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Recommended gear ratio for 06 LJ with 33s?

2006LJChris

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I have recently bought an 06 LJ auto and put 33s on it with a 4” lift, it seems to be lacking a little power at speed (55-60 has to keep dropping out of overdrive) trying to figure out the best option for regearing leaning towards 4.10 would that get it back to stock? Or should I go lower? Thanks, Chris
 

Drafthorse

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That's what I ended up with after regearing. It was between that and 4.56. Since I wasn't going to go bigger on tires or do much off roading, that's where it landed.
 

derekmac

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If it were a 6 speed, then 4.10 could be useable. I'm no expert (but there are many here), but you'll probably want 4.88's (or even 5.13) for them. Folks like @Jerry Bransford and @Chris will be able to give you a proper recommendation.
 

Steel City 06

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4.10/4.56 would probably only be appropriate for Jeeps with the 6 speed manual. The auto has a much taller OD and generally needs to be geared deeper.

Read through this thread for more information:

Personally I would go with 5.13 gears with the 42RLE and 33s. That would put you at ~2500 RPM at 70 mph. For a comparison, a stock TJ Rubicon with NSG370 will do 2700 RPM at 70 mph in 6th gear.

Going from 3.73 to 4.10 is not going to be a significant difference and in my opinion is not worth the money.
 
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2006LJChris

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4.10/4.56 would probably only be appropriate for Jeeps with the 6 speed manual. The auto has a much taller OD and generally needs to be geared deeper.

Read through this thread for more information:

Personally I would go with 5.13 gears with the 42RLE and 33s. That would put you at ~2500 RPM at 70 mph. For a comparison, a stock TJ Rubicon with NSG370 will do 2700 RPM at 70 mph in 6th gear.

Going from 3.73 to 4.10 is not going to be a significant difference and in my opinion is not worth the money.
Thanks for all the info it helps a lot, do you think 5.13s could handle 35s if I went to them?
 

Mike the Silver TJ

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I have a manual with 33's and 3.73, its fine in my opinion. Test drove an LJR with an auto and 4.10 and that is when I finally understood the need for re-gearing. It definitely needed some help. No way would I spend $1822 to go from 3.73 to 4.10, just not enough change in gearing for that money. $1822 is the quote I got to regear the rubicon I was considering from 4.10 to 4.56 or 4.88.
 

Steel City 06

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Thanks for all the info it helps a lot, do you think 5.13s could handle 35s if I went to them?
5.13 is the deepest you can regear a non-Rubicon TJ without a front axle swap. Rubicon TJs can install 5.38 and 5.89 gears because those gears are available for the D44 axles, but they are not available for the low pinion D30.

5.13 would be acceptable for 35s. Ideally it would be 5.38s, but since 5.38s are not available for the Dana 30 5.13s for 35s will be the best you can get, and will do much better than your current 3.73 gears and 33” tires.

So yes if you plan to install 35s definitely go to 5.13
 

DWR

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I have a manual with 33's and 3.73, its fine in my opinion. Test drove an LJR with an auto and 4.10 and that is when I finally understood the need for re-gearing. It definitely needed some help. No way would I spend $1822 to go from 3.73 to 4.10, just not enough change in gearing for that money. $1822 is the quote I got to regear the rubicon I was considering from 4.10 to 4.56 or 4.88.
IDK how you’re ok with 33” and 3.73... I have 4.10 and 33” tires and can’t stand it (though my engine is kinda tired/ worn out)... but I also daily a 455hp camaro so I’m kinda used to having plenty of power.
 
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Chris

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Thanks for all the info it helps a lot, do you think 5.13s could handle 35s if I went to them?
5.13s is what you want for 35s. Ideally you want 5.38, but those won't work unless you have a Rubicon model with the D44 front and rear axles.

So 5.13 will be as deep as you can go, but that should be good for 35s.
 

jjvw

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Which by extension, suggests that 33s should have 5.13.

Run the numbers on Grimmjeeper.com to see for yourself.
 

LukesfirstJeep

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I have 32" tires on my LJ, non Rubicon, and the 42RLE transmission. I went 4.88. It was a big improvement, but I frequently turn the OD off if I'm on back road and don't plan on speeds over 55 MPH. With 33 or future plans for 35, I'd go deeper than 4.88.

FWIW, I found a local 4x4 mechanic that charged $250/axle for the installation. All in, I was about $1000.
 
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2006LJChris

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Awesome, thanks for all the information helps a lot, looks like I’m gonna go with 5.13s. Another question , do you think 35s would be pushing it for stock axles?
 

Rob5589

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Awesome, thanks for all the information helps a lot, looks like I’m gonna go with 5.13s. Another question , do you think 35s would be pushing it for stock axles?
Yes and no. Hard core wheelin, I'd look into some stronger axles. Other than that, throw some 5-760x u joints in the front axles and rock on. If you break something, upgrade as needed.
 

Steel City 06

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Ok, what would the weak points in the steering be? Would you just upgrade as needed? If/when something breaks
Here is an incomplete list of the things you will likely need for 35s:
  • 5.13 or deeper gears
  • Chromoly front/rear axle shafts
  • 4” SL and 1” BL or highline (or possibly metalcloak style) fenders
  • Effective backspacing of ~3.75” on 15x8, 16x8, or 17x8 wheels
  • New rear driveshaft to correct angle caused by lift
  • Heavy duty spare tire carrier, if you carry a spare
  • Big brake kit, if you live anywhere with hills
  • Heavy duty steering kit (tie rod, drag link)
  • Adjustable control arms and track bars (to accommodate lift)
  • Longer shocks
  • Longer bumpstop extensions
So it’s definitely feasible, and you’ll probably already want to install some of these items for 33s, but there is some additional work.

37s and up generally require different axles, but some people who don’t do anything extreme can get away with 37s on stock axles.