Upgrading axles: Why is upgrading the rear more important than the front?

Chocolate Thunder

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New to upgrading axles. Why is strengthening the rear more important than the front? Is it ok to upgrade them separately as long as the ratios are the same?





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I'm not exactly sure why the rear should be stronger than the front. Maybe it's because more of the Jeeps weight is on the rear axle when you're going uphill? You definitely can upgrade one at a time. Many Jeeps come stock with differently sized axles front to rear. And yes, the ring and pinion gear ratios have to be the same if you want all of your tires to spin at the same rate in 4wd. It's for the same reason that you wouldn't put 40" tires in the back and 35's up front.
 

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New to upgrading axles. Why is strengthening the rear more important than the front? Is it ok to upgrade them separately as long as the ratios are the same?
Its not - generally the front is the weak point (being a dana 30 for many)

Its fine to do one at a time, but you need to make sure your widths are the same. Also, if you are going 60's, bolt patterns change for the rims (full float rear). I think you can still get 5x5 on a semi float 60.


If you go tons, i would recommend doing both in one go. Other wise a Pro rock 44 in the front and the stock 44 in the rear are fine for most
 

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Maybe due to more wear and tear on the rear being that it is engaged much more often than the front? I will say I've seen far more broken front axles on trails than rear, although I have seen a couple.
 

harleypap57

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New to upgrading axles. Why is strengthening the rear more important than the front? Is it ok to upgrade them separately as long as the ratios are the same?
I have a 2018 Sahara JLU. I upgraded my front axle first (March 2019) since it seems to take the most punishment when going off-road. I have a Dana Ultimate 44 Axle with 4.88 gears. I did change to rear 200 axle to 4.88 gears at that time. Recently (Aug 2019) I put a new Mopar Rubicon 44 / 220 rear axle in with the 4.88 gears also. Both now have E-Lockers.
 

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I swapped my front M186 out for a locker equiped PR44. My rear M220 is stock (except for 4.56 gears).
I’ve been wheeling for 15 years (mostly TJRs) and all of my issues have been with the front axle.
 
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Can the factory electronic lockers be retained when upgrading to stronger axles?
 

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Can the factory electronic lockers be retained when upgrading to stronger axles?
I'm curious if the factory AUX/Locker switches work with aftermarket elockers/Axels that come with elockers. Thinking that I'll be swapping the M186 out for a M220/Dana 44.

Also, can you get 4.10 gears for the rear M200?
 

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I'm curious if the factory AUX/Locker switches work with aftermarket elockers/Axels that come with elockers. Thinking that I'll be swapping the M186 out for a M220/Dana 44.

Also, can you get 4.10 gears for the rear M200?
I had mine wired to the factory Aux switches before I put in an sPOD. Everything now runs through it. I had 4.88 gears in my stock Sahara 200 axle before I replaced it with a Rubicon rear. I wanted a stronger axle and lockers in the rear.
 

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I had mine wired to the factory Aux switches before I put in an sPOD. Everything now runs through it. I had 4.88 gears in my stock Sahara 200 axle before I replaced it with a Rubicon rear. I wanted a stronger axle and lockers in the rear.
Thanks, I just went and looked at my local Jeeps parts company. Sure enough, they have regearing kits for the D30/M185 and D35/M200. I may pick some up. I miss having 8th on the highway. Since I swapped up to 275/70/18s on my Sahara I rarely see 8th when doing 70MPH.
 
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Chocolate Thunder

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I had mine wired to the factory Aux switches before I put in an sPOD. Everything now runs through it. I had 4.88 gears in my stock Sahara 200 axle before I replaced it with a Rubicon rear. I wanted a stronger axle and lockers in the rear.
Are the OEM electronic lockers and dash switch compatible only with Mopar OEM axles, or with aftermarket axles as well? Could I use say a Dynatrac axle and retain factory locker and switch?
 

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Can the factory electronic lockers be retained when upgrading to stronger axles?
The only aftermarket housing that can utilize the OEM JL lockers is the mopar UD44 front axle, and I don't believe you can purchase just the housing.

You'll want a strong rear axle because it does most of the heavy lifting. Most of the ring and pinion failures I've seen have been rear axles. When your front axle is supporting the weight of the vehicle you're generally pointed downhill and will have gravity assisting you. When your rear axle is supporting the weight of the vehicle you often have gravity working against you. And on the front end you'll usually break u joints before the ring and pinion especially if you have some steering angle applied. The rear doesn't really have a "weak link" like that.

With that said I would feel comfortable wheeling with 35s on stock axles. I'd keep the gear ratio to 4.56 or higher (numerically lower) for better gear mesh unless you have a manual. For 37s, something like a UD44 or PR44 would be fine in the front, but I would want a full float rear with a larger gear set.

You can upgrade your axles separately and run mis-matched gear ratios as long as you never engage 4wd.
 

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