Build Advice

Need advice please...

Objective:
- Rebuild a '12 JKU that will run 37s on full floats and be comfortable at highway speeds. I'm trying to avoid building something that will need to be trailered for 1500+ mile drives.
- Would really like to have some decent turn radius and not be too wide in wooded trails
- Jeep IS NOT a daily driver.
Optional: Keep the door open to someday run 40s

My initial idea:
Dynatrac Hardcore 60s in standard 68.5 width and 5.13 gearing
ATX Chamber II Beadlocks (4.06" BS)
37x*12.5r17 Coopers STT Pro (I run 37 Coopers ST Maxxs' now and love them)
*I figure the 12.5 may help prevent rubbing (?)
Evo Double D Long Arm (optional with coil overs)
PSC Hydro
*Basically, something 2016-era Rubicat-ish but without the d44 up front and the DTD setup

What I'm replacing/hoping to sell to partially fund:
- OEM Rubicon front axle (Trussed, gusseted, LCA skidded, with RCVs, lower shock relocation brackets, tube seals, Synergy tie rod and BJs, newer unit bearings, Clayton high steer)
I was thinking of selling the axle with all of that as a fully upgraded "ready to bolt-in" and starting fresh
- Teraflex CRD 60 semi float rear axle with ARB (they now offer a full float conversion but it will still only be 67" wide).
- Clayton Premium 3.5" mid arm lift with new coil springs and rebuilt clevs and Johnnies
- Woods 1310 front and rear shafts
- The Coopers I currently have on non-bead lock rims (13k on the tires)

Budget is $25k total, some of the funds will come from the sale of the old stuff.

See any issues with my 'plan'?
What would you do?

I'm running the 60/60 Hardcore package with the long arm bolt on coilover kit. I would highly recommend the King bumstops front AND rear. Also if you are planning on running this for long stretches on the highway I would consider going with 4.88s. I've got 5.13s and 37s and while it great on the trail I feel it's a little overgeared when I'm on the freeway.

Agreed on 4.88s. I’ve driven both and 5:13s are great off-road but run at high rpms for long highway runs aren’t the best. There’s little difference off-road with the 4:88s vs 5:13s in my opinion at-least. I vote 4:88.


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Just to verify, those are 8 lugs right? I did the chamber pro II's and STT pros, but due to budget reasons, stock axles and 5 lugs. So now when it's time for an axle upgrade, I have to buy new wheels again!

Go with the 13.5's, they fit fine on my rig with 3" lift and trimmed fenders.

I vote 5.13. I run 4.88's and recently did 5000 miles of highway Florida to Moab and back. If the highway goes anything above level, it downshifts to 4th. Hit a steep hill, headwind over 70mph, or pulling a camper, it's in 3rd more times that I wish and screaming at 4000+ rpms. I wonder if 5.13's would let it hold a higher gear longer in the transmission.

zimm said:

Just to verify, those are 8 lugs right? I did the chamber pro II's and STT pros, but due to budget reasons, stock axles and 5 lugs. So now when it's time for an axle upgrade, I have to buy new wheels again!

Go with the 13.5's, they fit fine on my rig with 3" lift and trimmed fenders.

I vote 5.13. I run 4.88's and recently did 5000 miles of highway Florida to Moab and back. If the highway goes anything above level, it downshifts to 4th. Hit a steep hill, headwind over 70mph, or pulling a camper, it's in 3rd more times that I wish and screaming at 4000+ rpms. I wonder if 5.13's would let it hold a higher gear longer in the transmission.

Click to expand...

I down shift in those situations, with 4.88 and 35’s, pulling a camper, or on long hills, but not as bad as 4.56 would. If you want it strong, go 5.13. You’ll want it if you tow.


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zimm said:

Just to verify, those are 8 lugs right? I did the chamber pro II's and STT pros, but due to budget reasons, stock axles and 5 lugs. So now when it's time for an axle upgrade, I have to buy new wheels again!

Go with the 13.5's, they fit fine on my rig with 3" lift and trimmed fenders.

I vote 5.13. I run 4.88's and recently did 5000 miles of highway Florida to Moab and back. If the highway goes anything above level, it downshifts to 4th. Hit a steep hill, headwind over 70mph, or pulling a camper, it's in 3rd more times that I wish and screaming at 4000+ rpms. I wonder if 5.13's would let it hold a higher gear longer in the transmission.

Click to expand...

That was my experience. running a loaded jku on 37s on a straight level highway was fine with 4.88. Rpms around 2700. But any incline or headwind was a downshift. It was really apparent in Colorado and Utah. If I could go back I would probably go 5.13. Lol why don’t I listen.


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wjtstudios said:

Agreed on 4.88s. I’ve driven both and 5:13s are great off-road but run at high rpms for long highway runs aren’t the best. There’s little difference off-road with the 4:88s vs 5:13s in my opinion at-least. I vote 4:88.

Click to expand...

I should have mentioned that my Jeep is a manual in my OP.
I have 4.88s now and its 6th is an OK cruising gear. Being able to go to 5th is good when you need some overdrive action though.

RSQCON said:

I'm running the 60/60 Hardcore package with the long arm bolt on coilover kit. I would highly recommend the King bumstops front AND rear. Also if you are planning on running this for long stretches on the highway I would consider going with 4.88s. I've got 5.13s and 37s and while it great on the trail I feel it's a little overgeared when I'm on the freeway.

Click to expand...

You say you're running the Hardcore package with coil overs?
Which coil setup?
What wheel backspace and tire width (12.5, 13.5)?
Any rubbing issues?

ctznarcane said:

You say you're running the Hardcore package with coil overs?
Which coil setup?
What wheel backspace and tire width (12.5, 13.5)?
Any rubbing issues?

Click to expand...

Yes hardcore and Evo bolt on coilover setup with their long arms. 37x12.5" Krawlers on KMC Machetes w/ 3.5" bs. I had ORE set the coilovers as low as possible and zero rubbing but I am running Crawler Conceptz fenders. With the factory fenders I kept pulling clips out up front on the passenger side.

For those running 4.88s and talking about the need to downshift on any grade it's really no different with 5.13s. I'm just saying if your going to do a lot of highway miles id strongly consider 4.88s. I trailer most places we go cause its easier with the kids.