JK Wrangler Hot Rear Diff

[The Spook]

I have a 2009 2-door JK Wrangler and when I was changing the diff oils just recently I noticed that the paint was flaking off the rear diff. Thinking it might be heat related, I have checked it a few times after a long run on the freeway, and it gets that hot that I can't touch it for more that a second or so. I don't know the exact temperature, but I have ordered an infrared thermometer to check it out. I this normal? I don't tow anything and change the oil IAW the service schedule. I use dino 80W-90.

[Jimm]

This is normal my rear diff runs at around 65 deg Celsius. If you look on the American wrangler forum there is a lot of talk about diff temp including temp readings in Fahrenheit.

[wrangler2010]

Pretty normal. They do run hot.

[The Spook]

Originally Posted by Jimm

This is normal my rear diff runs at around 65 deg Celsius. If you look on the American wrangler forum there is a lot of talk about diff temp including temp readings in Fahrenheit.

Thanks Jimm. I checked out the USA Wrangler forums and got some pretty mixed info. Max running temps varied from 65 to 120 deg C. Recently I did a 350 km run on the Hume Hwy down around Yass and Gundagai and checked the temp of my rear diff a few times with an infrared thermometer. The temps ranged from 63 to 82 deg C, the latter coming after a quite a few hill climbs. Given that the ambient temp was 15 deg C at the time, that would mean that in summer the temp in my rear diff would rise to well over a 100 deg C. This seems a bit high to me. Does anyone else out there have any diff running temp data that they would like to share, or comment on if they think my diff temps are normal please?

[The Spook]

Further to my last, I have received the following from a Jeep dealership regarding Wrangler diff temps:

"Anywhere from 75-95 degrees is normal, 110 degrees is the upper limit and 120 degrees there is definitely a problem".

All temps in Celsius of course.

[Laz]

Originally Posted by The Spook

I have a 2009 2-door JK Wrangler and when I was changing the diff oils just recently I noticed that the paint was flaking off the rear diff. Thinking it might be heat related, I have checked it a few times after a long run on the freeway, and it gets that hot that I can't touch it for more that a second or so. I don't know the exact temperature, but I have ordered an infrared thermometer to check it out. I this normal? I don't tow anything and change the oil IAW the service schedule. I use dino 80W-90.

I think the problem is that you measured the temperature.....

I'd have no freakin idea how hot the diffs got in any of the cars I've driven.

[Fruju]

The diff hat is quite a smooth surface so the paint adhesion won't be that great. Mine started flaking after its first oil change as I had split the paint around the filler hole when tightening the nut.
The diffs will get hot which is a normal process with anything involving friction and movement.
Keeping the hot diff in mind it is a good idea to allow them to cool a little before attempting water crossings if one has been travelling at speed for some time beforehand.