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

Steel City 06 said:
... The recommemded gearing for the 42RLE is actually below that 3000 RPM target at most freeway speeds.
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What speed, specifically? The big reason the 42 might not reach 3k/75rpm is because most are limited to 5.13 and even 5.38 on the Rubicon is not quite enough for 35s. That does not mean the lower rpm is ideal or recommended. It just is what it is.
 
jjvw said:
What speed, specifically? The big reason the 42 might not reach 3k/75rpm is because most are limited to 5.13 and even 5.38 on the Rubicon is not quite enough for 35s. That does not mean the lower rpm is ideal or recommended. It just is what it is.
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I'm assuming 3k at 75 as well.

But even at smaller tire sizes, the chart doesn't recommend ratios that reach that magic 3k/75. Otherwise we would be recommending 5.13 for 31 inch tires and the 42RLE.

If we did recommend a gear based on that target, the 42RLE would be 5.13 for everything 31" and larger for a non-Rubicon, 5.38 for 33s on a Rubicon, and 5.89 for 35s on a Rubicon (with a spacer ring or new carriers).

Interestingly, that would also dictate 7.17s for 40s, assuming you have D60s.
 
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Steel City 06 said:
I'm assuming 3k at 75 as well.

But even at smaller tire sizes, the chart doesn't recommend ratios that reach that magic 3k/75. Otherwise we would be recommending 5.13 for 31 inch tires and the 42RLE.

If we did recommend a gear based on that target, the 42RLE would be 5.13 for everything 31" and larger for a non-Rubicon, 5.38 for 33s on a Rubicon, and 5.89 for 35s on a Rubicon (with a spacer ring or new carriers).
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You're seeing the problem with the inability to gear that transmission properly and the confused thinking surrounding it. Because of that, we get odd recommendations that don't match up with all the other transmissions where we can suggest incremental steps based on tire size that do make sense.

Understanding that TJs with the 42 were undergeared directly from the factory helps to show the problem.
 
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Lunch Patterson said:
I plan on getting 33's some day. The reason I'm was planning on sticking with 31s was so I could get a feel for the jeep and figure out what mods I feel I need, for the type of wheeling/driving I do. This chart scared me like 31s would be almost undriveable somehow. Then I realized the chart says 29s should be undrivable too if you fill in the blank. I will regear for the 33's when I decide to drop the 5-6k to do the suspension, gears, tires, and stuff right.
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I'm running 32" tires (actually 31.5") in western NC mountains. It needs lower gears for sure but for most of my driving it's fine. Driving I-26 from SC to NC that climbs about 1000' in a few miles is irritating as hell but most places are fine.
 
So with the 42RLE in my 06 (non rubicon) and running 35's would it be best to go with 4.88 or 5.13. I mainly just cruze on the streets with occasional back roads and trails.

Thanks!
 
Tristar_tj said:
So with the 42RLE in my 06 (non rubicon) and running 35's would it be best to go with 4.88 or 5.13. I mainly just cruze on the streets with occasional back roads and trails.

Thanks!
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Definitely 5.13. 5.38 would be ideal but that's not feasible without an axle swap.

5.13 would give you adequate torque at freeway speeds and give you good acceleration in lower gears without affecting fuel economy
 
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Michelobe said:
I'm running 32" tires (actually 31.5") in western NC mountains. It needs lower gears for sure but for most of my driving it's fine. Driving I-26 from SC to NC that climbs about 1000' in a few miles is irritating as hell but most places are fine.
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Thanks, sounds like I should be fine. I think I'll just grab 31's and learn as I go! It might be a quick upgrade to 33's and regear if it is bad, haha.
 
billiebob said:
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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ok so I have a 99 TJ 5 speed manual w/ 35’s , Dana 44 front and rear (upgrade) with 4.45 gears... rarely use 1st gear on pavement unless starting on a slight or more grade. 50mph I’m running 3000rpm in 4th gear and 70mph I’m running 3000rpm in 5th gear... with little pull going up hills.... have to go faster down the hill to lose the momentum going up the hill.

off road does great! I usually can tackle almost anything with a little throttle in 3rd low or anything with no throttle in 1st low
 
Reidminer said:
That’s actually a super helpful chart on that site. I am in the process of buying a Tj on trussed Dana 44’s running 4.88’s and was wondering if that was the optimal gear ratio, seems to be a toss up between 4.88 and 5.13’s.
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That chart doesn’t take into account transmission which is a really big deal....
 
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Reidminer said:
That’s actually a super helpful chart on that site. I am in the process of buying a Tj on trussed Dana 44’s running 4.88’s and was wondering if that was the optimal gear ratio, seems to be a toss up between 4.88 and 5.13’s.
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If that TJ is an auto on 35s you want at least 5.38. Maybe even 5.89 if it has aftermarket lockers
 
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Reidminer said:
That’s actually a super helpful chart on that site. I am in the process of buying a Tj on trussed Dana 44’s running 4.88’s and was wondering if that was the optimal gear ratio, seems to be a toss up between 4.88 and 5.13’s.
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@BuildBreakRepeat and @Steel City 06 are right. When I posted that I hadn't thought about the differences with the auto trans Jeeps simply because I'd never owned one, and I was fairly ignorant of a better source to figure our what gearing is optimal. That being said "optimal" is truly a personal perspective and determined more by what you want your jeep to be able to do. If it's a strictly off road rig then lower gears may be more warranted than if you want to be able to cruise down the interstate. I believe someone posted the link to Grimmjeeper?? later on in the thread. It's a MUCH better tool to use when making a decision on gearing.

Here's the link.

http://www.grimmjeeper.com/gears.html
 
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reddvltj said:
@BuildBreakRepeat and @Steel City 06 are right. When I posted that I hadn't thought about the differences with the auto trans Jeeps simply because I'd never owned one, and I was fairly ignorant of a better source to figure our what gearing is optimal. That being said "optimal" is truly a personal perspective and determined more by what you want your jeep to be able to do. If it's a strictly off road rig then lower gears may be warranted that if you want to be able to cruise down the interstate. I believe someone posted the link to Grimjeeper?? later on in the thread. It's a MUCH better tool to use when making a decision on gearing
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Understandable - the auto’s 0.69 overdrive is insane and the wrong gear for our jeeps, makes regearing really fun 🤣 (me on 5.38)
 
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Chris said:
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 / 3.73

31"
3.73
4.88
4.10
4.10
4.10

32"
4.10
4.88
4.46
4.56
4.56 / 4.10

33"
4.10
5.13
4.56
4.56
4.56

34"
4.56
5.13
5.38 (Rubicon models)
5.13
5.13
4.88 / 4.56

35"
4.56
5.13
5.38 (Rubicon models)
5.13
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
4.56
4.56

32"
4.56
4.88
4.56
4.56

33"
4.56
5.13		4.884.88

34"
5.13
5.13
5.13
5.13

35"
5.13
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 REM finished 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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Dumb question, I've heard that the power band doesn't really become optimal until like 2,500, but when I get near that level it sounds like I'm at redline and doesn't sound like I should drive with it that high. Am I just not used to how it sounds yet or is there something wrong with my jeep? The engine just sounds like its maxing itself out but I wouldn't think that would happen until a higher rpm
 
Cheetokps said:
Dumb question, I've heard that the power band doesn't really become optimal until like 2,500, but when I get near that level it sounds like I'm at redline and doesn't sound like I should drive with it that high. Am I just not used to how it sounds yet or is there something wrong with my jeep? The engine just sounds like its maxing itself out but I wouldn't think that would happen until a higher rpm
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Where is the red line on yours? Mine is above 5k rpm.
 
Cheetokps said:
Dumb question, I've heard that the power band doesn't really become optimal until like 2,500, but when I get near that level it sounds like I'm at redline and doesn't sound like I should drive with it that high. Am I just not used to how it sounds yet or is there something wrong with my jeep? The engine just sounds like its maxing itself out but I wouldn't think that would happen until a higher rpm
Click to expand...

I bounce mine off the rev limiter regularly. There’s a reason that a rev limiter exists and it is where it is. 2500 isn’t even coming close to stressing your engine out. Ignore the noise and rev the piss out of it. Driving it at low RPM all the time is actually bad for the engine over time.
 
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