Truck rear differential is too hot to touch.

[DonFitzwater]

I do believe that the second set of gears failed either by improper install or possibly a defective housing. I would bet that the housing is (was) defective. Did the rear end howl all the time, or when accelerating, or when decelerating?

This was my thought also. These axles aren't known for failure, much less repeated failures. A tech that is a parts swapping "hack" is a totally different story though.

 

[RustyJC]

Anyone that doesn't know how to (or just doesn't) check pinion bearing preload, backlash and tooth contact pattern has no business setting up a differential in the first place.

Rusty

 

[S.Morris]

Brand new gear sets (like your new install) need to have heat cycles to break in before heavy constant load is applied. 500 miles in one drive is not a proper break-in. Having the diff come up to operating temp and completely cool off to ambient is one cycle. I personally like to see several in 500 miles (and then an oil change).
YMMV. This is in a perfect world and I know that doesn't happen much, BUT , pulling a heavy 5th with a brand new diff is just asking for trouble.
I have at one time built heavy truck diffs for a living. They are a little bigger than our one tons, but the huge torque of these new engines really stresses the diffs if on heavy constant load.

I never measured, but would think that a lower gear ratio ie:4:10 will run hotter than a 3:42 (more teeth in mesh at one time with the 3:42 spreading contact load). The transmission will however have a heavier load on it with the 3.42.

 

[Too Tall]

I do believe that the second set of gears failed either by improper install or possibly a defective housing. I would bet that the housing is (was) defective. Did the rear end howl all the time, or when accelerating, or when decelerating?

All the time.

 

[Too Tall]

When I purchased my '13 RAM 3500 Crew Cab 4x4 DRW, I drove off the lot at 13 miles with about 2900 lbs behind it. Sure.....2900 lbs is no huge amount of weight, but towing right out of the box is not hard on these trucks IMO.
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When I purchased my '14 RAM 3500 Crew Cab 4x4 DRW, two days and 260 miles later, I had a 10k 40 ft GatorMade gooseneck trailer behind it going from Somerset, KY to Mt Pleasant, TX. Again......no problems.
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Maybe some have better luck than others....

I agree. Guys down hear in the hotshot business do the same thing. Drive them off the dealer lot and hook up to a trailer with 20K on it. No issues.