Aluminum Differential Cover Thermal Results

mike-s wrote:
That picture doesn't show what is implied. Put a piece of styrofoam or other insulation on the cover, and a picture of the outside will read an even lower temperature even if the internal temperature is unchanged. Aluminum is about a 4 times better thermal conductor than steel, but you also have to consider the thickness. I'll bet that aluminum casting is more than 4 times as thick as the steel original, so probably provides less cooling.

GordonThree is right, 10 degrees lower for both ambient and the same spot on the diff. The cover isn't making a difference.

The new aluminum cover is indeed much thicker than the stamped steel stock cover. That gives it more thermal mass and makes it slower to change temperature. Additionally, the aluminum cover is designed to hold 0.5 quarts more fluid, which also adds thermal mass.

I tried to control for these by taking the measurements after a good, long tow. After about an hour, I figure the temperature is at steady-state. Additionally, the larger thermal mass of the aluminum cover makes it equally slower to cool down, but I tried to keep those the same times as well.

I think it's helpful to look at the big chunk of iron near the axle tube. That should be a good place to compare the two configurations since it's the same for both. For the baseline case, that's showing "white" or around 199F. For the aluminum cover case, it shows "deep red" or 151F. (As a matter of chance, that spot was centered in the image and the exact temperature read-out was there).