etc. I love the way it looks.

I just recently switched toy haulers and while I think the triple axle tows better and smoother I can tell it weighs more as it'll downshift more often to 5th. When I had the 35 foot Fuzion it would hardly ever downshift and only did it on some decent up slopes or hills. I was amazed how few times it downshifted on our trip to East Tennessee back in June.

Cyncwby · 10-16-2015, 04:56 PM

C130.....thanks for the info, I'm assuming you were in the Air Force and was a pilot or crew chief. I love the C-130, man what a plane .... and they are pretty sweet with a 105, 40 mm and gatling guns a' blazin.

Anywho, yep the F-450 would be my choice cuzz it does look nasty alright. The only thing holding me back would be the 4.30 but I'm looking into the idea of changing out the ring & pinions for a 3.73. I know that would be costly but this will probably be my last truck, might as well get what I want.

Face Down · 10-16-2015, 07:07 PM

4:10 GR.....approx 2100 at that speed towing or not.

C130 · 10-18-2015, 02:09 PM

Quote:

Originally Posted by Cyncwby

C130.....thanks for the info, I'm assuming you were in the Air Force and was a pilot or crew chief. I love the C-130, man what a plane .... and they are pretty sweet with a 105, 40 mm and gatling guns a' blazin.

Anywho, yep the F-450 would be my choice cuzz it does look nasty alright. The only thing holding me back would be the 4.30 but I'm looking into the idea of changing out the ring & pinions for a 3.73. I know that would be costly but this will probably be my last truck, might as well get what I want.

Pilot, never flew the gunship but that is one cool plane! Good luck with your truck decision. I love the 4.3 towing but would like the 3.73 for driving to work daily for sure.

Cyncwby · 10-22-2015, 04:55 PM

C-130 .... yea I'm a Viet Nam vet (67-68), saw the 130 everywhere over there ...... question, I read that the 2011-2014 "exhaust brake" as Ford calls it didn't work too well and that's one of the reasons Ford went to the single bigger turbo. So, how does your rig respond when you push your slow down button? I've got a real exhaust retarder on my 7.3 (Pacbrake) and man it REALLY will slow you down. I can come down a 6% grade and never touch my brakes...... very comforting .

gearhead · 10-22-2015, 06:43 PM

If I remember right, the FX4 package includes 4.30 gears. So, if you want 3.73 gears and 4 wheel drive just get the regular 4 wheel drive model.
I'm running 3.55 pulling 11,500 and it does good. I sometimes lock out 6th if I'm in a 50-60 mph speed zone. Just to keep the rpm's up for better throttle response. Usually get 10.5 to 12 mpg towing. 17-18 on freeway empty.
Also, read the owners manual real good. Ford "recommends" 5w-40 CJ4 oil if towing. All oils that spec are synthetics, that I have found. Ford dealer will want to use regular Motorcraft 10-30. Shell Rotella 5w-40 synthetic in mine.

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