Went from 410s to 513s 800 miles ago and just changed the differential fluid. Everything looks ok but I noticed that the rear diff was very hot to the touch. I checked it with an IR thermometer and the ARB diff cover is reading 140 degrees F. The ambient temp is 65. The front diff is showing 100 degrees F. This is after driving approx 10 miles at 45mph.

Does this seem too warm for the rear diff?

Thanks

 

That doesn't seem too high at all. I know on mine, (stock 4.10 gears), sometimes it's almost too hot to leave my hand on the cover, especially in the area of the pinion housing.

Have you checked the wear pattern on the new gears yet?

 

Ok thanks, wear pattern is tough to see at 800 miles, for my untrained eye anyway but from what I could make out, it looks ok.

 

That is about right. One would not think they get hot, but there is a lot of friction in there.