What is the largest gear set that will fit in the stock diffs? I need all the mechanical advantage i can get to help out my under powered 4 banger.

 

Well most 4 bangers came with 4.10 gears, not much you can do about it if thats not good enuff for you, then the only way to go is sell it and buy a ruby. Changing the gears to something lower isn't going to give you more power, its a 4 and its going to stay a 4 even if u put 8.8's in it.

 

Are you asking for gears for torque or for fuel economy?
The higher the number (4.88) you get more torque, the lower (3.55) fuel economy. But either way you won't ever be a speed demon with the 4 banger.

 

hey 04wjguy....does that mean i can install 4.88's in the stock housings. that would be a step in the right direction... what's the best name in limited slips for my diffs?

 

thanks for the input mr white. i don't agree, it will take less torque to rotate the 31" tires with a higher mechanical advantage. i would be able to get up to speed a little quicker too!

 

If you have a D35 (I assumed) then the 4.88's are the max size.
You won't be getting up to speed faster with these. Your gaining low end torque but sacrificing speed, if you go the other way you get speed but sacrifice torque.
Your engine has a set amout of HP and torque so you need to find a gear set that will give you a good balance of power and torque with low end pulling power for offroading.

Think of the problem as a weight, fulcrum and lever.
The Jeep is the weight you want to move, the fulcrum is the gear ratio, the motor is the lever your using to move the Jeep.

By changing the ratio all your doing is making the fulcrum larger (harder to move)or smaller (no signifigant movement), you need to change and match 2 of the parts to change the ease of moving the Jeep.

 

First, if you have 4.10's then your ok to get some aftermarket 4.88's they will fit.
Second, they will indeed give you the feeling of more power as it will give you the Torque advantage.
Third, your most likely to get better mileage with them on your 31's as it will allow the vehicle to get to and maintain speed easier.

I can tell you from experience that gearing is everything when it comes to off roading. Power is great for stuff like deep mud, but when it comes to control it is almost always useless. Gearing allows control and still allows you to use the lower powered more fuel efficient engines to get through things. I am not trying to be an ***, but you can ask anyone I wheel with, my truck has all of about 70HP and it gets through more crap than a lot of other high power trucks. My suggestion is if you are going to stay with the 4CYL, then you really should look at gears and a traction adder like a LSD or a selectable locker. When I ran my Cherokee, I used a Lockright in the front with a PosiLoc and then added an LSD in the rear. Even on 31's that truck would do a lot.

 

My point exactly, HP has nothing to do with the problem, just matching the available torque from the engine to the axles.

 

now you guys are speaking my language. i like the 4.88's with a rear lsd. it will bring up my rpm and help spin the larger tires with less effort. thanks for the info lostsoul!
where or in what will i find the 4.88's.... i should get a winch ;)

 

Gears will be new aftermarket, I suggest checking replacing any seals and bearings at the same time. I also suggest the winch idea, mine will be coming out with two next season LOL!