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TJ upgrades to accommodate 37's
July 23, 2021
10:41 am
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Jeff_R
Meadow Vista
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Okay, as I indicated on another thread, I have been think of getting beadlocks with 37’s for my 04 TJ. I know 37’s put more stress on things so I’m looking for advice as to other modifications that may be advisable or necessary to accommodate 37’s.

Here is my current set up:

Rear Dana44 with ARB air locker. Front Dana 30 with ARB air locker and G2 Chromalloy shafts. 4.88 gears and an Atlas 4.3:1 transfer case. I have Genright tube fenders. I have a 4.0 inline six. Let me know if you need any other information.

After upgrading to the Atlas T-case I do have less power going up the freeway to Tahoe. I don’t think I would want to have to go slower so I’m guessing I may need to change the gears. I do get some rubbing on my front long arms when I turn sharp with my 35’s and maybe a very slight rub in the fender area with full articulation. So what do you recommend? Thanks!

July 23, 2021
11:00 am
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JohnDF
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Seems like more lift and wider offset wheels will be in order for sure… or potentially wider axles.

 

Going from 35s to 37s is a bigger jump than most people think it is… you’ll need much lower gearing to make it up Hwy 80, unless you’re okay with falling back with the Suzukis. grin

I’d only be comfortable with wheeling (hard) if I had a D44 front and a D60 rear, and make sure the steering is heavy duty and reinforced at the frame… especially that track bar and steering box.

I used to wheel a lot. . .

July 23, 2021
4:12 pm
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Jamie (K6NUB)
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I know it is a different animal than my JK, but I did not anticipate having to go with larger bump stops up front going from 35s to 37s, I thought the flat fenders would do it but they did not, I would have ripped them off by now without bigger stops. I think John is right, you are going to need the stance wider.

K6NUB

July 24, 2021
7:49 am
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Robert & Amber
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I would leave your TJ just the way it is. 35’s, arb lockers, 4.3:1, 4.88 diffs. And it still has road manners. Pretty ideal really. Great all around jeep. When you start going towards a dana 44 for the front. 37 bead lock is pushing the limit of even a stock dana 44. So the front and rear 44’s would require some upgrades. But then you are in a similar situation you are in now where you can wheel it pretty much any trail around here but still need to be easy on it. So then maybe the best investment is going dana 60’s. But that kind of build is turning your jeep into a whole different kinda jeep. Then you might as well put 40 inch tires under it. Lol. It is really up to you and what you want. 

July 24, 2021
10:59 am
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Specialsoundman
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JohnDF said
Going from 35s to 37s is a bigger jump than most people think it is… you’ll need much lower gearing to make it up Hwy 80, unless you’re okay with falling back with the Suzukis. grin

 

Thanks for mentioning us John, grinEveryone is welcome to join us.thumbs-up It’s always nice to have other running back with us.clap And as Brad has said our speed helps save gas. laughing

If I can't build it, then it's something that should be bought.

July 24, 2021
11:19 am
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Guy and Lynda
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I have 37’s with 5:13 gearing. John is correct in saying this is a large jump. Brakes, gearing, suspension, & more are all involved in jumping into 37’s. You seem to be doing well on trails now. For a large investment, there would be a small difference in performance, but that decision is all yours. Either way, it’ll be a wise choice!

July 26, 2021
8:20 am
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kris_olof
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Budget at least $5-6k to run 37s and north of $10k if you want 1-tons.

Axles and gearing are your two biggest issues going to 37s. I have the 6 speed and 4.88 and will be swapping to 5.38s.  As for axles, even as tough as 30 spline dana 44s are, you will be finding the limits of the shafts and gears with 37s.

Option 1: The cheapest option and one I recommend would be to find a set of JK Rubicon axles and truss them.  Artech and TNT sell JK to TJ conversion trusses that make that part of the swap easy. 5.13 or 5.38 gears. New wheels for the new bolt pattern, new driveshafts, new rear brake lines on the axle, new steering drag link, and long term some RCV or chromo shafts.  The JK axles are about 65″ wide so that should fix any rubbing issues and make the rig a lot more stable but fender coverage becomes essentially nill.  The biggest cost savings is JK rubicon axles already having lockers that just need a switch to operate.  Downsides is you have to deal with all the weak links like c-gussets and you are still only running 44s. But much heavier JKs live on 37s with 44s so TJ will have a much better time of it.

Option 2: Order a custom 44 front (G2, Currie, etc.) and then beef and re-gear the rear axle with a 33 or 35 spline kit, new 33 or 35 spline locker, truss, and 5.13s or 5.38s.  Jantz engineering sells a Jana k4 kit that lets you use the bigger JK44 gears in the older TJ housing.  This is the easiest method but costs more than the JK swap and leaves you with stock width axles and doesn’t upgrade the brakes or front hubs.  Could be paired with a WJ knuckle swap to get better hubs, bearings, and crossover steering but costs a lot for being stuck with stock width axles (60.5″).

Option 3: Super duty axle swap.  Again Artech sells a truss kit that makes this swap easy and you get true full width 70-72″ and true 1 ton axles. Includes all the costs from option 1 and typically will require a modified fuel tank skid plate which isnt smog legal in california.  If you are in a zip that doesn’t smog then gen-right sells a bolt in tank that gives extra room.  Only real downside of this is 8×170 metric lug pattern and how expensive 1 ton parts are.  The donor axles go for $1,000 to 1,500 right now but you will spend at least that again just replacing wearable items.  Unit bearings aren’t cheap.

Option 4: Custom axles.  I did 609s and doing most of the work my self still came out about $11k.  Teraflex has some 63″ wide dana 60s that are pretty ideal but you are looking at $13k before tax.

July 27, 2021
2:25 pm
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Gregulator
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I’m kind of in the same boat as you Jeff. Build the 30/44 I have and stay on 35s or go bigger for 37s. I personally think 37s can survive on 44s. It just requires a lighter foot.

I pulled some quotes from some different axle builders and prices are crazy. Cheapest option for a dana 44/60 axle set is $12k from Dynatrac. Currie was $14k for 60s f/r.

I’m with Kris and I think I will lean towards JK axles. But I have to talk with the CFO. 

Junkyard axles are tough for me. Lot’s of work and labor to shoehorn parts together to expect great road manners. It’s possible, but challenging. 

Ball joints seem to be bigger issues. d30, d44 jk44 all pretty much run the same ball joints. D60s are the beefier ball joints. I like 9 inch axles but they are pricey too plus low pinion unless you spend serious cash.

Um...what?

July 27, 2021
3:41 pm
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BKGM Jeepers
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Gregulator said
I’m kind of in the same boat as you Jeff. Build the 30/44 I have and stay on 35s or go bigger for 37s. I personally think 37s can survive on 44s. It just requires a lighter foot.

I pulled some quotes from some different axle builders and prices are crazy. Cheapest option for a dana 44/60 axle set is $12k from Dynatrac. Currie was $14k for 60s f/r.

I’m with Kris and I think I will lean towards JK axles. But I have to talk with the CFO. 

Junkyard axles are tough for me. Lot’s of work and labor to shoehorn parts together to expect great road manners. It’s possible, but challenging. 

Ball joints seem to be bigger issues. d30, d44 jk44 all pretty much run the same ball joints. D60s are the beefier ball joints. I like 9 inch axles but they are pricey too plus low pinion unless you spend serious cash.

  

Have you considered the used JKU D44 route?

July 27, 2021
8:02 pm
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Gregulator
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BKGM Jeepers said

Gregulator said

I’m kind of in the same boat as you Jeff. Build the 30/44 I have and stay on 35s or go bigger for 37s. I personally think 37s can survive on 44s. It just requires a lighter foot.

I pulled some quotes from some different axle builders and prices are crazy. Cheapest option for a dana 44/60 axle set is $12k from Dynatrac. Currie was $14k for 60s f/r.

I’m with Kris and I think I will lean towards JK axles. But I have to talk with the CFO. 

Junkyard axles are tough for me. Lot’s of work and labor to shoehorn parts together to expect great road manners. It’s possible, but challenging. 

Ball joints seem to be bigger issues. d30, d44 jk44 all pretty much run the same ball joints. D60s are the beefier ball joints. I like 9 inch axles but they are pricey too plus low pinion unless you spend serious cash.

  

Have you considered the used JKU D44 route?

  

I am considering the JK route. It seems the price of axles have gone up though. I priced out a front aftermarket complete jk Dana 44 with TJ brackets and it comes in around $5400. 

Um...what?

July 28, 2021
7:54 am
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BKGM Jeepers
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I paid 7200 for my front D60, about 8 years ago.  Is something like the 4wheelparts front D44 an option?  

July 28, 2021
11:48 am
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Gregulator
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It seems as though TJ parts are becoming more obsolete. G2 does not make a front TJ 60 anymore. Currie and Dynatrac are both considered “custom” orders to have a 60 built. Dynatrac doesn’t list any TJ axles on their website. Carbon Off Road will build TJ axles but only list dana 44s, jk width or tj width. 

The cheapest option I have seen but requires some welding is to buy straight from Genright. They stock 60s with no brackets for approximately $7800 for the front and $6100 for matching rear. But you get the specs they ordered.

https://genright.com/products/…..plete.html

In a perfect world, I would buy the Genright Currie front axle then build a junkyard 60 to match it. 

Um...what?

July 28, 2021
2:39 pm
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kris_olof
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Yeah Drew got the deal of the decade with his set of JKUR axles.  I will keep my eyes out though because I do see them pop up every so often.

Currently it looks like you can get a dana ultimate 44 for a JK for $3,632 with choice of gears and an e-locker and WITHOUT brackets or brakes/hubs/outer knuckles.

https://www.4wheelparts.com/p/…..28210554:s

Just add the Artech swap truss and source hubs/knuckles/brakes.

Once drew finishes his swap he will have a set of brakes, knuckles, and hubs available.  Additionally I have a jk44 30 spline rear sitting un-used.  Would still have to re-gear/lock/chromo the rear but that would knock out the front axle for around $4,500 with tax at MSRP.  Not sure if MC can beat 4-wheel parts prices on stuff like that.

 

As for the rear, there is a negligible price difference between 35 spline and 30 spline for the rear chromo axle shafts and ARB. Seems like a no-brainer to do both at once and get 35 spline rear.

July 28, 2021
3:08 pm
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kris_olof
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Gregulator said
 

Ball joints seem to be bigger issues. d30, d44 jk44 all pretty much run the same ball joints. D60s are the beefier ball joints. I like 9 inch axles but they are pricey too plus low pinion unless you spend serious cash.

  

Benefit to the JK set up over the TJ is the C is taller so 1350 joints fit and the increased space between the joints lessens the stress on the joints and the knuckle.  I have seen a few broken TJ knuckles but never a broken JK knuckle in person, just bent Cs. 

X2 on the 60 ball joints being beefier.  In the same way as the TJ to JK, the 05+ super duty 60 has increased space between the joints allowing for 1550 joints to fit over the smaller 1480 joints.  I went with a 99-04 set of outers since at the time currie was the only one who had parts in stock.  Should have waited since all but currie seemed to have upgraded to 1550 stuff

July 28, 2021
6:45 pm
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Guy and Lynda
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Have you noticed how quickly your money is spent without doing a thing? Not to mention how easy it is to spend somebody else’s money. It’s actually fun!

There were several great ideas kicked around, & for the price of a new Jeep, you can have yourself a well built, custom  Jeep, ready to go, of any generation. Gill has a capable TJ with 35’s & stays on the same trails as those with 37’s. I know, I’ve seen it.

No matter which configuration you go with, figure on having to rob the bank. 

July 29, 2021
7:42 am
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Jeff_R
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Thanks for all the great suggestions and advice. I have a below standard garage door height (the draftsman and engineer who modified my original blueprints never told me that before it was constructed, so I was stuck with it) so I don’t want to go any higher than 37’s and I don’t want to lift it more because I won’t be able to get it in the garage. I have considered building a detached garage on the other side of my property so unless and until then, I don’t want to lift my TJ more. If I do an axle swap, will it possibly increase the height of my Jeep more them my current set up? As it is, going to 37’s will be very tight with my hardtop on.

I didn’t realize that going from 35’s to 37’s was such a can of worms. At a minimum I may just go to beadlocks and new 35’s at some point in the future. Thanks again and keep the suggestions coming.

July 29, 2021
11:04 am
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kris_olof
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You can do a highline fender kit and fit them without any more lift.  Given that you are already long armed so it is really your front axle holding you back.  If the budget is scary you could run some wheel adapters on your existing rear for a year while you build a matching rear axle, only issue is that would stick you with 4.88s.

July 29, 2021
6:17 pm
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JohnDF
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Just increasing your axle size will lift your vehicle a bit higher because of the increased tube diameter.

I used to wheel a lot. . .

July 30, 2021
8:45 pm
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Folsom4Rnr (Brian)
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I

Specialsoundman said

JohnDF said

Going from 35s to 37s is a bigger jump than most people think it is… you’ll need much lower gearing to make it up Hwy 80, unless you’re okay with falling back with the Suzukis. grin

 

Thanks for mentioning us John, grinEveryone is welcome to join us.thumbs-up It’s always nice to have other running back with us.clap And as Brad has said our speed helps save gas. laughing

  

Im right there with yougrin

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