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Discussion Starter · #1 ·
I've got a 2001 4.0 automatic. I hear a lot of questions and answers about manuals but very few about autos. What would be the ideal gears for 33s on this setup. I'm not gonna be climbing rocks or anything. Just minor mudding and short rides. I have 3.07 now. This may be just fine, don't really know. Also can someone tell me what I can expect to pay to regear, parts and labor? Thanks for any help
 

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While 4.56 is the usual recommendation for the 4.0L engine and 33" tires when the transmission is the 5-speed manual, your 3-speed automatic will do best with 4.10 gearing which will put the rpms where they need to be for 33" tires.

Typical cost of regearing for both axles, parts and labor is somewhere between $1000 and $1200. I paid slightly less than $1100 for my last regearing.
 

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My wrangler is also an automatic 4.0 with 3.07. I am currently running a 31" tires and man she is sluggish. I took Jerry's advice and re-gearing to a 4.10 ratio with a 33" tires. This is your chance to add lockers or LSD when you get it re-gear. This will save you time and money later if you decide to get them.

I was lucky to find an 05' Rubicon rear dana 44 with 4.10 gear. I am left with the front to get worked on and adding a Detroit Truetrac LSD to it.
 

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Jerry,
I'm wondering the same thing only mine is the 4 speed auto on an 05 LJ w/4.0. I currently have 3.73s. One of the other techs at the shop I work for is really good with setting up diffs and I get the parts at cost. I wont have to pay anything but, parts and maybe a case of beer as we have unlimited use of the shop anytime we want to do something with our own vehicles.
 

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Jerry,
I'm wondering the same thing only mine is the 4 speed auto on an 05 LJ w/4.0. I currently have 3.73s. One of the other techs at the shop I work for is really good with setting up diffs and I get the parts at cost. I wont have to pay anything but, parts and maybe a case of beer as we have unlimited use of the shop anytime we want to do something with our own vehicles.
Wow you have a SMOKING deal going for getting your gears installed. Your 4-speed 42RLE transmission is a totally different beast from the 3-speed 32RH. Its overdrive gear ratio drops the rpms so much that you need an extra-low axle ratio to compensate. For your 4-speed and 33" tires with your 4.0L engine, go right to 4.88 and don't even consider 4.56. :)
 

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Jerry,
I'm wondering the same thing only mine is the 4 speed auto on an 05 LJ w/4.0. I currently have 3.73s. One of the other techs at the shop I work for is really good with setting up diffs and I get the parts at cost. I wont have to pay anything but, parts and maybe a case of beer as we have unlimited use of the shop anytime we want to do something with our own vehicles.
Joshpeb...can I be your friend and I will bring the beers for re-gearing my Jeep?:D:D
 

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Discussion Starter · #7 ·
Thanks, I work for a power company any our mechanic said he could do it, I'm sure for a pretty good price. Any suggestions on a company online for a complete set for front and rear. Also will it come with everything I will need to just hand it to him and say here ya go.
 

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Thanks, I work for a power company any our mechanic said he could do it, I'm sure for a pretty good price. Any suggestions on a company online for a complete set for front and rear. Also will it come with everything I will need to just hand it to him and say here ya go.

Look into Superior axle and gears or OEM. To complete the whole front or rear, you will need the ring and pinion, master install kit, carrier for 4.10 gear ratio, and gear lube.
 

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I have a 04 Rubicon with the 4 speed automatic and 33s. It has the factory 4:11 gears. I would like 4:88s but the 4:11s are good for now. At 50mph I am at about 1700rpms. Good luck.
 

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At 50mph I am at about 1700rpms.
:eek: that's lugging the engine, I'd turn the OD off so the engine will be running more efficiently. Lugging is bad for an engine, it can cause pinging/premature detonation from increased combustion chamber pressure. :)
 

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Jerry Bransford said:
:eek: that's lugging the engine, I'd turn the OD off so the engine will be running more efficiently. Lugging is bad for an engine, it can cause pinging/premature detonation from increased combustion chamber pressure. :)
Jerry, what would you say the optimal Rpm's should be at highway speeds? I have an 04 sport no lift and 31" M/Ts. My speedometer is about 10%off because of the tires so when it's at 60mph I assume I'm doing about 66 and my RPMs are between 1900-2000 usually. Should I be turning my overdrive off at highway speeds? How will it affect my fuel economy? I assume it will increase my power.

Oh yea it's an automatic
4.0 inline 6.
 

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To me Loo, 1900-2000 rpms at 66 mph is, where the TJ is concerned, lugging the engine much of the time... especially if you're running larger than stock size tires. Such rpms are ideal for most cars but they are too low for a Wrangler that has bigger/heavier tires and the aerodynamics of a barn door.

For my 35" tires, 2700 rpms are pretty ideal for me at 70 mph. My present Rubicon is only perhaps 2250 or so at that speeed and it's a frustrating rpm. I bought it with 4.88 gears already installed and with its 4-speed automatic and 35" tires and it really needs 5.13 gearing which is as low as the Rubicon axles can be geared to. 5.38 would be even better.

My last TJ (stolen) originally had a 5-speed with 35" tires and its 4.88 gearing produced 2700-2750 rpms at 70 mph and it was an absolutely ideal rpm. 33" tires could get away with slightly lower rpms and 31" tires could get away with slightly less than that. But 1900-2000 rpms at cruising speeds would only be appropriate in my Toyota or the wife's Lexus... I wouldn't be happy with those rpms in my Wrangler at all. :)
 

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Jerry Bransford said:
To me Loo, 1900-2000 rpms at 66 mph is, where the TJ is concerned, lugging the engine much of the time... especially if you're running larger than stock size tires. Such rpms are ideal for most cars but they are too low for a Wrangler that has bigger/heavier tires and the aerodynamics of a barn door.

For my 35" tires, 2700 rpms are pretty ideal for me at 70 mph. My present Rubicon is only perhaps 2250 or so at that speeed and it's a frustrating rpm. I bought it with 4.88 gears already installed and with its 4-speed automatic and 35" tires and it really needs 5.13 gearing which is as low as the Rubicon axles can be geared to. 5.38 would be even better.

My last TJ (stolen) originally had a 5-speed with 35" tires and its 4.88 gearing produced 2700-2750 rpms at 70 mph and it was an absolutely ideal rpm. 33" tires could get away with slightly lower rpms and 31" tires could get away with slightly less than that. But 1900-2000 rpms at cruising speeds would only be appropriate in my Toyota or the wife's Lexus... I wouldn't be happy with those rpms in my Wrangler at all. :)
So would turning off OD make it a little bit better for now(aside from regearing of course)?
 

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Jerry Bransford said:
Certainly, I turn mine off all the time myself. :)
Do you notice much difference in your fuel economy?
 

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Do you notice much difference in your fuel economy?
If I was super worried about fuel economy, I would be driving a Prius. But since you would only take the Jeep out of Overdrive when the engine was lugging which causes poor fuel economy anyway, taking it out of overdrive probably isn't likely to make it worse at all. It might even help if you're driving up even a slight grade.
 

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Jerry,
I'm wondering the same thing only mine is the 4 speed auto on an 05 LJ w/4.0. I currently have 3.73s. One of the other techs at the shop I work for is really good with setting up diffs and I get the parts at cost. I wont have to pay anything but, parts and maybe a case of beer as we have unlimited use of the shop anytime we want to do something with our own vehicles.
lucky!! ill be your friend too :)
 

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Jerry~
I have a 2000 TJ, automatic with 4.10 gears and running 33x12.5x15 tires. My rpm is at 2900-3000 at 70mpg. Is this an ideal rpm range? I am afraid of running it too high. Thanks
 
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