What's in your rear?

[KyleTay]

Well your rear differential is what I'm wondering about.

I have 31" tires and 3.55 open diff right now... I am moving to a 3.73 LSD, but wondered if I should jump to a 4.10 LSD instead?

Your thoughts are considered relevant until proven otherwise, or visaversa I always mix that up

 

[Sasquatch_Ryda]

The FX4 rangers ran 31" tires and came with 4.10's from the factory. Most definitely go 4.10 if you are re-gearing.

 

[disciplerocks]

If you are going to re gear then 4.10s are easy enough to come by. 3.73s work well with my 2.9 and 30s. I know others that push 33s with 3.73s, but thats with a 4.0.

 

[alaskan155]

i run 3.55 with 35 inch tires but even with a 5.4 the 35s slowed it down quite a bit so i would say 4.10 or 4.56(that's what i want eventually)
when im offroad i put it in low ranger to be nice to my 4r70w(AOD).

so with a 4.0 and 33s i would want at least 4.10, not to mention you will see more gain going from 3.55 to 4.10 than 3.73(be hardly noticeable)

if you plan on going bigger maybe look into 4.56s but if staying 33s 4.10 should be good

if you have a manual tranny then 3.73 would be fine

 

[-Nathan-]

I run 4.56's with 33's and its perfect with my 4.0. I dont know why people are so afraid to gear their rigs. Run at least 4.10's with your 31's. 4.56's if you ever plan on 33's.

 

[bcost882]

with the 4.0L 3.73 would be ok but if you go to bigger tires you will definatly need better gears. it is easy to find 3.73 explorer diffs but 4.10s are a bit harder to come by. so it will mostly what you can find.....if you just wanna do gears in the diff you have then go for it. anything will be better than 3.55s and 31s haha

 

[canyoncritter]

4.56's if its a 4 banger

410's if its a v-6 and 4x4 if its 2wd and you have the 8.8, 4.30's

 

[KyleTay]

Thanks for the input everyone. Sounds like a 4.10 will be in there soon.

 

[GMillion$]

how much will you be dd'ing it? and is it std or auto?
on my dailydriver, I'm running 32's with 3.73's (4.0l, std) and i almost wish it was geared higher for when i'm cruisin to work @ 140kph (90mph?) for 1/2 hour. when i offroad it, i just dump into lowrange anyway and chug along great in 2nd gear.

 

[KyleTay]

90% dd... 2wd, auto...

I cruise at 65 mph and 2000 rpms... its like the engine is not even on its a quiet ride. But I am in Oklahoma where it is allllll flat land... I will be moving back to Georgia in the hills in a couple weeks... I thnkk the 3.55 will be too tall

 

[disciplerocks]

I just upgraded to 32s and not having a problem with 3.73s.

 

[strvger]

4.56 with a detroit locker, and i'm running 31 inch tires. great combination for me and i'm 95%dd and 5% light trails.

 

[59bisquik]

My B2 came stock with 4.10's. When I upgraded to 32's, the calculator in the tech section said to return to normal I would need something in the 4.80 range. I swapped in 4.88's and really liked it. It felt just like stock but with a 3" lift and 32's. Now I am running the same 4.88's and 35's. They were great with 32's, but now with 35's, I should of bought 5.13's.

 

[JimJa1943]

I live in the mountains (7,500'). I moved from the OEM 4.10 L/S to 3.73 L/S because most of my MILES are freeway. Although fine for freeway driving the 3.73s were not suitable for the bulk of my driving TIME since most of that time is spent on secondary roads. After one year I went back to a 4.10 open with a electric locker. It's perfect for here although I slow down a little on the freeways as the RPM approaches 2,800-2900 at 75-80. As you would expect MPG has suffered about 2 MPG with the 4.10s on the freeway, but is about the same at 60-65 MPH which I normally drive day to day - 21 or so.

That is with a 5-speed manual. If I had an automatic, I would have stayed with the 3.73s. The 3.73s are better suited for the automatic. I've got standard 2.55 x 16 tires.

 

[KyleTay]

Interesting additions to this discussion.

I determined that my mpg suffered on my long trips. I have driven 2000 miles since the start of this thread. Made two long highway trips.

The first one I had my old school aluminum camper top on and my tools... has a ladder rack... and I traveled 80 mph. Got 17 mpg

The second trip I unloaded everythjing and removed the camper. I drove a steady 75 mph and got 22 mpg.

With 235/75r15, the stock tires, and the camper shell I was getting 26 mpg at 65 mph over long distance.

With the 31/1050r15 ATs and no camper shell I get 22... this is using the GPS for miles traveled as my odometer is now 3.8% slow.

I had my truck serviced today; new plugs, wires, oil change, air filter and fuel filter. Next week I will be driving in town mostly, but Friday I head home to Georgia. This will give me another good LONG drive to test fuel economy with the camper and about 1000 lbs in the bed.