33's - Is this what I need?

[Austin O.]

I just recently made a post about regearing for the 31s that have been on my tj for the past couple years. I have 3.07s currently and was thinking about going up to 4.10s. I said I don't plan to go to 33s for a while, but I started thinking more and decided that I for some reason need 33s... so here I am... And just for fun and because people like pictures, here's a recent photo of my tj.

I've done some research on the forum and put together a list of what I think I need, I want to double check and ask some questions. I am trying to do this relatively cheap while still using good quality parts. It's a daily driver that I want to wheel occasionally. A big part of this though is that I like the look of 33s on a tj done right. Here's my current list:

- BMB 1.25'' body lift
- Rough country 1'' motor mount lift (I know, I know, we don't like that brand... but does it really matter for a motor mount lift? Let me know. Its the cheapest option I could find)
- Freedom offroad 2.5'' lift springs (feedback on this choice please, don't know much about the brand, general consensus seems to be that spring brand doesn't matter like shocks do)
- JKS rear trackbar relocation bracket
- Zj tie rod
- I currently have Rancho RS5000X shocks, for 0-1 inch lifts. I think these are fine to keep, people say they long run?
- Still doing research on what tires I want specifically... currently have Kenda Klever MTs which I am happy with, I like the look, I might just get them in the bigger size
- Are my wheels fine for 33s? 15x8 jeep brand wheels, I don't know what the specific name is, I can figure that out if needed though.
- 4.56 gears - This is where I need the most suggestions/opinions. Do I buy new, do I look for axles with them already installed? (I have a 4.0, 5 speed manual). How feasible is it that I do the work myself? I really want to, I know I can, but is it really a good idea?

I know our tjs are fun and not practical for many things, but out of curiosity, how might gas milage change? I don't have proper gearing now - 3.07s and 31s, I'm getting around 16mpg usually, will I be better with 33s and proper gears (4.56s)?

Ok, tear it apart now please, tell me what I'm doing wrong, what I'm missing, etc. Thanks!

 

[freedom_in_4low]

Those wheels will be fine. You'll probably want spacers if you run a 33x12.5, but you should be able to get by with just a little front lower control arm rubbing if you run 33x10.5. I much prefer the narrower look so that's what I would do. (EDIT: if 15x8...if they're 15x7 you probably won't want a 12.5 on them)

Look at the free length on those springs. Springs don't matter for ride quality but they absolutely matter in other ways ...like how far you can droop before they go loose in the perch. I like Rockjock springs because they make a long spring for the ride height but not so long that they stack solid before they should. Downside is if you have a lot of variability in your weight (such as over landing trips with hundreds of pounds of gear), the long, soft RJ spring may sag a lot when loaded, or require a bunch of rake when unloaded to be level when loaded. In that case you might want a higher rate like OME.

You can try it with your shocks but I think it's more likely than not that they'll be short. Think about it this way...they have about 8" of travel, and you're moving 3" of your downtravel into uptravel. If it's anywhere close to right today, it won't be after that much lift.


It'll likely be cheaper to find axles with the gears already done...but who knows how long it'll take to find the right ones and then you have no idea who did the install or whether they knew what they were doing. I don't think it's necessarily difficult, but it takes patience and a thought process more like engine building or body work than the bolt-off/bolt-on Lego type of assembly that we're used to with most things. And you need some special tools that most people don't have if they haven't done that work. BFH garage has some great videos on regearing and I've convinced myself $5k spent on gear installs is enough and the next time I'm gonna DIY.

 

[MikekiM]

Can you be more specific with what kind of "wheeling" you plan to do?

Mine is a daily driver. I see unmaintained rocky fire roads and soft outer beach sand a handful of times a month. The rest of the time it is my primary ride.

4.0, 5spd,
33x12.5 on 15x10 (working on downsizing to 15x8)
Rancho's
Currie steering
3" SL. No BL.
Dana 30/44

I swapped from stock 3.73 to 4.56 with TruTrac Limited Slip a few years ago and it is one of the best mods I have done. I average about 14mpg. Giggle a little when I drive.. it's a ton of fun. I had the regear done at a local 4x4 shop. It wasn't cheap.

I suspect your wheels should be fine but the offset is going to be critical.

You didn't ask about carrying a 33" spare.. but add some tailgate reinforcement to your list of things to do. The stock carrier will work in the short run but over the long haul you'd be better off with something beefier. MoRyde Exogate, Rugged Ridge Spartacus HD carrier, MoRyde HD hinges or the like

 

[OldBuzzard]

You can play with gear ratios and tire size on http://www.grimmjeeper.com/gears.html.

With your AX-15 transmission and 33" tires, I would recommend 4.88 gears. That will get you 2944 RPMs at 75 MPH. It sounds high, but it's just right. Your gas mileage will probably be fine, maybe even better, since the engine will be working less hard. On the other hand, you may get a bit worse mileage due to the bigger tires and lift. Consider pizza cutters (33x10.5 instead of 33x12.5). Keep the 15x8 wheels, but you might need a spacer to get backspace just right (or not with the pizza cutters).

 

[Austin O.]

Those wheels will be fine. You'll probably want spacers if you run a 33x12.5, but you should be able to get by with just a little front lower control arm rubbing if you run 33x10.5. I much prefer the narrower look so that's what I would do.

Look at the free length on those springs. Springs don't matter for ride quality but they absolutely matter in other ways ...like how far you can droop before they go loose in the perch. I like Rockjock springs because they make a long spring for the ride height. Downside is if you have a lot of variability in your weight (such as over landing trips with hundreds of pounds of gear), the long, soft RJ spring may sag a lot when loaded, or require a bunch of rake when unloaded to be level when loaded.

You can try it with your shocks but I think it's more likely than not that they'll be short. Think about it this way...they have about 8" of travel, and you're moving 3" of your downtravel into uptravel. If it's anywhere close to right today, it won't be after that much lift.


It'll likely be cheaper to find axles with the gears already done...but who knows how long it'll take to find the right ones and then you have no idea who did the install or whether they knew what they were doing. I don't think it's necessarily difficult, but it takes patience and a thought process more like engine building or body work than the bolt-off/bolt-on Lego type of assembly that we're used to with most things. And you need some special tools that most people don't have if they haven't done that work. BFH garage has some great videos on regearing and I've convinced myself $5k spent on gear installs is enough and the next time I'm gonna DIY.

Thanks for the response, I'll check out free length on the springs, what do I want that to be? And Ill definitely look at those videos by BFH, I know that people on the forum highly recommend them!

 

[Austin O.]

Can you be more specific with what kind of "wheeling" you plan to do?

Mine is a daily driver. I see unmaintained rocky fire roads and soft outer beach sand a handful of times a month. The rest of the time it is my primary ride.

4.0, 5spd,
33x12.5 on 15x10 (working on downsizing to 15x8)
Rancho's
Currie steering
3" SL. No BL.
Dana 30/44

I swapped from stock 3.73 to 4.56 with TruTrac Limited Slip a few years ago and it is one of the best mods I have done. I average about 14mpg. Giggle a little when I drive.. it's a ton of fun. I had the regear done at a local 4x4 shop. It wasn't cheap.

I suspect your wheels should be fine but the offset is going to be critical.

You didn't ask about carrying a 33" spare.. but add some tailgate reinforcement to your list of things to do. The stock carrier will work in the short run but over the long haul you'd be better off with something beefier. MoRyde Exogate, Rugged Ridge Spartacus HD carrier, MoRyde HD hinges or the like

I see old forest service roads probably once or twice a month. I'd love to get into some actual trails more often with slightly more technical stuff. Thanks for reminding me about the tailgate, I thought about that before, but forgot to put it in the post!

 

[Austin O.]

You can play with gear ratios and tire size on http://www.grimmjeeper.com/gears.html.

With your AX-15 transmission and 33" tires, I would recommend 4.88 gears. That will get you 2944 RPMs at 75 MPH. It sounds high, but it's just right. Your gas mileage will probably be fine, maybe even better, since the engine will be working less hard. On the other hand, you may get a bit worse mileage due to the bigger tires and lift. Consider pizza cutters (33x10.5 instead of 33x12.5). Keep the 15x8 wheels, but you might need a spacer to get backspace just right (or not with the pizza cutters).

Thanks for the help! I'm definitely considering the 33x10.5 tires, and still learning about gear ratios, definitely more research to be done there!

 

[freedom_in_4low]

Thanks for the response, I'll check out free length on the springs, what do I want that to be? And Ill definitely look at those videos by BFG, I know that people on the forum highly recommend them!

Not so much a target, just look at a few options and see what makes sense for you. I don't have the number off the top of my head but if you measure your spring height, and your shock length, at ride height, and take the difference, you can see how long your spring would be with the shock at full extension, and you want a free length at least that.

Rockjock 4" springs I think are 22" and change, so a 3" should be in the 20-21 neighborhood.

 

[Austin O.]

Not so much a target, just look at a few options and see what makes sense for you. I don't have the number off the top of my head but if you measure your spring height, and your shock length, at ride height, and take the difference, you can see how long your spring would be with the shock at full extension, and you want a free length at least that.

Rockjock 4" springs I think are 22" and change, so a 3" should be in the 20-21 neighborhood.

Makes sense, thanks!

 

[Jamison C]

I remember from your other thread you mentioned you were in a hilly area. For the 5-speed I would go 4.88 if you go 33s, puts you about 3k RPM at 75mph. I remember having 33s and 4.56 and while it was more than adequate, a little more would have been nice. Theres a lot more weight and rolling radius and the extra step up from the standard recommendation of 4.56 is better when you’re doing lots of grades.

*EDIT* just saw what @OldBuzzard posted above. His points on why using 4.88 would be ideal are spot on.

 

[deadbeat son]

- Are my wheels fine for 33s? 15x8 jeep brand wheels, I don't know what the specific name is, I can figure that out if needed though.

The wheels in your photos aren't 15x8, they're the Ecco wheels, which are 15x7. They'll work fine for 33x10.50, but many tire shops won't mount a 33x12.50 on them. With 5.5" of backspacing, the tires may rub on control arms when turning sharply. You may want to space your steering stops or add wheel spacers, such as the Spidertrax 1.25" or H&R 1" spacers.

 

[Austin O.]

The wheels in your photos aren't 15x8, they're the Ecco wheels, which are 15x7. They'll work fine for 33x10.50, but many tire shops won't mount a 33x12.50 on them. With 5.5" of backspacing, the tires may rub on control arms when turning sharply. You may want to space your steering stops or add wheel spacers, such as the Spidertrax 1.25" or H&R 1" spacers.

Thanks for that correction! I had always assumed they were 15x8…

 

[glowell222]

Kenda makes a 15 x 9.5.

 

[JMT]

I just recently made a post about regearing for the 31s that have been on my tj for the past couple years. I have 3.07s currently and was thinking about going up to 4.10s. I said I don't plan to go to 33s for a while, but I started thinking more and decided that I for some reason need 33s... so here I am... And just for fun and because people like pictures, here's a recent photo of my tj.

View attachment 556692

I've done some research on the forum and put together a list of what I think I need, I want to double check and ask some questions. I am trying to do this relatively cheap while still using good quality parts. It's a daily driver that I want to wheel occasionally. A big part of this though is that I like the look of 33s on a tj done right. Here's my current list:

- BMB 1.25'' body lift
- Rough country 1'' motor mount lift (I know, I know, we don't like that brand... but does it really matter for a motor mount lift? Let me know. Its the cheapest option I could find)
- Freedom offroad 2.5'' lift springs (feedback on this choice please, don't know much about the brand, general consensus seems to be that spring brand doesn't matter like shocks do)
- JKS rear trackbar relocation bracket
- Zj tie rod
- I currently have Rancho RS5000X shocks, for 0-1 inch lifts. I think these are fine to keep, people say they long run?
- Still doing research on what tires I want specifically... currently have Kenda Klever MTs which I am happy with, I like the look, I might just get them in the bigger size
- Are my wheels fine for 33s? 15x8 jeep brand wheels, I don't know what the specific name is, I can figure that out if needed though.
- 4.56 gears - This is where I need the most suggestions/opinions. Do I buy new, do I look for axles with them already installed? (I have a 4.0, 5 speed manual). How feasible is it that I do the work myself? I really want to, I know I can, but is it really a good idea?

I know our tjs are fun and not practical for many things, but out of curiosity, how might gas milage change? I don't have proper gearing now - 3.07s and 31s, I'm getting around 16mpg usually, will I be better with 33s and proper gears (4.56s)?

Ok, tear it apart now please, tell me what I'm doing wrong, what I'm missing, etc. Thanks!

I don’t like the JKS rear trackbar relocation bracket. It’s only about 9* angle and the Currie is 19*, which gives you more room back there

Don’t know about the shocks. You can figure that out when you install the springs.

15x8 wheels are

4.88 gears for the 5-speed and 33’s. I’m sick and tired of people repeating the Jerry mantra of 4.56. There’s no substantive difference between the NV3550 and the AX-15. They both should get 4.88 with 33’s.

 

[UND_Sioux]

My first question is how fast do you drive? Just keep in mind that it is recommended to keep the driveshaft speed somewhere between 2500 to 2800 rpms at 60 mph. With your 31s and 3.07s, you are spinning the driveshaft at 2030 rpm at 60 mph. With 33s and 4.56s, your driveshaft speed will now be 2830. That will be fine, but if your driveshafts are out of balance a bit or joints a bit worn, it will be apparent when you make the changes.

 

[D's Jeep Wrld]

Kenda makes a 15 x 9.5.

In a 33" diameter too

That kenda m/t2 is a sexy tire! I love me some pizza cutters,I get more grip on the rocks with my current Dextero Dat1's 10.5" wide tires over the 12.5" wides I had on my Lj so I'm wondering if a 9.5 would be where grip could increase even more or I would be at a point of where the gain would be quite minimal.....
I'd like to get me 2 sets of tires one for the street and one for the rocks,heck I may buy both of the same tire,but some stickies wouldn't sound bad.....although my wallet may not like that

 

[MikekiM]

I don’t like the JKS rear trackbar relocation bracket. It’s only about 9* angle and the Currie is 19*, which gives you more room back there

Don’t know about the shocks. You can figure that out when you install the springs.

15x8 wheels are

4.88 gears for the 5-speed and 33’s. I’m sick and tired of people repeating the Jerry mantra of 4.56. There’s no substantive difference between the NV3550 and the AX-15. They both should get 4.88 with 33’s.

My choice for 4.56 over 4.88 wasn't influenced by Jerry at all. My local shop worked through it with me and since I wasn't planning to go to 35's I chose 4.56 based on that exercise. The shop know a lot more than I do, and probably a lot more than Jerry does.. though Jerry would never admit it.

As you said, we came to the conclusion there was no great difference between 4.56 and 4.88 unless the plan is to go to 35's. I have no plans or need to go to 35's.

All that said, I have zero regret

 

[JMT]

My choice for 4.56 over 4.88 wasn't influenced by Jerry at all. My local shop worked through it with me and since I wasn't planning to go to 35's I chose 4.56 based on that exercise. The shop know a lot more than I do, and probably a lot more than Jerry does.. though Jerry would never admit it.

As you said, we came to the conclusion there was no great difference between 4.56 and 4.88 unless the plan is to go to 35's. I have no plans or need to go to 35's.

All that said, I have zero regret

2568rpm at 70mph

Or

2748

These are his choices.

 

[JMT]

My choice for 4.56 over 4.88 wasn't influenced by Jerry at all. My local shop worked through it with me and since I wasn't planning to go to 35's I chose 4.56 based on that exercise. The shop know a lot more than I do, and probably a lot more than Jerry does.. though Jerry would never admit it.

As you said, we came to the conclusion there was no great difference between 4.56 and 4.88 unless the plan is to go to 35's. I have no plans or need to go to 35's.

All that said, I have zero regret

 

[Austin O.]

I don’t like the JKS rear trackbar relocation bracket. It’s only about 9* angle and the Currie is 19*, which gives you more room back there

Don’t know about the shocks. You can figure that out when you install the springs.

15x8 wheels are

4.88 gears for the 5-speed and 33’s. I’m sick and tired of people repeating the Jerry mantra of 4.56. There’s no substantive difference between the NV3550 and the AX-15. They both should get 4.88 with 33’s.

Thanks! I’ll look at the Currie one. Doing more research on 4.88 vs 4.56… 4.88 is still going to be fine on the highway? I do drive the highway quite often, it’s a daily