Rear axle temps

[Zandcwhite]

My guess is that it's a wash. The larger pinions have more contact, which could cause more energy to be created.

I think that "more contact" is over hyped just as much as the low gear pinion being "weak". If you look at the paint markings on a properly set up dif, the contact is pretty much the same. In reality only 1 set of teeth is contacting at a given time. Even if there's a slight difference in contact size I'd say it's negligible vs the much larger ring actually displacing oil capacity? Just a thought experiment for me, but we've run big tires on 2 JLs and a JT on stock gears for a total of 125k miles with 0 locker failures. Wheeled hard, driven hard, long road trips with the cruise set at 85mph for countless hours. Just a thought I had in what is different between Ted's use and mine? He also tows which would contribute to his heat issues? Knock on wood, somehow 39s aren't coming the locker electronics with 4.56s and I hope it stays that way.

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[zouch]

curious; did you ever happen to measure Dif Temps?
would be interested to know what your findings were.

(i measured mine on the cover with a handheld infrared thermometer when doing gear break-in after re-gearing just to make sure i was getting up to target temps during break-in.)

I bought and installed a Fusion semi float 60 in my Jeep. Fusion called for SAE 85w-140 gear oil. I asked the tech guy why they wanted this specific gear oil run. He stated the military had done extensive testing on diff fluids and that Lucas gear oil in 85w-140 ran the coolest of all fluids tested.

 

[Oletimer]

A new axle is going to get hotter than an axle that the gears have broke in properly. If you monitor and track the temperature over the same useage, you should see a definitive drop in temperature when the gears break-in. The aftermarket axle sellers often require you to change the oil after a break-in period. My axle shop said 500 miles.

Absolutely, again I compare apples to oranges and every other fruit.
But a new peterbuilt truck will start out with axle temps in rear drives at about 180 .
In about a month they will be down in 150 range at about two years they will be at 140.
That's running hours on end at probably 1000 pds of torque pulling a load.
The front drive axle does not pull unless locked but does rotate. Ironically they run about same temps.

 

[engineXI]

I checked the temp on my rear diff with Milwaukee Infrared temp gun, on the rear diff cover.

outside ambient temp ~70F
1) inside garage 69F (for the heck of it I ran it in the garage for 5 min, still 69F)
2) 1/4 mile: 78F
3) 6 miles: 112F
4) 15 miles: 144F (freeway driving - hit a max of 70mph)
5) 18 miles: 150F

150 feels hot, but actually not that hot (i think)

 

[CarbonSteel]

Here is a direct (submerged in the oil path) reading from my ISS Pro gauges:

https://www.jlwranglerforums.com/forum/threads/differential-oil-change.47318/post-2132038

Physically, the D44 ring gears are the same dimensions for all ratios so they do not contribute to a loss of fluid volume capacity. In addition, the argument about lower gear ratios being weaker is negated by the fact that Dana rates all gear ratios for the D44 Advanteks exactly the same on torque capacity.

Ergo, either they took the lowest torque rating and applied it across all ratios or all ratios can handle the same amount of torque.

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