I switched from 3.92s to 4.56s, and before the switch, my fuel economy averages were 13/18.5, hand calculated. After the switch, my averages are 14/18. In town, the gears give you a greater mechanical advantage during acceleration, so your engine isn't using as much fuel to get you moving. I lost about .5 mpg on the highway (cruising around 70mph) simply because I'm turning 2500rpm vs 2200rpm. However, power is much smoother, the transmission no longer gear hunts constantly, and it always seems to have power on tap. And despite running 300rpms faster at 70mph, the engine is running cooler, which I attribute to the fact it's into it's power band, instead of straining to keep 6,000 pounds of truck moving. This is under normal driving conditions though, larger gears will burn up way more gas if you are hot ******* it. After my gears broke in, I was driving it like I stole it, and got 8.8mpg average on that tank.

 

Thanks for the replies so far. I like it when the experience comes to the front.

What started my question was I wsa having a talk with a neighbor who does quite a bit of wrenching w/his son on their muddin' trucks and his diesels he tows with. When I mentioned a desire to switch from 3.55 to 4.10 he expressed concern I might be getting poor gas mileage afterwards. Again, why make a change if I am adding a problem to the overall equation ...

Anyway, understanding how my truck now performs, I revisited my desire to change the gears. Using a gear calculator, I know that on the upper end, around 70mph and 5th gear, I will increase rpm about 200revs ... not huge in my mind.

If I can expect, based on others experience, that I won't add a huge concern about mileage, then the 4.10 is worth my money.

By the way Pyro ... I do like those Classic II's!
I just may have to sell off something to get em' sooner!

 

I understand your neighbors concerns, but the Ram is different form "old school" logic on the gear issue. There are many factors that come into play.
The Ram is going to suck off the line unless you get into the transmission and change the actual 1st/2nd/3rd..etc gear ratio's. It's those ratio's that the ram sucks off the line. Your just changing the last guy standing because....That's what we all do. Other manufacturers go numerically higher on the lower tranny gears and numerically lower on the rear gears(F-150). The Ram is opposite.
I think for your purpose and the fact you have a Manual trans. I would def. go with the 4:10's. I think you would be able to cruise in 5th gear on the highway and only need to drop into 4th going up hills. Or be able to run 4th around town at 45mph with out ever dropping into 3rd as i assume that is the case right now?
4:56's would be a real eye opener for that 4.7L, BUT I think it may be a little to jerky as far as Daily shifting goes or maybe even the fact of shifting too quick. i went 4:10's over 4:56's in my stang because i didn't want to shift out of first while i was under the traffic light. i wanted to go a few hundred feet before shifting.(That's another thing to look out for when you get into 4:56's...etc)
I'm not trying to steer you away from them, just want you to realize what you are getting into with an expense that high. Its good to know what to expect! I would like to hear what MANUAL tranny guys have to say about gear changes in their Ram as far as first gear being useless on the road or having a herky jerking shifting ride because of all that additional torque transfer. Your installer will need to grind out the case a teeny bit to fir the 4:56's. Not the 4:10's. I would HIGHLY reccomend buying an aftermarket limted slip and get that stock junk out if you do have it. You can get an Auburn unit for under $400.

I have 3:92's and plan on going 4:56's(5.7L w/auto)

Last but not least....Don't have your neighbor do the install. Have a shop do it. That is only asking for trouble down the road wether it's your truck that has issue's or the simple arguement... Neighbor war....lol

 

in the ol ram i had 3.92's went to 4.56's really liked the set up
even thow they werent even broke in yet (didnt really get a chance to stomp on them that much sold it )

now i have 4.10's in the MC and i like them beter than the 4.56's in the ol truck but thats apples vs oranges sincle cab short bed vs megacab

i agree with most on hear no real mpg difference just rpm and it is a biotch off the line lol witch i like feels like i have allot more power.

 

...I went the 3.92's to 4.56's to 4.10's.... your engine and drivetrain will love you for it (as if they had feelings)... the 4.56's was one of the funnest mods i did at the beginning of my modding process... city driving was always exciting, I only went to 4.10's because the 4.56's went bad (due to incorrect installation) and because I wanted to see how well 10's would do at the track (as I have modded more thus negating the need for a lower gear ratio...and, give me better top end at the track)....

 

Thanks for the last 3 posts.
The first gear on my tranny is low ... 4.10 would make it a killer off the line and intial take-off when the horse trailer is hooked up. How/when 2,3,4 won't really be as critical in daily driving to me ... I try to float the engine around 1500-1800 unless I have a load on ... shifting around 2500rpm most times.
I'm leaning more positive in the 4.10 change now ... I like it better getting the practical experience rather than "it should" scenario.

 

like i said i love my 4.10's over the 4.56's its your call

 

I went with 4:56 gears and i originally had 3:92 and it made a huge difference but as far as mileage goes,it did drop a little but not a huge difference.
Personally I would go with 4:56's if you have a 4.7 with a quadcab.

 

Got 4.10's and there incredible! I wouldent change them for the world!

 

Auto trannies in 3rd gen Rams have two overdrives, with your manual transmission, unlike the automatic guys, I think you'll see the best power/ mpg balance out of 4.10s...

BTW, 4.56's here and like Pyro, about a 1-1.5 mpg gain in town and about a .5 mpg loss on the interstates, mainly up over 75 mph...