3.55 gears to 4.56 gears

2010Sport4x4 · Apr 11, 2011

Hello everyone, I'm a newbie and thought I would join the RAMForum to get some opinions on gear swaps for the 4th Gen Rams.

I have a 2010, Sport 4x4 with the 5.7 and currently 3.55 gears (and the 20" wheels with 33" tires). He's kind of a dog and any little hill or bit of wind results in a down-shift.

I'm averaging about 15.5 mpg and probably drive 70% city 30% highway. If I put a load or if there is a breeze (even a small one :drool:

) that drops to about 13mpg.

Has anyone done a gear swap on their 4th gen RAM? If so what did you go to and what results did you see?

I'm about to order 4.56 gears but wanted to make sure it doesn't ruin mpg. I've read a lot of stuff to where it will actually improve in-city mpg, and highway stays about the same as long as you run 70 to 75mph.

Any shared experiences would be great!

zuiquan1 · Apr 11, 2011

I'm doing the same swap! I've heard nothing but good things from people, I cant wait!

Where are you buying your gears from? Theres a group buy going on right now for gears from 3rd Strike, some awesome prices, now's the time!

Welcome to the forum BTW

2010Sport4x4 · Apr 11, 2011

Cool thanks man, is that a pic of your truck? That's the same color as mine, but I don't have that badass hood!

What's involved with the group buy? What brand of gears are you looking at? I was going to do US gear in the front and Yukon in the back.

Oh and I was working with Wayne over at Diffsonly.com.

2010Sport4x4 · Apr 11, 2011

Thanks for the greeting BigHorn.

37's and 3.55s are probably good for you. Me, I'm just a picky *******, I can't stand all the down shifting it does..... I do a fair amount of pulling too.

This chart is pretty good, shows the rpms at a 1 to 1 ratio with tire size and gearing. Chart Gear Ratio

The Assassin · Apr 11, 2011

Welcome! Check out the prices on our group buy. There is a link in my sig.

2010Sport4x4 · Apr 12, 2011

Lol, knowing that it was a GMC makes me smile! hahaha

Just curious Bighorn, what brand is your lift on your truck? It's a damn good looking truck man!

Musclemckeester · May 7, 2011

BigHorn 4 Life said:
I don't see how it could be a dog with just 33" tires.I have 3.55 gears on mine and I am running 37's she runs awesome.

I have 100k mile powertrain warranty and if I were to do a gear swap then byby to warranty.

Welcome to the forums BTY.

Changing out the gears screws the warranty? I was really leaning towards 4.56 gears myself but not if it's going to void the warranty.

0212353 · May 7, 2011

they won't warranty the gears - but they can't void your entire warranty for it.

Kevin, you are looking at a fat bill on that too.......front and rear gears, not cheap!

Musclemckeester · May 7, 2011

Was about a grand for my brother to have his Rubicon regeared. I anticipated roughy same. I did loose noticeable power when I went to 35s.

0212353 · May 7, 2011

a grand seems VERY cheap........

Musclemckeester · May 8, 2011

Well that was a couple years ago and it is a Jeep. It was just another idea I was throwing around. Now I'm curious... I'll have to at least call and get a quote.

2010Sport4x4 · May 9, 2011

Yea a grand would be a great price to get them installed.

I got mine installed this weekend. My buddy owns a shop and he did them for me. We had a heck of a time installing the 4.56 ring gear into the rear. It was so fat that the edge of the gears were rubbing the inside of the case. We had to shave the edges down a little. Then the center pin for the spider gears wouldn't go in, because the ring was too fat. We had to modify the center pin (which may not be a good idea, I don't know).

Anyone know what the problem may have been? Should I have bought a new carrier for the rear? It could be my fault for using the stock carrier.

Front went in without a hitch. I put USA gears in the front and Yukon in the rear.

On the upside however, the truck is a completely different animal. No more down shifting on little hills, lots of power and I'm averaging (at least today) 16.2mpg in stop and go driving. (used to be 14.5) It seems more balanced now, really wish Dodge would have just done at least 4.10's factory with those 20" wheels and 33" tires.

Anyone else put that big of ratio in their truck? I'm kind of just waiting to see if the rear end blows up or not :-/

Musclemckeester · May 9, 2011

Was there a big increase in power off the line?

2010Sport4x4 · May 9, 2011

yea there is a noticeable power increase especially off the line

KGBIGCOUNTRY · May 9, 2011

Havent done a set yet but I know they are sopp to be heat cycled. The housings have to be ground on 07 up I think??? and far as the pin I think a few companys sold a pre modified one.

2010Sport4x4 · May 9, 2011

Ok, so after doing some research and talking to a couple guys who sell gears, here is the answer to my question:

4.11 and up gears require either shaving one tooth down to allow the center pin in or buying a notched one: CHRYSLER 9.25" NOTCHED CROSS PIN (like KGBIGCOUNTRY said, thx man)

4.56 and 4.88 gears do require modification to the gears or to the housing to fit the newer 1500's

Doesn't seem to be an issue with needing a new/different carrier

So my plan is to get that notched pin and just replace the one we modified. I plan on towing with the truck, so I don't want any weak spots.

I will keep everyone posted as the gears break in. I'm sure the power and mileage will only get better!

zuiquan1 · May 9, 2011

Good info! I got some 4.56's on order, want to have everything I need when I get em installed.

TheSatinPumpkin · May 9, 2011

Good Mod.

2010Sport4x4 · May 23, 2011

Hey just wanted to keep you guys posted. This is the best mod I've done so far. Yes it is expensive, but I'm averaging 17.2mpg (according to the display). The thing never down-shifts on hills and the MDS (eco light) is on A LOT.......... To top all that off, the truck has some serious balls now. I'm just really wondering why Dodge didn't do this from the factory? It makes no sense, I was averaging about 13.8 in town and 15.5 highway with the 3.55's, now I'm up to 17??? what the hell!

I highly recommend at least putting 4.10s in your truck, if you have the factory 20" wheels and the 33" tires.

My most recent average was 17.2mpg yesterday after a 200 mile round trip (highway) to the lake and back........ so highway has gone up as well as city. I live in Missouri/Kansas, so we always have a head wind and hills on the highway. The damn thing used to down-shift all the time with a head wind.......... it doesn't now though

BlackedOutHemi · May 23, 2011

Awesome. Haha. I believe this is going to be my next mod.

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3.55 gears to 4.56 gears

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