2003 TJ Rubicon Build - Need Suggestions

[Justice4Peanut]

Hey everyone. New member and recently bought a 2003 TJ Rubicon. The Jeep is super clean with only 103k miles. It has the 4.0 engine with 42RLE transmission and, obviously, Dana 44s front and rear. The previous owner put on a 2” or 2.5” lift with 35x12.5r15 Maxxis Razr tires on 15x8 wheels with 3.75” backspacing. I plan on having the Jeep regeared with additional upgrades to the suspension and steering as described more below.

I’ve done a bunch of reading on this website and I’m hoping I can get some suggestions on my planned build. First, a little bit about me and my planned use since I know it has an impact on how I should plan my build.

I am not a complete noob when it comes to off roading, but I’m certainly no expert either (and will never be). I would still consider myself a beginner – maybe a high beginner. My previous rig was an older Nissan Xterra with a 4” suspension lift and 32” tires. It did ok, but was not super robust and seemed limited by its torsion bar/leaf spring suspension. This, plus I always wanted a Jeep and found a clean TJ, is why I moved to the Wrangler.

The TJ will not be a daily driver, although it will be driven periodically around town and, of course, to the trails. My previous off roading and planned off road use is mostly desert exploring and minor/moderate rock "crawling". For rock crawling use, think the easier trails at Sand Hollow and the Tie Rod Canyon and Rocky Gap trails in Las Vegas. Below are a couple of Google photos I found that are illustrative of the type of “crawling” I have done and plan on doing.

You will not find me doing the more advanced rock crawling stuff like you see below. I just don’t feel the need to terrify myself.

Now to my planned build and my shameless solicitation for feedback and suggestions. I am aware of the costs for the various upgrades. For purposes of this mental exercise, let’s assume price is not a factor (within reason). I’d rather spend the money now and end up with a TJ that suits my planned uses.

Suspension/Steering – I have ordered a 4” short arm suspension lift (Core control arms and the rest Currie/Rock Jock components) with the CurrectLync steering upgrade. I also plan on installing the SwayLoc system in the front and a hydroboost assist for the brakes.

• This seems like a good system based on what I have read here.
• I do not plan on doing any long arm, LCoG, or stretch upgrades for now (or probably ever, if I’m being honest with myself).
• The largest tires I ever plan on running are the 35’s that are currently on it.
• I do not want to put a body lift on it.
• I currently do not plan on running tube fenders (more like flat fender flares), but I am open to this possibility.
• For a vehicle that will mostly be used off road, what your thoughts on keeping the 35’s with the 4” suspension lift? Will the lack of body lift hamper the suspension articulation enough that I should just go with 33’s?

Tire Size – As noted, the TJ currently has 35’s on it.

• If it makes sense, I am open to selling the tires (keeping the wheels) and putting 33’s on it.
• I am a little concerned (maybe irrationally?) about such large tires on the short wheelbase with respect to stability.
• With my planned use and 4” suspension lift as described above, what are your thoughts about keeping the 35’s vs. putting 33’s on it?

Regearing – The TJ currently has the stock 4.10 gearing.

• No matter what tires I ultimately run, I am having it regeared and already have an appointment later this month to do so.
• My factory lockers work, and I plan on keeping them.
• I have looked a several gearing calculators and my default strategy (feel free to correct me if I’m wrong) is to somewhat match (but still geared a little bit lower) the freeway RPM’s of a stock Rubicon gear/tire configuration.
• If I keep the 35’s, the calculator shows 4.88 is closest to the stock configuration. However, I think I would still want to go to 5.13. I know the regearing FAQ on this forum suggests either 5.13 or 5.38.
• If I go with 33’s, 4.56 is the closest to stock configuration. However, I think would want to run at least 4.88. Again, I know the regearing FAQ on this forum suggests 5.13.
• Depending on whether I go with the 35s’s or 33’s (such a hard decision!) and given my planned use, what are your thoughts on the gear ratio?
• I also wonder if I should pick a somewhat taller gear ratio in the event I keep the 35’s for now but decide to go to 33’s later?

I really appreciate any guidance you can give me.

 

[Wildman]

Don't be opposed to running a body lift. The size recommended is a 1.25" sold by Black Magic Brakes. It's what is recommended for 35" tires with a 4" suspension lift. This isn't the body lift of old.

As for gearing yes you want 5.13 gears. While 4.88 brings it back close to stock gearing you have to account for the larger tires and roll resistance plus the added wind resistance from being taller. And you'll be fine running 33" tires with the 5.13 gears also. The 4.0 likes to rev and it's not going to hurt it.

And welcome to the forum.

 

[LakeBeard]

x2 on the body lift, this will allow the tummy tuck you will want if your playing in the rocks. stay on 35's and go w/ 5.38 gears

 

[OffroadTreks]

Personal opinion, when you're kinda green, go run some of those areas you want to visit with it how it is now. So you know how it is. Know it's limits. And you'll be able to actually tell what made a difference as you do your mods.

When you're a guy whose been building rigs, you can pretty much just go build a rig. But when you're new, if you go straight into crazy, you won't have a feel for how it was. I think something is lost in that. And have seen a lot of guys with no experience and a lot of money, upside down. While a guy in a lesser rig with years more experience walks by.

 

[tworley]

Determine your tire size, build for that.

If 35s...
- 5.38s
- 1.25" body lift

Any other questions we can answer along the way. But you need to determine your tire size.

 

[Wildman]

As OffRoad Treks suggested take it out how it is built now and play with it. One thing to NOTE: You want to lock your rear lock the minute you get off-road since the limited slip portion of it is known to be weak and can break. So you want to lock your rear locker at all times when off-road. If you do a search on here you'll find it discussed.
To add to what Trek said, don't build past your skill level. Learn to wheel it as is then when you find yourself pushing past what your rig is capable of then modify more.
And like Tworley said determine what tire size you're going with and then pick your gear ratio.

As to if running 35" tires on a SWB rig is not safe? There are many here who have done so without any issues. I was at one point running 38" tires on a 95" WB TJ. They were short 38" tires though.

I'm now sitting @ 100" WB and 38x13.5x17 tires.

 

[Irun]

Having run the 42RLE for 15+ years, follow what @tworley said for gearing. With the Rubicon 44s, stick with 5.38. That ratio will work for either 33" or 35" tires. In either case, the difference in RPMs is only a little over 100. FWIW, with a 33" tire and 5.38 gears you're still under 2700 rpms at 70mph.

 

[Justice4Peanut]

Great advice here. Thank you so much!

 

[jjvw]

With your transmission, a 32" tire should have 5.38 gears.

 

[Justice4Peanut]

Hey everyone. I appreciate the advice given here and another question. I have ordered almost all my parts for the 4" short arm lift, including a Tom Woods driveshaft.

Upon closer inspection of the Jeep, it turns out the previous owner had a 1" transfer case drop installed when the 2” or 2.5” lift was installed. With the vehicle being a Rubicon, it is my understanding the TC drop was not necessary. Not sure why they had it installed.

From my searches on this forum, I think the TC drop is not necessary for the Rubicon models - even with my 4" lift. When I install the lift kit, do you think I should just eliminate the TC drop?

Thanks again.

 

[NashvilleTJ]

Hey everyone. I appreciate the advice given here and another question. I have ordered almost all my parts for the 4" short arm lift, including a Tom Woods driveshaft.

Upon closer inspection of the Jeep, it turns out the previous owner had a 1" transfer case drop installed when the 2” or 2.5” lift was installed. With the vehicle being a Rubicon, it is my understanding the TC drop was not necessary. Not sure why they had it installed.

From my searches on this forum, I think the TC drop is not necessary for the Rubicon models - even with my 4" lift. When I install the lift kit, do you think I should just eliminate the TC drop?

Thanks again.

Did you order adjustable control arms?

 

[Justice4Peanut]

Did you order adjustable control arms?

I did. Double adjustable control arms.

 

[jjvw]

Hey everyone. I appreciate the advice given here and another question. I have ordered almost all my parts for the 4" short arm lift, including a Tom Woods driveshaft.

Upon closer inspection of the Jeep, it turns out the previous owner had a 1" transfer case drop installed when the 2” or 2.5” lift was installed. With the vehicle being a Rubicon, it is my understanding the TC drop was not necessary. Not sure why they had it installed.

From my searches on this forum, I think the TC drop is not necessary for the Rubicon models - even with my 4" lift. When I install the lift kit, do you think I should just eliminate the TC drop?

Thanks again.

There is nothing about the Rubicon that changes how it responds to a spring lift. There comes a point where the driveshafts need to be addressed and this occurs in the same range as a non-Rubicon.

The one and only difference is that the Rubicon transfer case does not have a slip yoke to eliminate. Meaning that a double cardan rear driveshaft can be attached directly to it without modification. Adjustable control arms are also still required for this.

 

[Justice4Peanut]

There is nothing about the Rubicon that changes how it responds to a spring lift. There comes a point where the driveshafts need to be addressed and this occurs in the same range as a non-Rubicon.

The one and only difference is that the Rubicon transfer case does not have a slip yoke to eliminate. Meaning that a double cardan rear driveshaft can be attached directly to it without modification. Adjustable control arms are also still required for this.

True, and I bought a Tom Woods driveshaft in anticipation of the 4" lift. My question is, when installing the lift and driveshaft, should I just get rid of the TC drop? From my research, it doesn't seem necessary for my setup. I guess it probably doesn't hurt to keep it on as it seems the only downside is a slight loss of ground clearance.

 

[jjvw]

True, and I bought a Tom Woods driveshaft in anticipation of the 4" lift. My question is, when installing the lift and driveshaft, should I just get rid of the TC drop? From my research, it doesn't seem necessary for my setup. I guess it probably doesn't hurt to keep it on as it seems the only downside is a slight loss of ground clearance.

Not having a lowered center skid is the point of it all.

A double cardan rear driveshaft and adjustable control arms are what allow some of us to raise the entire drivetrain higher than factory.

 

[Justice4Peanut]

Not having a lowered center skid is the point of it all.

A double cardan rear driveshaft and adjustable control arms are what allow some of us to raise the entire drivetrain higher than factory.
View attachment 624238

That makes sense. Thank you. I think I'm inclined to just remove the TC drop when I install the lift kit. I don't see a reason to keep it.

 

[Rickyd]

True, and I bought a Tom Woods driveshaft in anticipation of the 4" lift. My question is, when installing the lift and driveshaft, should I just get rid of the TC drop? From my research, it doesn't seem necessary for my setup. I guess it probably doesn't hurt to keep it on as it seems the only downside is a slight loss of ground clearance.

If you have a double cardinal rear shaft and adjustable arms you can get rid of the tcase drop. You will likely need to adjust transfer case linkage and exhaust when doing so

 

[Justice4Peanut]

If you have a double cardinal rear shaft and adjustable arms you can get rid of the tcase drop. You will likely need to adjust transfer case linkage and exhaust when doing so

Understood. Thank you for the reply.

 

[Mellow_Jello374]

Don't be opposed to running a body lift. The size recommended is a 1.25" sold by Black Magic Brakes. It's what is recommended for 35" tires with a 4" suspension lift. This isn't the body lift of old.

As for gearing yes you want 5.13 gears. While 4.88 brings it back close to stock gearing you have to account for the larger tires and roll resistance plus the added wind resistance from being taller. And you'll be fine running 33" tires with the 5.13 gears also. The 4.0 likes to rev and it's not going to hurt it.

And welcome to the forum.

 

[Mellow_Jello374]

Welcome to the forum!!!
I would recommend taking it out before any mods, you’ll be able to see what needs work and what you can leave alone for now. You don’t want to go overboard plus it’s already very well built