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What gear ratio should I install in my Jeep Wrangler TJ / LJ? (and other re-gearing FAQs)

Chris

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I wanted to make a thread about recommended gear ratios to help out fellow TJ / LJ owners. My reason for this is because we see this question come up all the time, and it could be helpful for new owners to have a thread like this to reference. Those "gear ratio" charts you see floating around the internet are notoriously inaccurate, especially when you consider that they don't take two of the most important factors into consideration: which engine you have, and which transmission you have. Those factors are absolutely crucial (along with tire size) when making a decision on which gear ratio to go with.


6 Cylinder Engines
Keep in mind that the deepest gear you can put in a non-Rubicon model Jeep is a 5.13, while the deepest gear you can put in a Rubicon model Jeep is a 5.38. This chart only covers up to 35" tires, and the primary reason for this is because with 37" tires or larger, you should no longer be running stock axles at that point, and therefore your gear ratio limitations will change. The table below is laid out by tire size in the left hand column, and transmission on the top row. Match up your transmission with your tire size to determine the appropriate gear ratio.

32RH42RLEAX15NV3550NSG370

30"

3.73

4.56

4.10

4.10

4.10

31"

3.73

4.88

4.56

4.56

4.10

32"

4.10

4.88

4.88

4.88

4.56

33"

4.10

5.13

4.88

4.88

4.56

34"

4.56

5.13
5.38 (Rubicon models)

5.13

5.13

4.88

35"

4.56

5.13
5.38 (Rubicon models)

5.13

5.13

4.88

4-Cylinder Engines
Generally speaking, it's not a good idea to go over 33" tires on the 4-cylinder engines. For off-roading purposes it's fine, but if you plan on doing any highway driving, anything larger than a 33" tire on a 4-cylinder is really going to make life miserable. The table below is laid out by tire size in the left hand column, and transmission on the top row. Match up your transmission with your tire size to determine the appropriate gear ratio.

30RH42RLEAX5NV1500NSG370

30"

4.10

4.56

4.56

4.56

31"

4.10

4.88

4.88

4.88

32"

4.56

4.88

4.88

4.88

33"

4.56

5.13

5.13

5.13

34"

5.38

5.13

5.13

5.13

35"

5.38

5.13

5.13

5.13

Which transmission does my Jeep Wrangler TJ / LJ have?
For information on which transmission you have in your Jeep Wrangler TJ or LJ, please see this post.

Which engine does my Jeep Wrangler TJ / LJ have?
For information on which engine you have in your Jeep Wrangler TJ or LJ, please see this post.

Which axle gear ration did my Jeep Wrangler TJ / LJ come with?
If you need help determining which gear ratio you currently have, see this thread here: How do I determine my axle gear ratio?

What RPM do I want my TJ to be at at highway speeds?
Ideally you want your engine to be above 2000 RPMs on the highway. The 4.0 for instance doesn't really start it's power band until past 2000 RPM, so keeping it under 2000 RPM at highway speeds is detrimental to performance, and it can also be bad on your engine (in terms of carbon build up, poor fuel economy, etc.). Do not listen to anyone who tells you that you should be crusing at highway speeds with your RPMs under 2000 RPM. This is completely inaccurate and bad information. I prefer mine to be around 2300-2500 RPM at 65 mph, which I feel is the sweet spot for both fuel economy and performance.

What's with 5.13 and 5.38 gears?
5.38 gears will not fit in any other axle other than the Dana 44 axles. In many cases, 5.13 is recommended above for 35s, when 5.38 would actually be a better choice. However, unless you have a Rubicon model (that has both a Dana 44 front and rear axle), then you will have no choice but to use 5.13 gears, unless of course you swapped in Rubicon axles. Many of you will have a Dana 44 rear on your Sport, Sahara, or special edition model TJ. The issue with that is that while you could fit 5.38 gears in the rear Dana 44, they will not fit in your front Dana 30 axle. Remember, that front Dana 44 axle ONLY comes on Rubicon models.

Do I need to have matching gear ratios in both front and rear axles?
Yes! Your front and rear gear ratios must match! If not, you will do serious damage to your vehicle (unless of course you never engage 4WD, in which case, technically you'd be fine.

How much does re-gearing typically cost?
I've found that re-gearing typically costs anywhere from $1000-$1600 for the labor. I've had it done twice, and each time paid $1200 for the labor. This of course excludes parts. You should expect to pay around $500-$800 for parts in addition the labor.

Which brand of gears should I go with?
I personally always recommend Revolution gears, as they are very highly regarded and run by many of us. The general rule of thumb though is to go with whatever gears your installer / shop will warranty. Often times shops will not offer a warranty on certain brands of gears they have never installed before. For this reason, if you really want Revolution gears, but the shop will only warranty Yukon gears, the smart thing to do is go with whatever the shop will warranty.

Is there a break-in procedure for new gears?
Yes, there is indeed! Though Revolution has recently started making gears that do not require any break-in period whatsoever. In this case, you want to ask the shop installing the gears what they recommend for break-in procedure, and follow their recommendations to the T. Be very aware that if you do not follow the break-in procedure, there's a very good chance you will damage your gears and have to have them replaced. Those break-in procedures are there for a reason.

Should I attempt to install new gears myself?
Absolutely not. If you are reading this, it means you've likely never done it before, and you shouldn't start with learning to wrench by installing gears. Ask someone like @AndyG what happened when he attempted to install his own gears. This isn't to say you couldn't teach yourself to do it, but if you plan on getting it right the first time having never done a gear install before, you'd better think again! This is one of those tasks that takes a lot of skill and experience, as there are a number of variables that all need to be very accurate.

Is there a gear ratio calculator I can play around with?
Yes, there is indeed! Check out the Grim Jeeper Gear Ratio Calculator. It's a very helpful tool that will allow you to see how a given gear ratio will affect your Jeep.
 
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OP
Chris

Chris

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@Jerry Bransford, @Rob5589, and everyone else.

Care to help me add to this? I admittedly don't know everything, so I look to your guidance to help me complete the rest of these charts.
 

Rob5589

Certified video trained differential rebuilder
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Regarding the 2.5/2.4: Gearing for the 6 spd is the same as the other manual trans. With the 4.46 first gear you can get by with the next taller ratio. I still recommend the lower of the two.

Break in; do whatever the gear manufacturer recommends. If the gear installer has a break in procedure then follow that in order to maintain the warranty.

DIY; I don't recommend it but there will be those that want to tackle the job. If you are able and willing to DIY, go for it. It will save you a ton of cash. Just a quick fyi; if you keep coming back with pic after pic of patterns, backlash numbers, torque values, etc, you should not have tackled it yourself.
 

Ernest.1998

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Mar 25, 2019
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Location
San Diego
If I put the 4.56 in my wrangler and I have 30s and the 4 cylinder AX 5 transmission will this help my top speed increase and give me more power? Also if eventually I was gunna put 31 on my Jeep should I just put 4.88 and will these also help my power and too speed?
 
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Honeybadger

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Mar 14, 2019
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Location
SoCal
If I put the 4.56 in my wrangler and I have 30s and the 4 cylinder AX 5 transmission will this help my top speed increase and give me more power? Also if eventually I was gunna put 31 on my Jeep should I just put 4.88 and will these also help my power and too speed?
I have 4.56 in my 6 cylinder manual w/ 4” lift & 33’s right now and it works well. I think you would be fine with that gearing for 31’s. I do wish I had mine @ 4.88 or 5.13 already because I’m building to 35’s and do a lot of rock crawling.
 

Honeybadger

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What’s it feel like driving a manual on 35’s with 4.88 or 5.13 folks? Wondering about the on road and off road performance. Seems like 5.13 you would never even need 1st gear on pavement unless your starting uphill.
 

JMT

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@Chris, 4.88 seems to low for the 4.0 with NSG370 (6-Speed) and 33’s. My RPMs at 70mph with 4.56 is 2850. I think you’d surpass 3000 with 4.88’s.
 
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Chris

Chris

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@Chris, 4.88 seems to low for the 4.0 with NSG370 (6-Speed) and 33’s. My RPMs at 70mph with 4.56 is 2850. I think you’d surpass 3000 with 4.88’s.
Thanks for pointing this out, I'll change the chart. I've actually been looking for input on the chart, as some of it I wasn't even sure of myself. I did the best I could with guessing, but real world input like this helps a lot. Thanks again!
 

JMT

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Thanks for pointing this out, I'll change the chart. I've actually been looking for input on the chart, as some of it I wasn't even sure of myself. I did the best I could with guessing, but real world input like this helps a lot. Thanks again!
The usual recommendation on the forum is 456 for 33’s with a 4.0 and NSG370 and 488 for 35’s. Sometimes I see 488 recommended for 33’s. I personally think that would be too low and one other user on here who has 488 agrees. The truth is this is the hardest transmission to decide on since the proper ratio falls in between what is available
 
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Pacoson71

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Jan 27, 2019
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Charlton, MA
42RLE can go to 5.89 etc... the 5.38 is RG&A thick cut made to fit the factory locker.
Other brands will fit with different modifications. I few have said, if there were an option for a 5.89 from RG&A, they would have it, with their 35s.
 
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Chris

Chris

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The truth is this is the hardest transmission to decide on since the proper ratio falls in between what is available
Interesting, I didn't know that! In that case, I'd probably opt for the 4.56 gears as well. At 65 mph (which is the speed limit in most places on the highway), I like to be around 2500 rpms give or take.
 

Chief Brohician

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Hmmm, tire size 33”, engine size straight 6, trans 32RH auto, axles Dana 30/44, gear size 4.10. Going with a 2” lift. Should I consider upgrading the 32RH to the 42RLE and put in 5.13 gears? Anything else I am not considering or overthinking?
 
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Chris

Chris

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Hmmm, tire size 33”, engine size straight 6, trans 32RH auto, axles Dana 30/44, gear size 4.10. Going with a 2” lift. Should I consider upgrading the 32RH to the 42RLE and put in 5.13 gears? Anything else I am not considering or overthinking?
No, don’t put in a 42RLE, that would be a downgrade, trust me.

4.10s would work great with your 32RH and 33s.
 
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billiebob

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This is a very specific chart for guys wanting crawl ratios.

Horribly deep gearing for a daily driver.
The only thing accurate about the ratio recommendations is for guys running 35s or bigger or guys running the 4 angry squirrels. The smaller the engine or bigger the tire, the less room there is for compromise.

For the average guy 4.0L running 33s and the 32RE 3 speed automatic with no overdrive, 3.07s are perfect. 2200rpm at 70mph will return reasonable gas mileage and dropping to 2nd gear will give 3300rpm at 70mph, perfect for hills, headwinds and passing.

The only reason to go deeper is lift off the line. Far more important than power band at 70mph is getting started from a stop. With 3.07s off road, or on a forestry road, the range of speed in 4LO, in each gear makes for relaxed driving.... and the ability to do 60mph in 4LO. I'd go into 4LO as soon as I left the pavement with 3.07s. 90% of my wheelin' is mountain trails, forestry roads, old logging roads with the odd foray thru a ditch to reach a beach. I have zero need for ceawl ratios but I do want reasonable mpg.

Gear for the wheeling you do.
 
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