37s, 38s, 39s, and 40s! What would you have done differently?

[Koolcarguy]

The good old internet wisbow of replace everything because that's what I did and it worked. I've waited until the ball joints actually wear out before replacing them, because there's no need. The 1st JLUR made it to 40k miles on the stock ball joints and 37s. 2nd JLUR made it 32k miles on the stock ball joints and 39s. The JT still has stock ball joints at 25k miles on 37s. Between the 3 we've owned, wheeled all over the country, and put 150k miles on, I've never had to replace the stock tie rods. All 3 ended up with flipped drag links and raised track bar mounts because I agree that geometry is important. Replacing parts that don't need replacing is just pissing money away. We've run everything from the rubicon trail to Pritchett Canyon to John Bull, all on stock shafts. Now granted we have decades of wheeling experience and are fully prepared to change an axle shaft etc on the trail so I'm comfortable with potentially finding the limit of the stock parts. Some aren't so they'll drop $35k right out the gate (hopefully they still have the skills to make trail repairs because anything can break).

Agreed I have to run those same parts for 50k+++ miles off road thousands of those miles. I think it's all preference especially if your not afraid to repair on the trail which we do and as you stated all parts can break period. As far as gears I run stock gears in both my Jt diesels with 37's with absolutely zero problem and more power then I've ever needed on a trail.

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[n0arp]

The good old internet wisbow of replace everything because that's what I did and it worked. I've waited until the ball joints actually wear out before replacing them, because there's no need. The 1st JLUR made it to 40k miles on the stock ball joints and 37s. 2nd JLUR made it 32k miles on the stock ball joints and 39s. The JT still has stock ball joints at 25k miles on 37s. Between the 3 we've owned, wheeled all over the country, and put 150k miles on, I've never had to replace the stock tie rods. All 3 ended up with flipped drag links and raised track bar mounts because I agree that geometry is important. Replacing parts that don't need replacing is just pissing money away. We've run everything from the rubicon trail to Pritchett Canyon to John Bull, all on stock shafts. Now granted we have decades of wheeling experience and are fully prepared to change an axle shaft etc on the trail so I'm comfortable with potentially finding the limit of the stock parts. Some aren't so they'll drop $35k right out the gate (hopefully they still have the skills to make trail repairs because anything can break).

I think you missed some nuance. The larger you go and more time you spend off-road, the more you have to address for each point. If you are throwing 37s on and spend 98% of your time on paved roads, you can get away without a lot of investment. Which is what I alluded to in my post.

I destroyed the stock ball joints on my JLUR in less than 30K miles. The first 14K of that on stock 33s, the rest on 37s. Might have even been under 20K, as that was a long time ago and I don't recall exact details. The larger you go, and more often you go off-road, the more important all those upgrades are. An occasional trail run is different than thousands of miles each year in the dirt.

 

[Zachanadandy]

I think you missed some nuance. The larger you go and more time you spend off-road, the more you have to address for each point. If you are throwing 37s on and spend 95% of your time on paved roads, you can get away without a lot of investment. Which is what I said in my post.

I destroyed the stock ball joints on my JLUR in less than 30K miles. Half of that on stock 33s, half on 37s. Might have even been under 20K, it's been a long time since I got rid of it. The larger you go, and more often you go off-road, the more important all those upgrades are. An occasional trail run is different than thousands of miles each year in the dirt.

Our AZ property is 15 miles out a washboarded dirt road and the JT gets wheeled in the desert for hundreds of miles several times a year, all the miles have been on 37s. The 2019 JLUR had 63k miles on it when it was stolen, 26 badge trails all over the country and hundreds of others. Pritchett, cliffhanger, gutbuster, John Bull, the rubicon, as some of the harder ones but definitely thousands of trail miles. These aren't occasional wheelers but they aren't trail only by any means. Driven to and from hard trails all over the country on big tires and stock tie rods.

 

[n0arp]

Our AZ property is 15 miles out a washboarded dirt road and the JT gets wheeled in the desert for hundreds of miles several times a year, all the miles have been on 37s. The 2019 JLUR had 63k miles on it when it was stolen, 26 badge trails all over the country and hundreds of others. Pritchett, cliffhanger, gutbuster, John Bull, the rubicon, as some of the harder ones but definitely thousands of trail miles. These aren't occasional wheelers but they aren't trail only by any means. Driven to and from hard trails all over the country on big tires and stock tie rods.

I also twisted the rear splines on it shortly after moving to 37s. You obviously take a lot more care not to damage things, while I prefer to build them up and send it. I'm sure driving style plays a large role in what is necessary as well.

 

[Zachanadandy]

I also twisted the rear splines on it shortly after moving to 37s. You obviously take a lot more care not to damage things, while I prefer to build them up and send it. I'm sure driving style plays a large role in what is necessary as well.

I have no problem jumping the mojave. I won't shy away from an obstacle where there's potential body damage. But I do wheel them like they are $50k+ rigs with straight sheetmetal. They aren't rock bouncers or $3500 beaters like my old XJ. If you're really going full send on 37s+ in a 6klb rig you need tons at a minimum.

 

[Zachanadandy]

Yep, that's why I burned down my wife's stock rubi tires and we put 100k on the stock parts. I couldn't bring myself to just throw all that stuff away.

Completely a fan of replace what is necessary as it's necessary. Or, if you're going nuts with a build, lineup someone else that can benefit from your stock factory parts, say someone with a stock rig with more miles, or a lower trim model, etc.

Jim

I hate KO2s so the stock 35s came off the xr by 15k miles and we went to 39s. Sold the ko2s for $700 so no loss there. The components that don't perform can go fresh out the gate. Soft factory springs, mushy under-dampened shocks with short travel, etc don't cut it. But changing out factory parts for aftermarket parts that perform the same? Pass.

 

[Zachanadandy]

Now we’re talking!

Drop some more knowledge bombs please.

Axles and then what else? What order would you go in upgrading parts?

I can see we’re getting somewhere with this.

Going to tons means full build all at once. You'll need new wheels, it would be insane to run stock tires on tons geared for 40s, you'd need the suspension upgrades for the whole deal. You can go the other way, build the suspension you want and then upgrade axles, wheels, and tires, but starting with axles basically means you save the pile of cash and order a truckload of parts and go. Stock steering doesn't work with tons either so to even drive it you need that upgrade too. Driveshafts need upgraded too. No order to it, as you need to do all of it.

 

[Alpine Warthog]

If it hasn't been said yet, you WILL get inchitis. Tell yourself that 35s are the biggest you're going to go, you're lieing to yourself and the rest of us. Those of us that never go any bigger spend the rest of our lives with that unscratched itch. LOL. I told myself 33s were all the bigger I'd go on my XJ. I'm trying to figure out 40s these days.

 

[Billyj7175]

I started off with 37's and regeared with 4:88's. Later on I went with 38's and wish I would have gone with 5:13's.

 

[darkhorse13]

1) Regear. The people who tell you "it is fine" are delusional and/or trying to justify being too cheap to do so.
2) Lift kit (don't cheap out) including geometry corrections.
3) Upgrade your ball joints and all steering linkage.
4) Also upgrade your axle shafts and/or consider other axle upgrades.
5) Consider the PS Boost Kit or hydraulic assist.

^^ Perfect list!!! ^^

up to 37's = bullet points #1 - #3 to "build it properly" (yes, all steering related linkage from tie rod, drag link, track bar and, dare I say, steel knuckles to go along with those upgraded ball joints)

over 37's = #4 & #5 will squeeze out the last drop of juice before 1 ton swap (depending on your wheeling style)

 

[pvn.jt24]

Going to tons means full build all at once. You'll need new wheels, it would be insane to run stock tires on tons geared for 40s, you'd need the suspension upgrades for the whole deal. You can go the other way, build the suspension you want and then upgrade axles, wheels, and tires, but starting with axles basically means you save the pile of cash and order a truckload of parts and go. Stock steering doesn't work with tons either so to even drive it you need that upgrade too. Driveshafts need upgraded too. No order to it, as you need to do all of it.

Definitely no order to it, but it’s nice to slowly accrue all the parts needed to eventually make those ton axles usable on the rig.

I think I’m seeing more of a debate on how things should be done versus seeing what people would have done differently with their current rigs.

If you went 37s, what would you have upgraded first versus what you actually bought first for your JT? Same goes with those running 38s, 39s, 40s?

 

[n0arp]

If you went 37s, what would you have upgraded first versus what you actually bought first for your JT? Same goes with those running 38s, 39s, 40s?

I twisted shafts first, and ball joints went second. Steering got sloppy fairly quick so I upgraded it all. That was on 37s. Went to 40s after a while and my JTRD is also on 40s. When I put 37s on my JLUR, it took me about five miles to decide to regear to 5.13. So for 37s, if I had to choose an order of importance based on my personal experiences: steering linkage first, then regear and shafts at the same time. That's if you have to space it out and can't do it all at once. Steering is more likely to be a safety item than twisted splines or acceleration loss from gearing... so that's justification for the prioritization.

A lot of the time it's easier to build it rather than deal with a break when that break inevitably happens at the worst time/place. You'll still break built stuff, but it's less likely and more importantly, less often.

 

[Zachanadandy]

Definitely no order to it, but it’s nice to slowly accrue all the parts needed to eventually make those ton axles usable on the rig.

I think I’m seeing more of a debate on how things should be done versus seeing what people would have done differently with their current rigs.

If you went 37s, what would you have upgraded first versus what you actually bought first for your JT? Same goes with those running 38s, 39s, 40s?

If the plan is eventually tons, then pretty much every upgrade you do to axles/ steering is throwing money away was my point. If you're going to tons you can do suspension upgrades and even tires as that stuff can stay/still work with the new axles. Regearing is very expensive and despite what some on here argue you can get by just fine on 37s and the stock 4.10s. That regear money is a decent start toward your 1 ton fund. For me I wouldn't have done anything different and I went to 37s before the 1st oil change. The AEV 2" spacer lift was paid for by selling the wife's JLUR 35" take offs and the 37s were $200 cheaper than I sold the stock 33s for thanks to a crazy Walmart sale I found on this forum. My initial build was basically free and was fully functional at freeway speeds in the desert. I wanted increased stability on high speed washboards so front control arm drop brackets and the rock krawler rear 4 link were next. If I had it to do over again and money were no object that's a different animal, but for what I have in it is real hard to find anyone in a Jeep who keeps up in the dirt. Obviously long arms, tons, 40s, 3.0" bypass shocks, and a hellcat swap would make it way better than it is, but I'm not about to go 6 figure build as the divorce that would follow would make that look cheap.

 

[darkhorse13]

I think I’m seeing more of a debate on how things should be done versus seeing what people would have done differently with their current rigs.

If you went 37s, what would you have upgraded first versus what you actually bought first for your JT? Same goes with those running 38s, 39s, 40s?

Ha, true, we did stray away from the OG question...

Short Story:
What would I have done differently = I would have done upgraded ball joints and steel knuckles at the beginning and done the re-gear sooner knowing that I was going to run 37's

Long Story:
No major regrets, and here's why:
1) I bought a 2020 JTR used with 8600mi in June 2021. Immediately I knew I wanted 37's and the minimal amount of lift to clear them. So, we'll start the conversation there = 37's were the goal for an overland rig... as others have said = try to know your end goal as early as possible (also knowing it might be tweaked)
2) I planed my first upgrades around running 37's with the intent on NOT replacing parts as they wear out. I wanted to future-proof right out of the gate (which is not always easy to plan as even the aftermarket has "inferior" parts, but I researched for 3 months and gambled on my preparedness) Why get stranded or crawl under your Jeep multiple times? Time is also money.
3) I wanted a rock solid steering platform from the start so I went with sector brace/drag link/tie rod/track bar/upper& lower control arms before even ordering the shocks and springs = I have no regrets on this decision to this day (60k miles on those parts). Everything was blown apart at one time and saved on labor costs.
4) One regret = I skipped upgraded ball joints at the get-go and replaced the OEMs with Dynatrac HD rebuilables around 46k miles. I admittedly did not know in 2021 as a new Jeep owner what I know now about ball joint failure and death wobble
5) Second regret = I waited 2 years before regearing to 5.13's. What a difference this made in gas mileage, power and shifting.

Longer Story:
Once you start modding it's hard to stop. I've been thru 3 sets of different springs and shocks chasing an idea of a "perfect ride" and I'm still stupidly wanting to change them again. Ok, so 3rd and on-going regret is not being satisfied with what I have that is working just fine. I also wish I could could stay off Instagram and this forum sometimes thinking I need a 392 + tons + 42's... I mean I do and I don't I'm rambling now, but at the end of the day I really like the Top 5 list that @n0arp put together. Even though it comes across as a "how it should be done" list, it more or less helps you not have to ask the "what would you do differently" because you've already done it... at least in my case.

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