3.71 vs. 4.10 rear axle

[danmcguire]

After pulling a 5th wheel 20,00 miles in last 2 1/2 years,I have decided that my 3. 54:1 rear axle is too high ratio for pulling many of the mountainous area that we like to visit. I am planning to have Desert Diesel in Tucson change it out for either 3. 74 or the 4. 10. Living in Seattle, we do a lot iof pulling over the mountains and I think I would prefer the 4. 10, but have concerns about high rpms (noisy, etc) when driving at 70-75 unloaded. What do those of you who have 4. 10s feel about them? Would you buy that rear end again or go with 3. 7:1s? Would I notice much difference going to the 3. 71s. This Dodge is the only truck I have ever owned, so I really don't know what to expect. We have pulled a 9000 (wet and loaded) 5th wheel for two years, but am trading up to a 9000# dry wt. Montana 2955 and I am tired of getting to the top of mountain passes doing 35 mph! I run stock except for K&N filter.

 

[Blakers]

I would think it would be much more cost effective to increase your power than to change gear ratios. This is especially true if you have a 4x4. With more power you won't lose your highway speed and you'll fly up the hills even with 3. 54s.



Now granted, my travel trailer is only 5500 lbs. , but I could set the cruise and go up and down the mountains in West Virginia in OD at 70 mph with hardly knowing it was there. And I have 3. 54s.



Blake

 

[BigMike]

See my signature. I have no problem pulling 12K plus up 6% grade at 50 mph in 4th gear if I keep my RPMs up. I'd settle for 40. I like the 3. 55 when I'm not towing, which is most of the time.

 

[jerryrigg]

The difference between 3. 54 and 3. 71 is pretty small you can easily achieve almost the same effect by going to a slightly smaller tire. The 4. 10 will give you more guts at a cost in fuel mileage. You said you did 20K in 2 1/2 years. . that really is not a lot of miles, do you also use the truck as your daily driver? if so mileage also becomes an issue. I'd consider some engine mods first if this is your daily driver, an EZ, injectors, open the exhaust. This will help the mileage and make hills easier when loaded down.



just my 2 cents

-Matt

 

[Blakers]

Dan,



You didn't say how many valves your engine has. What transmission?



Blake

 

[QRTRHRS]

Why not put that money into an auxillery underdrive transmission? Give you the best of both worlds. At 70-75 mph with 4. 10's, that engine gets to humming pretty good, take my word for it.

 

[Blakers]

Originally posted by QRTRHRS

Why not put that money into an auxillery underdrive transmission? Give you the best of both worlds. At 70-75 mph with 4. 10's, that engine gets to humming pretty good, take my word for it.

If you don't have the power, you don't have the power. Another transmission is not going to give him more power. For the money he can give himself at least a hundred more horsepower without messing with gears at all. Then the truck will be more fun for all uses.

 

[klenger]

If you're going to spend the money to change the ratios, I'd definetly go with the 4. 10's They are great for towing. I rarely drive mine for any extended miles on the highway unless I'm towing, so I don't have a problem with them. Overall, the milage won't change that much, but your towing pleasure will.

 

[pwr2tow]

For towing purposes I think I would have been money ahead to just change out the gears to 4:10's and leave everything else alone. I like to race once in awhile and tow both so I done what is in my signature and I have the best of both worlds.



Gear torque multiplication is great for towing and it brings the rpm's up to where you have available HP. Add a small box or injectors to the combination and you have a great towing machine.



Ron

 

[pwr2tow]

Dan,



You should create a profile of your truck, that way us guys out here can answer your questions better.



EDIT:: Silly me, I forgot to tell you how to do it.



Go to (user cp) at the top of the page and click on it, and when the new window pops up click on (edit profile) and scroll down to signature, type in whatever you want us to read each time you make a post to the forums.



Ron

 

[mschoenheider]

I am in the process of assembling the parts and tools to swap my 4. 10s for 3. 55s. I just returned from a 2000 mile trip pulling 11K, and I always had more power than I needed, the problem was that in my opinion, I was turning too many rpms while going 75 down the highway in OD. The 4. 10s will give you 15% more rpms for the same road speed and transmission gear. Depending on your truck, you will most likely be able to pull slightly faster with the 4. 10, but the conversion will be expensive. I priced out parts alone for my 2 wheel drive, and they came out to a little over $1200 for a carrier, gears and new bearings. You can get substantially better towing performance from power upgrades for this price. If you have a 4 wheel drive, your front axle parts (Dana 60) will be slightly cheaper than the rear (Dana 80). Add the installation costs to the price of parts, and it gets expensive quick. My $. 02 says go with power upgrades.

Mark

 

[Blacksdieselhp]

I've had 6 Dodge/Cummins trucks since 1999 and I would definately stick with the 3. 54. I've had 2 auto's (3. 54/4. 10), 2 5 speeds(3. 54,4. 10) and 2 6 speeds(3. 54/4. 10). I have a horse trailer with full living quarters and it wieghs 26,000 lbs with three horses on it. The truck I pull with now is a 2001 6 speed with 3. 54's. I use an edge ez and 275 injectors. I just got back from Idaho( I live in Ga. ) and I could gain speed up any hill I crossed. I went from 7. 9 mpg to 10. 2mpg with edge ez. With out a load I get 18-20 mpg depending if Im in town or interstate. My 6 speed with 4. 10s only got 12 without a load.

 

[Barry]

Dan, we simply do not have enough information on your truck to make a recommendation. Pls. tell us:



Year and model



12 or 24 valve



Tire size



Transmission type

 

[Steve M]

I like my 3. 54s. I had a '95 auto/3. 54, then a '98 5spd/4. 10 and now another auto/3. 54. It tows great with O/D locked out at 68mph/2700rpm. Hills and headwinds are no match for it. It even smooths out and sounds quieter at 2700rpm than it does at 2500rpm. It's bone stock 235hp/460 lbft. I get the same 10-11 mpg with O/D locked at as I do in O/D with my foot to the floor bogging along at 1800rpm. I use O/D when there's no headwinds or hills.

 

[Wolfgang]

I have the same trailer you are talking about buying and even before I did the mods I went up 6% grades at 50. See my profile for mods I have done. Currently I go up any 6% grade at 65 and I am only limited by my EGT's or I could pull faster. Personally I am very happy with my 354's and would not want to sacrifice the gas mileage I get with them.

 

[mcandies]

Dan,



I pull a 10,000 lb. 31' fifth wheel and never go over 65 mph while towing. RPM's at this speed are around 2050. Without the trailer at 70 - 75 mph they climb to around 2250 - 2300. The mpg's while towing at 60 - 65 usually run around 12 - 13. When using my truck locally, (light), I consistantly get 19 mpg's. Would I get the 4. 10's again, YES!

 

[Steve M]

Marshall, the 4. 10 sounds perfect for 65-70mph. I wish I could get there without major expense. On the other hand, aren't you in the same boat at 55mph in the hills with 3rd and O/D being so far apart? I liked my 5spd/4. 10 but it was 2500rpm at 70mph loaded or not all day long. The 4. 10 sounds like a better match for the automatic. I like 2250rpm but that's 58mph for me. 65mph is either 1750 or 2500.

 

[MBurtch]

I have a 99 six speed with 354 rear end with EZ and gauges. I pull a 9,000 pound 5-th wheel around Montana. I drove from Sheridan, WY on the freeway to Three Forks, MT and never shifted out of six gear. Just my two cents worth.

 

[Blakers]

I think some of this depends on whether you have a 24v or 12v. I never drove a 24v, but from what I hear they like to scream a lot more than the 12v. Maybe you like running over 2000 all the time, but I would get tired of it. My truck runs great at about 1800 rpm, which is about 70 mph with 3. 54 and 265 tires. It pulls fine down to about 1200 rpm, but I have to watch the egts. To me the 4. 10 gears would be fine for a local hauling truck like a dump truck, and they'd be great for running 38" tires.



Did the originator of this thread ever say what engine he has in his or what year it is?



Blake

 

[klenger]

Did the originator of this thread ever say what engine he has in his or what year it is?

Who cares, after three replies on this forum, the originator has to give up and go get his answer somewhere else anyway.