brendancfarrell

I'm gonna end up build up a set of axles for my 99. I've got a 30/8.25 and I think I'm gonna end up building the same set. I don't do too much wheeling due to work, but when I do, it's mainly trail riding with mud. I'd like to run chromos, lockers and new gears, either 4.10s or 4.56s. That's my question. I do daily this Jeep. I've been told that 4.10s are better for highway. But will 4.56s be a better investment if I plan on going with a bigger tire later? Now, I'm talking a 35 nothing bigger than that. A 60/60 swap is planned for the 38.5s.

So to break that down:
4.10s or 4.56s for a DD with 33s.

Red82

Either will serve you well, but I think you'd be really happy with the 4.56s unless you run the highway a lot.

brendancfarrell

That's the thing. To wheel, I need to drive 45 minutes to an hour to my property, which is down the highway

Red82

That's nothing you'll be fine.

Atmos

I really liked my 4.56/auto trans/33's. I think the stock drivetrain/axles are perfect for geared/locked 33's + street driving and I wish I could keep it at that tire size. loved it on the streets. the jeep feels a little doggish on the 35's now

get the 4.56's you wont regret it

dav5942

Don't do mud but stock 3.55s are fine with 33s for crawlin and dd with 30/8.25s.

TheCK4x4

dd yeah crawling not so much , 456s prob your best bet

brendancfarrell

With my 3.55s, I can barely stay at highway speeds without sitting at 3k rpms. I'm also quite tired of the 9 city and 12 highway mpg's. I'm not expecting 20's but teens would be nice. Also, my rear spiders are gone and the front is also making a nice sound. It's about to upgrade

brendancfarrell

So I'm assuming that 4.56s are the way to go? How bad will they be on the highway though. Like on a 2-3hour drive?

Atmos

it's really not that bad. the difference between 4.10 and 4.56 is like 200 rpm at speed. you'll be very glad you went deeper mine handled freeways like a champ. I view gears as a performance upgrade so I never calculated on 33's. but for my latest 150 mile trip, loaded down with heavy spare parts and camping gear and no doors on 35's I scored 17mpg. and that's going through the mountains. I'm sure you can do better than that

it was a total dog weighed down for that trip. one ratio deeper is definitely smarter in your case. regardless of slight difference in fuel economy

brendancfarrell

That's what I figured. I always said I would go 4.56s, but I was always told that it would be a tot Dog on the highway haha

Atmos

not at all. I'm ashamed to say I've done better than 90mph on the freeway with that setup

Tamadrummer

I have the same stock set up, so 4.56's will be better than 4.10's on an hour drive going 75mph?

Atmos

you will have to come to your own conclusions. I don't fully know what the engine like as far as RPM vs speed. play around with some gear ratio calculators

http://www.novak-adapt.com/knowledge/gearing.htm

http://www.grimmjeeper.com/gears.html


just to give you an idea. stock auto jeep does about 2000 RPM @ 65mph and 2315 RPM @ 75 MPH

4.56/auto/33's:
2250 RPM @ 65 RPM
2612 RPM @ 75 RPM


4.10's/auto/33's:
2035 RPM @ 65 MPH
2348 RPM @ 75 MPH

or so says the calculator. so whatever that translates to you in economy, take it as you will

Tamadrummer

Will 4.56's be a huge difference in performance from 4.10's on the trails? Say mud and some rocks