How hot should the differentials be?

rancholago

rancholago

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I have Eaton true trac Limited Slip in the Dana 35 (rear) 3:72, Ox locker Dana 30 (front) 3:72. Installed each my self, paying close attention to the details of installation. Both differentials work how I expected them to, the Limited slip engages both wheels, the Ox Locker when locked works as I expected it to, and when not engaged, seems like normal open differential.
New fluids, no noise to speak of, no groaning, no grinding, no vibration or any thing out of the ordinary
First drive; about 10 miles, both differentials are very warm. I can hold my hand on them but they are pretty hot.
I dont think I have ever felt the temperature of the differential before, and am wondering how hot they are under normal operation.
Just trying to keep an eye on my install, double checking everything I can think of.
 
Jerry Bransford said:
Hot enough that you can't hold your hand on the pumpkin for more than a second or two.
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Here’s what may be a useful little trick that I learned as a refinery unit operator. If you can hold your hand on it then it’s less than 140 degrees. If you can just barely hold your hand on it, but have to remove it pretty quickly then it’s right at 140 degrees or slightly higher. This has been checked & proven with an infrared thermometer.
If there was something we thought might be too hot to touch we would spit on it & see if the spit turned to steam. ☺️
 
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Im guessing that after 10 + or - miles and at or about 140 degrees would be normal temperature for the differential, is there a spec for normal operating temperature for differentials? I am not worried about it being too hot, but now mostly curious if its something that could be watched if you suspect problems?
Mudflat thanks for that lesson on using your hand on the differential, I had heard that before.
 
Mudflat said:
Here’s what may be a useful little trick that I learned as a refinery unit operator. If you can hold your hand on it then it’s less than 140 degrees. If you can just barely hold your hand on it, but have to remove it pretty quickly then it’s right at 140 degrees or slightly higher. This has been checked & proven with an infrared thermometer.
If there was something we thought might be too hot to touch we would spit on it & see if the spit turned to steam. ☺️
Click to expand...
I like that. The specific temperature would be different for different materials (wood or plastic) but most hot things we want to know the temperatures of would be metal, so it's almost always going to be useful.
 
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Same ring and pinion, but installed the "trutrac" and the "ox" so ring was reinstalled and the backlash checked. Its got new carrier bearings and new seals.
It had 3:07 originally, I got different axles with 3:72 from a different Jeep and replaced both the front and rear axle assemblies, changing the carriers to the trutrac and ox, replacing carrier bearings, axle bearings, and seals.
 
rancholago said:
Same ring and pinion, but installed the "trutrac" and the "ox" so ring was reinstalled and the backlash checked. Its got new carrier bearings and new seals.
It had 3:07 originally, I got different axles with 3:72 from a different Jeep and replaced both the front and rear axle assemblies, changing the carriers to the trutrac and ox, replacing carrier bearings, axle bearings, and seals.
Click to expand...

just curious because I've considered installing my own front locker, but did you just check the lash or did you paint the teeth and check the contact pattern as well? is checking the pattern here necessary since the pinion depth wasn't touched?
 
I did check the pattern, but i really think that getting the lash right is the main thing. Ox says they build their carriers to the same specs as the original carriers and the same shims should work with the new carrier, but insure by checking the lash. In the Dana 30 i used bearings that I "ground out" so they slid over the carrier for fitting purposes. I actually had an extra set of new bearings I used to do the checking, but i was curious and got the same measurements with using the bearings I removed from the original carrier. So Im not so sure that buying new bearings is an absolute.
 
rancholago said:
I did check the pattern, but i really think that getting the lash right is the main thing. Ox says they build their carriers to the same specs as the original carriers and the same shims should work with the new carrier, but insure by checking the lash. In the Dana 30 i used bearings that I "ground out" so they slid over the carrier for fitting purposes. I actually had an extra set of new bearings I used to do the checking, but i was curious and got the same measurements with using the bearings I removed from the original carrier. So Im not so sure that buying new bearings is an absolute.
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Cool. That seems to make sense to me, because the pattern is determined by both the pinion depth and the lash, that if the pinion wasn't touched then the same lash should have the same pattern.

I wouldn't put to much stock in what they said about using the same shims. All specs have a tolerance so if your carrier was at one end and the ox was at the other, they'll be the same spec and still need different shims to get the ring gear in the right spot. It's good you went ahead and checked.

It sounds like you're probably in good shape.
 
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