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

[Uncaged]

From the factory bone stock, the 01 TJ with the 32RH runs 68mph at 3000 rpm.

@mrblaine , this statement may require a little more explanation for those of us with less knowledge about TJs. I realize you may have been a little upset when you posted it and left off some details but my stock 02 Sahara didn't break 2500 rpm at 70. It came with the 4.0, 32RH and 3.07 gearing. I am now running 31" tires lowering the rpms. I agree that it is over geared with the 3.07 gearing and I am working on that.

Most of my driving is at around 60 mph and around 2000 rpm now that I have 31" tires. However, using the gearing calculator, 3.07 gears, and the smaller tire sold on TJs in '02 I still do not see 3000 rpm; maybe with 3.73 but my understanding is that they were optional with the 4.0 (again, possible lack of knowledge on my part). It seems to my limited knowledge that Jeep engineers were aiming for 2600 rpm at 70 mph. If I ran 3.55 gears with my 31" tires I should be around 2800 rpm at 70 while the recommended 3.73s put me over 2900 rpm at 70.

Looking at the calculators, along with primarily highway driving and mild off-roading (sandy forest roads in Florida) have me looking at the 3.55s over 3.73s. Maybe I am entering something wrong into the gearing calculator and it is a good thing that we have time to correct this before I have the gears changed.

 

[mrblaine]

@mrblaine , this statement may require a little more explanation for those of us with less knowledge about TJs. I realize you may have been a little upset when you posted it and left off some details but my stock 02 Sahara didn't break 2500 rpm at 70. It came with the 4.0, 32RH and 3.07 gearing. I am now running 31" tires lowering the rpms. I agree that it is over geared with the 3.07 gearing and I am working on that.

Most of my driving is at around 60 mph and around 2000 rpm now that I have 31" tires. However, using the gearing calculator, 3.07 gears, and the smaller tire sold on TJs in '02 I still do not see 3000 rpm; maybe with 3.73 but my understanding is that they were optional with the 4.0 (again, possible lack of knowledge on my part). It seems to my limited knowledge that Jeep engineers were aiming for 2600 rpm at 70 mph. If I ran 3.55 gears with my 31" tires I should be around 2800 rpm at 70 while the recommended 3.73s put me over 2900 rpm at 70.

Looking at the calculators, along with primarily highway driving and mild off-roading (sandy forest roads in Florida) have me looking at the 3.55s over 3.73s. Maybe I am entering something wrong into the gearing calculator and it is a good thing that we have time to correct this before I have the gears changed.

The vast majority of TJ's with the rear Dana 44 got 3.73 gearing up until 03 when the Rubi came out. After 03, I don't know of but two gear ratios for all models with the 4.0 which is 3.73 and 4.10.

Maybe folks with 4 bangers and Dana 35 can chime in but I don't work on those much.

 

[Uncaged]

The vast majority of TJ's with the rear Dana 44 got 3.73 gearing up until 03 when the Rubi came out. After 03, I don't know of but two gear ratios for all models with the 4.0 which is 3.73 and 4.10.

Maybe folks with 4 bangers and Dana 35 can chime in but I don't work on those much.

@mrblaine , thank you for the quick reply. My 02 with 4.0/32RH also has the Dana 35 and 3.07s. The assumption I have been working with was that the engineers arrived at the 3.07s for the smaller tires and highway driving and then offered the 3.73s as an option for the off-road oriented drivers. This put me looking just above 2600 rpm at 70 as my target (to push slightly bigger tires) thus landing at 3.55 instead of 3.73. If my off road use was a little more demanding I would easily go with the 3.73s. However, there is only about 140 rpm difference between the two ratios at 70, so it may not be a big deal.

 

[machoheadgames]

@mrblaine , thank you for the quick reply. My 02 with 4.0/32RH also has the Dana 35 and 3.07s. The assumption I have been working with was that the engineers arrived at the 3.07s for the smaller tires and highway driving and then offered the 3.73s as an option for the off-road oriented drivers. This put me looking just above 2600 rpm at 70 as my target (to push slightly bigger tires) thus landing at 3.55 instead of 3.73. If my off road use was a little more demanding I would easily go with the 3.73s. However, there is only about 140 rpm difference between the two ratios at 70, so it may not be a big deal.

From my relatively limited searching, using auto trader and the chrysler VIN build sheet generator, many of the 32RHs came stock with Dana 30/Dana 35, 3.07 ratio. There are some out there with Dana 30/Dana 35, 3.73 ratio, which I am guessing was an option for those who simply wanted the ratio. Then of course there are plenty of them out there with the Dana 44, which automatically got the lower ratio (3.55 in 1997, 3.73 98-02).

Looking at these build sheets also, I'm noticing that the 3.07 Jeeps came with 225/75R15 which is a 28" tire. I believe the 3.73 Jeeps came with 30's typically but 28-29" might have been in there at some point too, not sure.

So yes, you could use the logic of either ratio to aid you in your regear selection, but no doubt the 3.07 Jeeps felt far more sluggish with only 3 speeds and 3.07 axle ratio. Maybe semi decent on the highway but acceleration surely suffers, at least compared to the others. If I were regearing my Jeep, I'd say following the factory 3.73 setup would be more ideal. Better for offroad, and still good enough to hit the highway, even at the higher rpm.

31's and 3.73 would be a good combo. I feel that 3.55 would be a mistake, not enough change for the money.

 

[Gilly11277]

What would you all suggest I get for 32" tires? I spend 99% of my driving on pavement. My 05 TJ Rocky Mountain Edition has a Dana 44 in the rear and a 30 in front. Gearing is 3.73 according to my Mopar garage specs.

Jeep goes into OD at inopportune times. Haven't really paid much attention to RPMs at 60mph (probably should) but I can tell you for a fact that the Jeep doesn't feel so neutered when I'm closer to 70mph. Turning O/D off is a workaround but I'd rather have RPMs be a little higher because of all the vibrations due to no torque.

 

[machoheadgames]

What would you all suggest I get for 32" tires? I spend 99% of my driving on pavement. My 05 TJ Rocky Mountain Edition has a Dana 44 in the rear and a 30 in front. Gearing is 3.73 according to my Mopar garage specs.

Jeep goes into OD at inopportune times. Haven't really paid much attention to RPMs at 60mph (probably should) but I can tell you for a fact that the Jeep doesn't feel so neutered when I'm closer to 70mph. Turning O/D off is a workaround but I'd rather have RPMs be a little higher because of all the vibrations due to no torque.

I'd personally go straight to 5.13. 32's usually end up real world around 30.5-31" tall. That is roughly 2850 at 75 and 2600 at 70. Hell, many people prefer lower than that still, but you can't go lower than that. I wouldn't go any less than 5.13 personally.

 

[ManWithJeep]

Any reason behind the suggestions of AX15 33s being 4.56 and NV3550 33s not being 4.56 (shows 4.88 suggested for NV3550 with 33s)

NV3550 has a steeper first gear at 4.01, AX15 is 3.81.

5th for NV3550 is .78 and 5th for AX15 is .79.

At 65mph with 33s and 4.56 this is a 30rpm difference. I'm probably missing something if someone could chime in

 

[machoheadgames]

Any reason behind the suggestions of AX15 33s being 4.56 and NV3550 33s not being 4.56 (shows 4.88 suggested for NV3550 with 33s)

NV3550 has a steeper first gear at 4.01, AX15 is 3.81.

5th for NV3550 is .78 and 5th for AX15 is .79.

At 65mph with 33s and 4.56 this is a 30rpm difference. I'm probably missing something if someone could chime in

View attachment 293294

They should have been the same. Likely a mistake that hasn’t been pointed out all this time. They are virtually the same transmission ratio-wise in the real world.

 

[ManWithJeep]

They should have been the same. Likely a mistake that hasn’t been pointed out all this time. They are virtually the same transmission ratio-wise in the real world.

Thanks, wanted to make sure I wasn't missing anything as I will be regearing for 33s

 

[machoheadgames]

Thanks, wanted to make sure I wasn't missing anything as I will be regearing for 33s

No problem at all. I would recommend 4.88 vs the 4.56 since I didn’t clarify which one they should both be recommended to regear to. Many folks are really happy with that combo, especially after trying others.

 

[jjvw]

Any reason behind the suggestions of AX15 33s being 4.56 and NV3550 33s not being 4.56 (shows 4.88 suggested for NV3550 with 33s)

NV3550 has a steeper first gear at 4.01, AX15 is 3.81.

5th for NV3550 is .78 and 5th for AX15 is .79.

At 65mph with 33s and 4.56 this is a 30rpm difference. I'm probably missing something if someone could chime in

View attachment 293294

The ax-15 and nv3550 should be treated the same, as far as I'm concerned.

 

[thedustyboot]

I have a 4 popper with 33s and 4.88s. Im happy with it

two pages deep into this thread and 4.88's are looking like the winning option over the 5.13's. I'm running 33's with stock (4.10) gears and it's not low enough. 4.88 gears seem to be more readily available compared to 5.13's.

I think my biggest stipulation with which ratio I upgrade to is my ability to drive up the 8%-15% grade logging roads at a reasonable speed and trails in 1st gear without the need to engage low range.

Unlike most of the individuals who have posted on this thread my highway driving never exceeds 50MPH and most of the on-road driving is at 35MPH

@Oldguy how long have you been running your 4.88 setup? Where conditions allow, has 1st gear hi-range been adequate for cruising most trails at a comfortable pace? Secondly, forestry roads while driving uphill. I have a handful of roads around my area where 25-30mph is a comfortable speed for the hill but that means close to 3000 rpm in 2nd, whereas 3rd I'd be around 2000rpm but too much tire and not enough motor doesn't make that an option

Sorry for the novel here but I'd appreciate your experience and input before dropping cash on the project.

Kind regards

 

[Francesco.com]

I regeared to 4.56 few months ago coming from 3.07 and 33s 4.0L 5 speed manual. Everything it’s ok and it’s a huge improvement, but sometimes I wish I have chosen the 4.88. In any case 4.56 is short enough to allow me to drive off-road in 4H almost all the time.

 

[machoheadgames]

two pages deep into this thread and 4.88's are looking like the winning option over the 5.13's. I'm running 33's with stock (4.10) gears and it's not low enough. 4.88 gears seem to be more readily available compared to 5.13's.

I think my biggest stipulation with which ratio I upgrade to is my ability to drive up the 8%-15% grade logging roads at a reasonable speed and trails in 1st gear without the need to engage low range.

Unlike most of the individuals who have posted on this thread my highway driving never exceeds 50MPH and most of the on-road driving is at 35MPH

@Oldguy how long have you been running your 4.88 setup? Where conditions allow, has 1st gear hi-range been adequate for cruising most trails at a comfortable pace? Secondly, forestry roads while driving uphill. I have a handful of roads around my area where 25-30mph is a comfortable speed for the hill but that means close to 3000 rpm in 2nd, whereas 3rd I'd be around 2000rpm but too much tire and not enough motor doesn't make that an option

Sorry for the novel here but I'd appreciate your experience and input before dropping cash on the project.

Kind regards

I’d go 5.13. The 2.5 needs all the help it can get. 4.88 doesn’t really even get you back to stock 4.10/27’s. 5.13 makes up for it and gives a bit more pep than stock.

 

[thedustyboot]

I’d go 5.13. The 2.5 needs all the help it can get. 4.88 doesn’t really even get you back to stock 4.10/27’s. 5.13 makes up for it and gives a bit more pep than stock.

Then 5.13 it shall be. I've looked on Revolution's website for the 5.13 flavour but they've been "out of stock" for months now. I guess a guy could go with Yukon but Revolution has a better price and has been well liked by other members of the forum. I've emailed RVG&A but haven't heard anything back yet.

 

[Tiros]

Having read a lot here the recommendation seems to be 3k RPM @75 MPH. A lot of the info for gearing manuals is regarding the 5 speed. My TJ has a .84 overdrive NSG370 close ratio 6 SPEED, 4.0 and 33" tires. So are the recommended gear/rpm combinations in gear 5 @ 1:1, or Gear #6 @.84:1? Currently running a 3.07. One formula 33/30*3.07 = 3.37. So if factory was 30inch tires and I went to 33, that is 110% larger so 3.37 would be the actual ratio required to restore the rpm/gear to factory design? That does not seem right. I must be missing something.
Trying to decide on using 4:10 (LEFT) or 4:56 (RIGHT) I used 33" for my tire size in reaper, which I am now aware might actually be slightly smaller.
I don't crawl. Looking for best drivability and economy IE: A daily driver. Thanks for any and all advice!

 

[jjvw]

Having read a lot here the recommendation seems to be 3k RPM @75 MPH. A lot of the info for gearing manuals is regarding the 5 speed. My TJ has a .84 overdrive NSG370 close ratio 6 SPEED, 4.0 and 33" tires. So are the recommended gear/rpm combinations in gear 5 @ 1:1, or Gear #6 @.84:1? Currently running a 3.07. One formula 33/30*3.07 = 3.37. So if factory was 30inch tires and I went to 33, that is 110% larger so 3.37 would be the actual ratio required to restore the rpm/gear to factory design? That does not seem right. I must be missing something.
Trying to decide on using 4:10 (LEFT) or 4:56 (RIGHT) I used 33" for my tire size in reaper, which I am now aware might actually be slightly smaller.
I don't crawl. Looking for best drivability and economy IE: A daily driver. Thanks for any and all advice!


View attachment 330670

You are over-complicating it. Regardless of the transmission, look at the final drive gear- the last gear you can shift into. That is your highway gear. Anything else up to that, you will naturally adapt to.

Also, in all these gear ratio threads you should have noticed that your tire size for the purposes of the calculators is your center hub height x2. It isn't 33 inches.

 

[Steel City 06]

Having read a lot here the recommendation seems to be 3k RPM @75 MPH. A lot of the info for gearing manuals is regarding the 5 speed. My TJ has a .84 overdrive NSG370 close ratio 6 SPEED, 4.0 and 33" tires. So are the recommended gear/rpm combinations in gear 5 @ 1:1, or Gear #6 @.84:1? Currently running a 3.07. One formula 33/30*3.07 = 3.37. So if factory was 30inch tires and I went to 33, that is 110% larger so 3.37 would be the actual ratio required to restore the rpm/gear to factory design? That does not seem right. I must be missing something.
Trying to decide on using 4:10 (LEFT) or 4:56 (RIGHT) I used 33" for my tire size in reaper, which I am now aware might actually be slightly smaller.
I don't crawl. Looking for best drivability and economy IE: A daily driver. Thanks for any and all advice!


View attachment 330670

Personally, I would run a 4.56 in your case. It would be comparable in performance to a factory 6-speed Rubicon on factory 31s.

4.56 will also provide you a bit of headroom in case you ever go to larger tires (though 4.88 would be preferred for 35s, 4.56 would still be perfectly driveable.)

4.30 could be an option, but you can only do that particular ratio with Dana 44 axles in front and rear.

4.10 would certainly be tolerable, maybe not perfect, but with 5th gear being so close to 6th, you would just need to downshift a bit more often.

To give you an actual test of what 4.56 will feel like, here’s something you can try (assuming you already have your 33” tires installed):

5th gear on 3.07s is almost exactly equivalent to 6th gear on 3.73s given the same tire size. So if you drive around pretending you only have a 5-speed, that is what 3.73 will feel like.

4th gear on 3.07s is almost exactly equivalent to 6th gear on 4.56s. So if driving around and on the freeway and 4th gear seems like a decent gear to use in the highway, 4.56 gears will work very well.

Unfortunately there is no similar test for 4.10, but it will be close in performance to the 5th gear / 3.73 test.

 

[Tiros]

Steel, thank you for your reply. Please consider this:
I compare the 6 speed NSG370 with 4.10 to commonly used 5 Speed NV3550 with 4.56. I think the lower gear ratios in the 6 speed help the 4.10 behave like a 4.56. I notice the first 2 gears identical for rpm/speed. Top gear rpm/speed is almost the same too. So it looks to me, like the 6 speed with 4.10 is virtually identical to the 5 speed with 4.56 that is generally recommended. It also looks like 1st gear will be very short if I use 4.56 with the 6 speed. I am now leaning heavily toward the 4.10, wouldn't you agree?

6spd/4.10 -> 5spd/4.56

 

[Steel City 06]

Steel, thank you for your reply. Please consider this:
I compare the 6 speed NSG370 with 4.10 to commonly used 5 Speed NV3550 with 4.56. I think the lower gear ratios in the 6 speed help the 4.10 behave like a 4.56. I notice the first 2 gears identical for rpm/speed. Top gear rpm/speed is almost the same too. So it looks to me, like the 6 speed with 4.10 is virtually identical to the 5 speed with 4.56 that is generally recommended. It also looks like 1st gear will be very short if I use 4.56 with the 6 speed. I am now leaning heavily toward the 4.10, wouldn't you agree?

6spd/4.10 -> 5spd/4.56
View attachment 330900

Realistically, you could be happy with either 4.10 or 4.56. Many of the 6-speed users who go to 35s use 4.88 gears, which seem to work quite well with that tire size. One common target for manual TJ owners is to run about 3,000 RPM around 75, which seems to net the most torque without any significant impacts on fuel economy.

Consider that a TJ Rubicon came with 4.10s and tires 2" or so smaller than yours, even with the NSG370. Those RPMs are perfect fine to run for an extended period; in some cases (like the 6-speed Rubicon and in the 3 speed autos) they did that from the factory.