Differential temps
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More Turbo
Joined: Feb 2003
Posts: 532
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From: Grand Rapids, MI
Differential temps
In light of the fact I recently finished my DIY eaton posi install and that the backlash is set a little on the tight side, I have been watching my rear diff temps. I typically use an IR thermometer and measure a few spots on the diff cover.
Today I hauled about 400lbs of scrap metal to the recycler followed by some around-town driving on the way back. Probably about an hour total driving time from my driveway to back.
Measuring the dif temps I saw a highest reading of about 120F degrees on the dif cover right over the ring gear area. Does anybody know what an expected temp would be? What would be considered "too high"?
Today I hauled about 400lbs of scrap metal to the recycler followed by some around-town driving on the way back. Probably about an hour total driving time from my driveway to back.
Measuring the dif temps I saw a highest reading of about 120F degrees on the dif cover right over the ring gear area. Does anybody know what an expected temp would be? What would be considered "too high"?
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Joined: Jul 2011
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From: Sioux Falls Area
Interested in what others say...
After a 10 minute cool down, the rear diff on my expedition was about 150f after hauling my ~7,000 lbs travel trailer. Like you I was measuring the temp with a rather inexpensive IR gun.
Not the best way to measure but good enough for a ballpark reading. I've got a better IR gun at work that you can change the emissivity setting for different materials, but I'm not sure how much difference it really makes.
After a 10 minute cool down, the rear diff on my expedition was about 150f after hauling my ~7,000 lbs travel trailer. Like you I was measuring the temp with a rather inexpensive IR gun.
Not the best way to measure but good enough for a ballpark reading. I've got a better IR gun at work that you can change the emissivity setting for different materials, but I'm not sure how much difference it really makes.
Laughing Gas
Joined: Mar 2003
Posts: 789
Likes: 7
From: Durham, NC
I've always heard 230 max at the top cover before the gears start to cook at contact??? I do know they can get so hot you can't touch the cover (or the hubs) bare handed and still be OK.
The gears of a rear differential are at a bad angle to start with. You're basically turning 90 degrees between ring and pinion. Considering gear angles, maybe more like 70-75 degrees? But still, that's got to cause some frictional heat even under normal driving.
Best advise is to change your rear fluids at 60,000 intervals and observe the internal magnet for metal. If no internal magnet, install one. And if the oil is mostly black before 60,000, it's getting hot. You can smell the gear oil as well and tell a lot. And if a set of gears get cooked, it's a good chance they will never mesh right again.
I just went through this with a Dana 80 rear end that was brought to me and ran too hot. It made a tremendous whining sound and a new rebuild kit (all new bearings) and new gear oil did absolutely nothing to fix the whining. And the backlash was still within tolerance. I bought a used dana 80 with warranty and installed it and kept the bearings for my next 80 rebuild (if ever).
The gears of a rear differential are at a bad angle to start with. You're basically turning 90 degrees between ring and pinion. Considering gear angles, maybe more like 70-75 degrees? But still, that's got to cause some frictional heat even under normal driving.
Best advise is to change your rear fluids at 60,000 intervals and observe the internal magnet for metal. If no internal magnet, install one. And if the oil is mostly black before 60,000, it's getting hot. You can smell the gear oil as well and tell a lot. And if a set of gears get cooked, it's a good chance they will never mesh right again.
I just went through this with a Dana 80 rear end that was brought to me and ran too hot. It made a tremendous whining sound and a new rebuild kit (all new bearings) and new gear oil did absolutely nothing to fix the whining. And the backlash was still within tolerance. I bought a used dana 80 with warranty and installed it and kept the bearings for my next 80 rebuild (if ever).
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