woody90

Hey guys so i'm looking to regear.... I'm at 3" on 31's and want to go to a 4.10. I ultimately wanna get it a little more power but i also drive it on the highway. Will my RPMs be pretty high cruising the highway.. with my 3.55's i'm bout 2000rpms at 70. Thoughts pls?

Tom95YJ

My buddy Josh ran 4:10's and 31's on his last 3 XJ's. His milage was very close to like stock an it felt like driving a stock XJ on 225/75/15's as far as power goes, If you plan on jumping to 33's or larger in the future I would gear deeper to 4.56.

woody90

even 4.10's with 33's wouldn't be to bad. Yes 4.56's are better but it could be done no?

Atmos

you're going to spend $900-$1200 so you can save money on gas?

woody90

and to have a little more power

woody90

you guys think it would be worth it or no?

Boost_Retard

Yes i say its worth it 100%, i lifted my 01 3.5", installed some 31x10.50's, drove it like that with 3.55 for a few months, then re geared to 4.11 and swapped in front and rear true tracs at the same time. the jeep drives better than it did stock. i drive it on a 3 hour high speed highway trip on a regular basis and it pulls great. revs are great. jeep is very happy now with the 4.11s, it did not really enjoy the mountain pass with the 3.55's and 31's..

Im sure if you had no idea what it was like with stock tires and 3.55's you would probably think it was OK with the 31's and 3.55, but it is 100% better with 4.11

you gotta factor in things like more wind resistance, extra vehicle weight, extra rotating weight with the larger tires... all these things make the 4.11 shine.

woody90

that helps i don't plan on goin bigger than 31's and i definitely notice the sluggishness heading up the canyons definitely have to horse on it to maintain speed. I'm aware it gets pricey but i don't mind spending the money to have a more enjoyable ride.

Atmos

you've got an auto trans? I dont think a regear is worth it unless you're gonna do some 33's+ and 4.56 or 4.88
if you want better gas/power run smaller tires or buy a different vehicle.

woody90

whats wrong with a 4.10 on a auto trans

ColoradoCorey

I have a 3.5 on 31s with a manual trans, I think Im gonna jump up to 410s in mine. I have been advised to change my reaer end all together but I think Im gonna stay with the 35 and just buy a locker with the 410s.

Atmos

alright man if you've got the money go ahead. I just don't see the point in regearing for hundreds of dollars to save a little gas and get back up to stock power on 31's

ColoradoCorey

ok so I just did all the calcs on my Jeep (4L I6, AX-15 Manual, NP231, D30&35) with 3.07 gears

FD ratio

1) 11.76
2) 7.15
3) 4.42
4) 3.07
5) 2.43

with 4.10

1) 15.70
2) 9.55
3) 5.90
4) 4.10
5) 3.24

Crawl Speed Feet Per Minute @ 2k RPM on 3.07 and 31s

1) 345
2) 568
3) 918
4) 1322
5) 1674

Crawl Speed Feet Per Minute @ 2k RPM on 3.07 and 75 series

1) 322
2) 529
3) 855
4) 1232
5) 1559

Crawl Speed Feet Per Minute @ 2k RPM on 4.10 and 31s

1) 259
2) 425
3) 688
4) 990
5) 1253

Also speed @ 2k RPMs

31s and 3.07s

1) 16
2) 26
3) 42
4) 60
5) 76

75 series on 3.07

1) 15
2) 24
3) 39
4) 56
5) 71

31s on 4.10

1) 12
2) 19
3) 31
4) 45
5) 57

So,..according to my calculations, On a stock 3.07 running 31s I am gonna be alot faster in the long run (less rpms per mph) however I have less torque or take off power. If I run 4.10 I am gonna have alot more power in the beginning but rap out quick. Running 75 MPH with 4.10 will have RPMs at about 2600+. My power band is between 2500 and 3500 (I believe). I like to run lower RPMs for a couple reasons (Less noise on highway and better fuel economy).

I would like to get a couple of more ideas on what you guys think. Specifically those who have this setup. I really want the low end for crawling but also want the top end for cruising.

P.S. I will not be changing from my stock axles, Just wanna do gears.

Thanks and have a wonderful day.

Boost_Retard

i have an auto trans, IMO regearing is just part of building a vehicle. i regear everything i build to suit what its ment to do. My jeep is running 4.11, the samurai ran 4.11 with 30x9.50 & then later changed to 4.56 to compensate for heavy 31x12.50 boggers, the off road race car now runs 5.38 so i can shoot out of the corners quickly..the turbo drag bug went from 4.10 to a 3.70 so i could build up more load and turn the boost on quicker..you probably want your vehicle to perform....most of the time, that requires a regear.

sure it costs money but why spend cash on lifting a truck and putting nice tires and so on then only to have it be a slug because you cheaped out on gearing?

if you dont have the $$$ right up front, then yeah, lift it up, deal with it..get some cash some day? re gear. it will run and drive no problem on 3.55 with 31's its just WAY better with 4.11.

if you learn to install gears yourself its actually pretty damn cheap to do.

fritzthekatt

x2