Rear diff cover with increased fluid capacity

[flick2614]

Reading up on rear locker/gear failures has me looking for a rear diff cover with more fluid capacity to minimize heat related failures. Looking at all the different options though and no one really calls out the capacity of their covers.

Any suggestions on a rear diff cover with a confirmed increase in fluid capacity? Bonus points if it's finned to dissipate more heat.

2021 JLU Rubicon Diesel.

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[Andy392]

I prefer the afe aluminum cover part 46 71000, more oil content, finned and much better thermal conductivity than steel.Regards from Austria

 

[GATORB8]

Might want to carry an extra cover and lube if you run an aluminum finned cover on trail.

 

[azwjowner]

Also remember the easiest way to reduce heat in the gears is to drive slightly slower. As a benefit, you save gas, have less noise, better handling, etc.

https://www.jlwranglerforums.com/forum/threads/diff-fluid-wrangler-jl.97387/post-2023564

I installed ISS Pro axle temperature gauges shortly after buying my JL. The rear axle temperature is is typically 210°F while running unloaded down the highway at 70MPH in 85°F ambient temperatures. I have seen it hit 230°F under the same conditions but going 80MPH.

 

[MarkM]

I used the Dana covers front and rear. They are iron, have a fin pattern and the OEM should know the best way to manage internal fluid dynamics, IE. how to "walk" fluid to the pinion bearing. They also have two fill holes if you need to compensate for axle rotation on a lifted rig that changes the fill hole location. They hold about 3/4 quart more fluid as well.

https://spicerparts.com/parts/axle/...e/spicer-nodular-iron-performance-diff-covers

I like the idea of aluminum, but I see a ton of flat covers that don't 'wrap' the ring gear and can cause more turbulent fluid movement.

Just using a simple measurement after driving a loop on the highway and with 75w-140 oil, the rear axle is about 10 degrees cooler after getting off the interstate. I was curious about viscosity breakdown from thermal issues in the long run. After 7 minutes of county road driving to home, the temp was 170-175 versus 180-190 on the factory covers.

I'm a couple miles from I-25 and it was 80 degrees on the handful of days I tried checking before and after installing the heavier covers.

It obviously isn't a scientific evaluation, but it was consistent and any little change can't hurt.

 

[chevymitchell]

Reading up on rear locker/gear failures has me looking for a rear diff cover with more fluid capacity to minimize heat related failures. Looking at all the different options though and no one really calls out the capacity of their covers.

Any suggestions on a rear diff cover with a confirmed increase in fluid capacity? Bonus points if it's finned to dissipate more heat.

2021 JLU Rubicon Diesel.

More fluid doesn't do anything for heat.

The fluid will get heat saturated whether you're using 2 quarts or 2 gallons, it would just take slightly longer to reach heat saturation.

Finned covers would help more than more fluid.

The only way a diff would reach a temperature that would cause damage is low fluid, bad/contaminated fluid, towing beyond spec, or bad parts/set-up (bad bearing, tight preload, backlash, etc...).

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