I am tempted to go the extreme, 2.76, how would they drive? Right now i flat out floor my truck and ride it to 45 in first, 85 in second, 3rd and 4th well ive been to chicken to try.

 

You dont want better acceleration? The lower the number the less bottom end. The higher the number the better bottom end but not as high top end. Like me and my buddy have the exact same trucks but he has 3.55's I have 4.10's. I top out at 95-100 where he tops out at 115-120.

 

The main thing I want is more mpg, this truck has plenty of pep, it does 0-60 in 6 seconds. I try to drive it nice now though since gas rose 50 cents a gallon in less then 5 months here, I cant believe just 2 years ago I was looking at a $1.98 for unleaded and $1.75 for diesel, now its $3.73, and $4.15

Or would the 4.10s be better? Im thinking that I cant even top out the truck in 3rd so in od I shouldnt have any speed limitations by gearing. And how do you disable the 110 mph governor? Theres a 2 mile air strip that opens one day every summer for people to take their cars to the max. I wana break 110 this year

 

Get a sct tuner it will wake that beast up. I would leave gearing where its at cause if you do city driving then stop and go will kill the mpg because it will have to work harder to get moving again. Your not really gonna squeeze much more out of the 5.2 with a auto anyway.

 

Other things also play a role in that, not just the final gear ratio, i have 3.7 final and i have gone well beyond 120




Then you want a better gear ratio that doesn't make the motor work harder to get to speed. If you have 3.55's and go to 4.10 you should save a little, then there are other things you can do and change to increase mileage


That's wrong and backwards, it is harder to get going with a tall gear vs a short gear

Lets think about this for a moment.....

If your theory is correct than why not just drop it right in 3rd gear and go.....

It's harder to move with a dead gear and it takes more energy to move.

 

We are talking apples to oranges. You are in a dakota im in a ram with a 5.9 ho diesel with a 6 speed(about 380 hp and 800lb of torque). I red line at 3,300 there for I have no room left to push my mph any higher. Now if I had 3.55's instead of 4.10s the 3.55's would drop my rpms lower and let me be able to get going faster till I redline. The lower the gear number(ect 3.55's) will work harder to get going from a stop then the same truck that has 4.56's. My truck is equipped with the camper package which upgrades you to 4.10's for easier start outs when hauling.

 

No the 3.7 ratio i referred was is my cummins not my dakota which is 4.10 and im not done or out of motor at 120mph with my cummins.

 

Depends on your tranny and year of your cummins. But either way my point still stands that at 4.10's im out of rpm range.

 

same here thinking on the change

My Dakota has the 2.5 engine the AX-15 5 speed and the 3.55 axel I love everything about it except my take off from a stop power it kind of lags but she loves 4 and 5 gear on the freeway I can easily top 95 to 100 if I want to could get away with it and my gas MPG is great on the freeway.

So my problem is gears 1 to 3 just don’t have good strong power in them with the 2.5 engine trans 3.55 rear. I wanted to change up to 3.91 geared rear-end but decided that would kill my freeway driving so now Im thinking on just upping one notch to 3.75 rear end even though that’s not much of a change at all.. I just want some more power in the low gears for stop and go city driving.

I still may go with the 3.91 because I want to go to a 30 tall tire, now I use 28.5 tall tires I think or they were 29 tall.

 

I would go 3.92 if you're going to a 30" tire, you also should check the weight of the tire that as well as the diameter will kill your mpg.

The 55 to the 92 isn't a great big jump unless your racing and off your peak hp rpm by a few hundred.. Otherwise the difference in mpg vs getting up and go isn't going to be very noticeable, figure at 2000 you'll be at 55 with the 4.10 and 68 at 2500, the 3.92 will be 57 at 2000 and 73 at 2500.

If mpg is your concern be careful with the bigger tire, weight as well as diameter can be hurtful to mileage.