Haha, I love a little competition here and there. We get the two supporters of the forum to dissagree is always a good thing because then we all benefit from it.

My question to you is, will putting gears on my 05 Ram Hemi void my 7 year 70k mile warrenty?

 

I'm wanting to swap out my gears to 4.56's to gain back what I lost when I lifted my truck and put 35's on it. I have a question though, I have a non slip diff, does changing gears alter the non slip diff, or are they completely seperate from each other? Also, about how much does it cost to swap out my 3.92s with 4.56s in a 2wd, parts and labor included? I'm guessing around $400? Any help is appreciated. Thanks.

 

I've always been told that higher gears puts a lot of wear and tear on your engine. I got 3.55s in mine and it does real well. I would like to have the 4.56s in for the trailer though.

 

What everyone forgets in this great debate about gears and mpg, is that 4.56's are going to put more power to the pavement. I don't know about you guys, but if I can put more power to the ground, I'm going to use it. Meaning, I'll be on the gas more. I don't know one person who ever got 4.56's for the mpg increase. Not one. It may be a product of the gear change, but that was never there sole intention. They did it to improve acceleration, low end power, etc.

It is like this with all modifications. Exhaust companies say their muffler increases fuel efficiency x amount. Well, being guys with big engines, we like to hear that exhaust purr when we are cruising. So, we give a little gas here and there. Or, we buy a Superchips programmer, so that we can have more power for towing, tune for 87 octane, etc. Well, thats all fine and dandy, but you immediately realize that the torque management system is gone, and there we go again laying on the gas pedal.

Its all BS to me. We have 3 options when it comes to saving gas: 1) Buy a car. 2) Drive our trucks less. 3) Drive like grandma and grandpa. Otherwise, be prepared for crappy gas mileage.

 

gears do not alter the limited slip. I would recommend a aftermarket posi loc system, If you do a search you will find alot of ram trucks that the rear ends fall apart. I believe it is this factory trac-lock system that is falling apart. Auburn lockers is one that compares to clutch type, doesn't click or clack when turning. and don't skimp get new bearings and seals.
And yeah they will Always help out with towing

 

i know im gonna look like an idiot but how in the heck is he gonna just "add a 4.56 tohis truck"? is he buying a whole new transmission!? if so, he is rich!

 

No change to non-slip unit. You're just replacing ring gear and pinion gear. These two gears will cost you $170-220, depends on manufacturer (Motive Gear, Richmond Gear, Genuine Gear, Yukon and more). The master install kit (highly recommended) will set you back $50-100. Add to this 3-4 hours of labor cost and new diff fluid.

 

It is always best to find things out for yourself.

Some questions to ask yourself about Rams and gear ratios...

1. If a friend and I both go to a Dodge dealership with cell phones and test drive a 4.56 diff equipped 5.7V8 'PowerWagon' against a following 3.55 diff equipped 5.7V8 Ram at the same speed on the same road in the same weather - wouldn't that tell you something about whether higher gear ratio helps MPG? (add weight to make the trucks the same for the best test)
Taking extra friends and having a 6 speed 4.7V8 equipped truck follow that PowerWagon and the Hemi Ram would give even better information, as would having a 3.7V6 Ram follow as a fourth truck. There is great information in a 'convoy' test.

2. If higher gear ratios improve MPG, why doesn't my MPG go up on the highway at cruise when (depending on model year) I lockout OD or put it into Tow/Haul?

3. If I pick a speed like 55 mph where I can go the same speed in 2nd, 3rd, 0.75 or 0.67 overdrive gears, what are the MPGs on the overhead trip computer like at the various RPMs? If I graph these MPGs do they lie along a straight line or do they make an arc? If I extend the arc upward, what RPM does the MPG 'top out' ? If I look on this graph for the rpm that 4.56 differential gears would give me at highway cruise does it show my MPG will go up or down?

4. Why does Dodge make the 0.67 top overdrive available on the 545RFE automatic tranamission used behind the 5.7 Hemi V8, but locks this gear out and makes it unavailable on the 45RFE trans used behind the 4.7V8 and only use the 0.75 as top gear?

5. Why does Nissan choose a 3.36 differential behind the 5.6V8 but Honda chooses a 4.53 behind the 3.5L V6? Does the top gear overdrive ratio matter? What % change between gears do Nissan and Honda choose. What % change behind gears does Dodge choose?

6. Is it stupid to talk over and over about differential gear ratios when it is the miles per hour for each 1000 rpms that really tells you the gearing? Aren't the gears in the trans, the gear in the diff, and tires all part of a 'system'?

7. A Nissan Murano has a 'continuously variable transmission' that sets the ratios to whatever is best for either acceleration or fuel economy. At what rpm does it cruise on the highway? At what rpm does it accelerate?

8. Why did Dodge buy a smaller version of this CVT (made by Nissan subsidary JATCO) for the new Dodge Nitro?

9. If you were to attach a vacuum gauge to the engines of different vehicles at highway cruise speed, would they all be running similar vacuum readings of around 4-6 inches of mercury? Why is this? Why wouldn't running at 15 inches of vacuum be better, or running at 1 inch vacuum?

10. Do automotive engineers set up vehicles to get the best MPG at highway cruise,
or do they set up the gear ratios to 'feel strong' on hills and accelerate fast so that the vehicle will sell well ? If a vehicle gets slightly better MPG but doesn't sell well will the engineer be employed for long?

 

Yes.

 

I have a Powerwagon with 4.56 And the factory 33" tires. Its a 5speed auto and Im getting 11.0 MPG city/highway.