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was wondering what the best set of gears is for towing. I tow a 21 foot BIG FOOT 5th wheel. I think my truck has 3.55's now. :help:
 

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For towing only, or for towing only once in a while? With a 5 speed auto tranny, I would opt for the 4.56 gearing. I did this to my 4.7 with auto about a year ago. It made all the difference in the world while towing our trailer. We have a similar sized trailer. If I had a 4 speed auto, I would go with the 4.10 gearing. This is only because of the final drive RPMs while running on the interstate. The 5 speed has the extra overdrive gear that keeps the RPMs reasonable with the 4.56 gears.

We took a 2500 mile round trip with our trailer last summer. As soon as we got back, I started looking around for a shop to do the gear swap. I wish I had done it BEFORE that trip. It makes the truck a lot more fun to drive, with or without the trailer.
 

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zacharyzoo said:
was wondering what the best set of gears is for towing. I tow a 21 foot BIG FOOT 5th wheel. I think my truck has 3.55's now. :help:
What is the weight of your 5th wheel? 1500's are not usually used to tow a 5'er. Upgrading gears is only one small piece of the puzzle when it comes to towing a 5th wheel.
 

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Valdez Racing Team
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4.56's bro...then you won't lug up grades an stuff...engine will last longer with less "work" on the drive train...I tow my boat alot and have 110k hard miles on mine and it still runs strong...I had switched to 4.10's about a month ago but I'm going back to 4.56's before next boating season...
 

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DELTARAM
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As rpound said....4 spd 4:10
5 spd 4:56
 

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4.56s for towing

rpounds said:
For towing only, or for towing only once in a while? With a 5 speed auto tranny, I would opt for the 4.56 gearing. I did this to my 4.7 with auto about a year ago. It made all the difference in the world while towing our trailer. We have a similar sized trailer. If I had a 4 speed auto, I would go with the 4.10 gearing. This is only because of the final drive RPMs while running on the interstate. The 5 speed has the extra overdrive gear that keeps the RPMs reasonable with the 4.56 gears.

It makes the truck a lot more fun to drive, with or without the trailer.
I agree completely.....I have 4.56s and would not have bought anything different, not even 4.10s. They work great with the 5 spd auto and the Hemi.
 

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I like my 3.73 ratio on the highway. Direct at 65mph puts it at 2600rpm and for the steeper hills, 2nd gear is at 42-4500rpm right at peak torque for 300 advertised flywheel horsepower. Unless you're afraid of it and pussy foot the loud peddle, it WILL get the job done with ease. We just returned from our Christmas visit vacation and traffic was thick and moving fast. To keep from causing too much of a traffic jamb, I set the cruise on 70mph. 2800rpm in direct, 2100rpm in O/D on the flats and 4800rpm in 2nd on the steeper uphills. I use cruise because it's tiring trying to feather the peddle trying to make it do what I want it to do when IT knows what it needs to do while I steer. It will not hurt the engine to run it in it's power band. Driver perception is not an engine problem or weakness. It's a driver perception problem. My driver perception cringe starts at 5k rpm. After four Cummins powered Rams groaning along at 1750-2900rpm on the same routes towing the same 5th wheel, it took a little getting used to towing with an engine that revs again. Once over the unfounded cringe factor, it sounds good to hear the occasional hot rod music while towing. At 75k miles, it still runs great and burns it's usual 1/2 qt between 5k mile oil changes using Mobil-1 5w-20 or 5w-30.
 

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I like my 3.73 ratio on the highway
Good choice for a Hemi. Bad choice for the 4.7. The smaller engine needs the torque multiplication created by the steeper gears.
 

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The 5.7L benefits from the 4.56's as well... You will find that it just holds the OD going up hills rather then stepping down to a lower gear. I know my 4.7L will hold OD going up some pretty steep hills without stepping out of OD... it just holds the gear all the way up the mountain.

RPMs alone do not dictate fuel economy... Its the load on the engine at any given RPM that you need to be concerned with if your after MPG. So just because your RPMs are lower it does NOT mean that your getting better fuel economy had they been 300-400 RPMs higher. Lugging the engine too low of an RPM can and will HURT fuel economy... And unfortunately the factory has set our trucks up to LUG.

SPEED SAFE, AIR RAM
 

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RPMs alone do not dictate fuel economy... Its the load on the engine at any given RPM that you need to be concerned with if your after MPG
Absolutely true, at least up to a point. The same is true of engine wear and tear. I've seen some elaborate write ups on how much faster an engine wears based upon RPM. Hogwash. Engine loading has much more to do with wear. Besides, most wear occurs at cold start up.

Lower gears = greater torque at the rear wheels which = less power necessary to move a load which = greater mileage - again, up to a point. I'm getting significantly better mileage with the 4.56 gearing than I did with the stock 3.55s. Would I have done better with 4.10s? Maybe . . . I'll never know, cuz there's no way I'll ever go back!! :rck:
 

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Rear gears are only part of the equation. With 4.56 gears, I'd be towing at lower rpm than with the 3.73. Overdrive was not intended as a towing gear. It's intention is to give better mileage while cruising lightly loaded. Overdrive only became a towing gear when diesels came along and O/D was needed to keep from over revving the engine while providing enough gear reduction for launches.
At 65mph with the 3.73, I'm turning 2100rpm in 4th .75 O/D. In direct I'm turning 2600rpm. In second I'm turning 4500rpm for the steeper uphills. 2600rpm is good for towing on the flats to rolling interstate hills. 4500rpm in 2nd is perfect for the steeper interstate uphills. And I still have 1900rpm at 70mph running empty for better mileage. The only place the 3.73 might be a problem would be on a launch up a 20% grade with our load.
A 4.56 ratio would mean I either run 2400rpm in 4th or 3400rpm in direct towing. 2400 would probably be fine but for the steeper interstate hills, 3400rpm in direct might not be enough and 2nd would be over 5600rpm.
So at 65mph with stock size tires, there's more torque/horsepower available to the rear wheels with the 3.73 ratio.
 

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locogk
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i have a 06 with tow or haul mode is it a 4 speed or 5 speed
 

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Locogk,

You should have a 5 speed, if running an auto.

HemiRoy,

I agree, with a Hemi, I personally would not have gone with the 4:56 gearing. My personal choice would have been 3:92s with that engine. The Hemi has a lot more grunt than the 4.7. But the original poster is running the 4.7 and is asking about gears for his setup. Experience tells me that he will be very happy with the 4:56 gears with the 5 speed tranny.

Why? Because we have limited torque in the 4.7 and it makes it's peak in a pretty high rpm range (as does the Hemi, but the Hemi has more torque over a broader rpm range). If the OP is running stock 3:55 gearing, he can up his available rear wheel torque by over 20% in every transmission gear by going to 4:56 gears. (4:56-3:55)/4:56. He will be much happier with that added torque while pulling a trailer. Yes, he'll slow down on the hills in order to keep in a comfortable rpm range. But he would slow down from lack of power with the stock gears anyway. But on a rolling interstate, he'll hold 4th, rather than going back and forth between 4th and 3rd. The newer trucks have the ability to lock out 4th gear (I believe this is true, someone correct me if I'm wrong). In the '04 model however, tow/haul only locks out 5th gear. 4th is way too tall to hold with the 4.7 while towing. The slightest rise and the tranny will shift to third, pick up speed and then back to 4th. There's no way around it in the '04. With 4:56 gears, the tranny will hold 4th on all but the steeper hills. A good combo for the 4.7.

Tranny temps also run lower. Why? Because the transmission shifts much less and there is less load on the tranny. The torque multiplication with the lower rear gears puts less stress on the transmission components at any given load. Where I was running 190-200 degrees on the tranny before, I'm now running 150-160, an added benefit when towing with a 4.7.

So for the original poster with a 4.7, I can tell you from my personal experience pulling a similar trailer, that truck is going to wear your nerves thin. If you go with the 4:56 gearing, you'll be much happier with your truck all the way around, even in the fuel mileage department :)
 

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Valdez Racing Team
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I'd agree if i never had 4.56's installed on my hemi...i ran almost 2 years and 80k miles with 4.56's, I love the street as well as the towing characteristics... I went to 4.10's thinkn I'd get a little mileage back... I've never been more dissapointed... if I never did 4.56's I'd say 3.92's an 4.10's would be good...but after tasting the 4.56's... i wished I never changed them out...
 

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Valdez Racing Team
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...it's one of those things...if you do the math you would think that 4.56's are too steep... but the variable not taking in consideration like Nick says is the less wear and load on the engine and drivetrain... when I towed my boat with 4.56's..it literally felt like my 3.92's with nothing behind the truck...that's how easy it felt like...
 

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locogk
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thanks for the info i may have to look into changing my gearing what kinda price range do you think it will be to change out my gears

thanks

loco
 

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id suggest an e fan too. my temps rise a tick or too when towing and turning 3000 rpms in 3rd, or 3500 at 70mph.

chefred: is that 110,000 km? or 110,000 thousand miles?
 

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Valdez Racing Team
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iv got 110K MILES on my 05...I love to drive... typically gears cost between $185ish to $225.00 and depending where you go, install is around $250.00 (2wd)..
 

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locogk
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thanks for all the info i will check on a place near me to change the ratio

thanks all

loco
 

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I do lots of highway driving and the only time I would recommend the 4.10's over the 4.56's is if you do a considerable amount of highway driving and only if you have tires larger than factory but smaller than 35's. I think thats fair too say. At 70MPH on the highway I get 16MPG at 2400RPM's w/ 33"s 12in wide. If I had the 4.10's I think I would see an increase in MPG since I have the 4-spd auto and obviously lower RPM's at 70MPH. If you do an equal amount of highway/road driving definitely go with the 4.56's if you have the 4 or 5spd auto and tires larger than factory or tow.
 
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