Re-gear or new axles

[JHTrail]

I’ve appreciated reading the experiences of everyone on the Forum. I’m now glad to be part of the group. Questions: I have a 2023 Diesel JLUR, running 37s, 2.5” lift, on stock D44s. I am considering either re-gearing to 4.56, or biting the bullet and installing D60s with 4.56.

1. I’m really concerned with trusting dealership to re-gear. My experience over the years has not been good. Thoughts on dealership vs specialty shop?

2. I don’t see going larger than 37s in the future. My rig is a daily and very often on the rocks or trails. It seems 4.56 will get me closer to OE spec, but would you do 4.88 just in case you go larger in the future?

3. The D60s add more capability off-road. If I stay with the D44s and re-gear, I’ll likely upgrade to better axle shafts.

Thoughts?

Thanks all!

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[tecnic1]

If you're staying with 37s, I would just regear the 44s. A 44 should be strong enough for 37s, and a 60 is going to cost you ground clearance.

I found a specialty shop to do my regear. I'm guessing they probably do more regears than the dealership. Your best bet would be to find a local axle shop, and if you can't find one of those, an off road shop.

4.56/4.88 is personal preference. I went 5.13, but I'm not a diesel.

 

[DonH63]

Regearing through a off-road or performance shop is what I would do. They see gear swaps all the time vs. maybe one guy at the dealer who does one now and then. Regearing is much cheaper than full swaps, at least at my local shop, and they can replace the shafts while they are in there. Swapping to 60's means replacing a lot of other components as well. A 60 is much stronger, but much bigger (e.g. less ground clearance as @tecnic1 said) and heavier, so the trade and whether you need that depends upon your driving habits and such.

4.88's will give you more get-up-and-go and help off-road at the cost of on-road mileage. A diesel has good low-rpm torque so 4.56's may be a good choice to improve off-roading without affecting on-road performance. I've gone both ways in the past (on different vehicles), starting with 4.88's which gave a nice performance kick but ultimately staying close to stock ratios since like you my vehicle was a daily driver spending most of its time on roads (sigh). If you do a lot of wheeling, 4.88's might be a better choice. Wishy-washy I is, yes, sorry...

 

[mnjeeper]

I'm planning to regear, but I hate the idea of that, then probably RCVs and rear alloys, trusses maybe, rebuildable balljoints, etc...then looking back and realizing all that and the sale of stock would have gotten me well on the way to 60s. I guess I will jump off that bridge when the time comes.

 

[Mojave Dust]

Why are you wanting to re-gear a diesel? Gasser have to re-gear, but you have twice the torque. I run 37's and am pushing 6100 lbs with stock 373 gearing in my diesel and can run 80 mph in 8th gear consistently. I also off-road pretty hard with no issue. Are you not seeing the same performance?
You might consider upgrading the steering components and replacing the aluminum knuckles, better ball joints, etc. for a better investment. If you go with 40's later, for sure consider a re-gear, but you'll appreciate the upgraded steering in that case as well.

 

[grimmjeeper]

I have a diesel and I'm running 37s with no regear. It does fine with 3.73s. Optimal gears for 37s is 4.10 in my opinion but it's not worth doing the swap from 3.73. I loved the 3.73 gears with 35s.

Personally I would try the 37s before regearing and see how you like it.

I have a truss, RCV shafts, and Reid knuckles in the front. The rear is getting a truss as soon as the new rear shafts arrive. That will make the axles strong enough for what I do which is 98% daily driving and road trips with 2% on difficult off road trails.

 

[AcesandEights]

If I was deciding between re-gear or axles, and based on what you've posted about your driving on-road and off, I'd buy a motorcycle.

 

[JHTrail]

You are all great - thank you. Let me try to answer some of your questions, as many of them are the same questions I’ve been wrestling with. First, seems all are in agreement (if I was to re-gear) to find a specialty shop. I was leaning that direction and guess I deal with warranty issues in the future if they arise. Second, I’ve been thinking about waiting and seeing how the old girl holds up, but I have experienced a notable drop in highway performance driving up-grade. I live in the mountains and drive my jlur daily, so I’m expecting a re-gear to help me on the inclines. As is, I’m often dropping into 5th, 6th, or 7th just to maintain or increase speed. Out on the rocks or trails I’m experiencing no issue with torque/performance. Third, everything I read about 37s on the jlur diesel is that re-gearing will provide better resistance to the increased torque on the wheels, especially if making a technical turn out of a tight rut on the rocks. I could wait and see if that’s unnecessary, but it would be an awful place to find out I was wrong. And I guess that’s the primary driver for thinking about doing the work sooner than later - avoiding a break-down on the trails. Secondary thought is recouping power at altitude, driving up-grade.

 

[JHTrail]

If I was deciding between re-gear or axles, and based on what you've posted about your driving on-road and off, I'd buy a motorcycle.

Wouldn’t mind adding that to the toy box, but alas I don’t have complete say about what goes on that box….

 

[sciotola88]

100% you're going to want to re-gear if you live up in the mountains. I would go with 4.56 gears and call it a day. Your rubi axles are plenty strong enough for 37s. I find that when I'm going 60-65 i tend to downshift more on inclines due to the lower RPMs.. when I'm going 70-75 i can take steeper inclines but will inevitably downshift to 7th to make it up it. I'm also running a GDE tune.

 

[DonH63]

Just noticed you are also in CO. A mile high, more or less, you lose about 15% in HP from what I recall. My house is even higher (~7500') and I lose about 22.5%. So yeah, regearing should help.

Edit: Online calculator http://www.wallaceracing.com/braking-hp.php -- I enter altitude and 100 HP to make it easy to see the percentage lost.

 

[zouch]

i did 37s on my Diesel and later re-geared to 4.56s; everything works much better now.

it's not just about the available torque; the engine and transmission are designed with the expectation that they will be turning at certain RPMs and have a certain Oil and Coolant flow at any given speed/load, and i play too much in the Dez to want to be messing with that.
bonus is that the (awesome) 8HP75 seems much happier shifting on the trail in 4LO after re-gearing.

4.56s take you a tiny bit deeper than stock already, which works out nicely for me on and off pavement. mathematically you could go all the way to 39s on 4.56s and still be geared deeper than we were with 3.73s, but i wanted to stay on the deeper side to make up for increased weight and wind load from lift and larger tires spinning in the wind.

 

[Old Jeeper]

I’ve appreciated reading the experiences of everyone on the Forum. I’m now glad to be part of the group. Questions: I have a 2023 Diesel JLUR, running 37s, 2.5” lift, on stock D44s. I am considering either re-gearing to 4.56, or biting the bullet and installing D60s with 4.56.

1. I’m really concerned with trusting dealership to re-gear. My experience over the years has not been good. Thoughts on dealership vs specialty shop?

2. I don’t see going larger than 37s in the future. My rig is a daily and very often on the rocks or trails. It seems 4.56 will get me closer to OE spec, but would you do 4.88 just in case you go larger in the future?

3. The D60s add more capability off-road. If I stay with the D44s and re-gear, I’ll likely upgrade to better axle shafts.

Thoughts?

Thanks all!

If you are spending time in Moab, which I bet you are, then I would go Dynatrac Pro Rock 60s, which are high pinion and prob has better clearance than the D 44.

You may want to consider 4:88s, if you have the 8 sp or even the manual 6, you have lots of room at the top for Hwy use. I have run 4:88 since 2003 and got them in my JLR now and on my JLR I have on order.

 

[grimmjeeper]

If you are spending time in Moab, which I bet you are, then I would go Dynatrac Pro Rock 60s, which are high pinion and prob has better clearance than the D 44.

You may want to consider 4:88s, if you have the 8 sp or even the manual 6, you have lots of room at the top for Hwy use. I have run 4:88 since 2003 and got them in my JLR now and on my JLR I have on order.

He has a diesel. 4.88s are way too much gear for that engine.

For a gasser, I'd do 4.88 or 5.13s. For a diesel, 4.10s or 4.56 are better. For 37s anyway.

 

[Old Jeeper]

He has a diesel. 4.88s are way too much gear for that engine.

For a gasser, I'd do 4.88 or 5.13s. For a diesel, 4.10s or 4.56 are better. For 37s anyway.

Well he is having some issues with torque and power, and dropping back down into the gears. He is struggling now on 37s.

The 8 sp aut trans, has 2 over drives. Wondering if he struggling to get into the top of is trans gears I would lean towards 4:88.

Tough call to make. Nothing wrong with going 4:56

He did not say what his current ratio is unless I missed it. If he is driving in 4th gear to get there then 4:88s would help, if he is living in 5th gear, 4:56 could be the sweet spot...what do you thnk?

• 1st - 4.71
• 2nd - 3.13
• 3rd - 2.10
• 4th - 1.67
• 5th - 1.28
• 6th - 1.00
• 7th - 0.84
• 8th - 0.67

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