Differential Temperature

[mburger]

Hello
My gears are 3.55 with a 347 driven usually like a grocery getter.
I was under the car after a normal drive in traffic and touched the pumpkin.
I was surprised how hot it was. Granted, sliding under the car right after a drive isn’t something I normally do.
After a drive the next day, I hit the differential and axle tubes with a temperature gun.
Is 140 at the gears and 110 on the axle tubes high? It certainly felt warmer to my hands than the reading on the temperature gun. I am not having any issues except for a very slight whine when I hit 55 in any gear. Before the car’s complete rebuild it was much much louder. The differential oil was changed which may account for it being quieter now.

[toadster]

I'd say you're totally fine, well within range https://www.streetmusclemag.com/tech-stories/fuel-cooling-ignition-tech/tempurature-check-ffr-cobra-challenge-gets-diff-trans-coolers/

“A good operating range is generally considered to be around 180-220 degrees, but a manufacturer might expect as much 250-260 degrees in racing context,”

[J R Jones]

Mburg, years ago we did back to back tests of differential heat on a USAC stock car (Ford 9") with mineral and synthetic lube. Synthetic dropped the temperature almost 20 degrees.
toadster is right, 200 degree oil is OK. Don't touch that!

[mburger]

I won’t touch it! Lol
Thanks guys. Much appreciated!

[tonywy]

I just did a gear change on my car from 3.08 to 3.73 and very happy with the change. I did the same thing you did after the first three break in cycles. I couldn't keep my hand on the differential for more tha a few seconds so, I checked the temp, 160 at the pinion and 150 on the diff cover all three times. So I did some research and discovered this is normal. I never realized a differential gets that hot.

[mburger]

I just did a gear change on my car from 3.08 to 3.73 and very happy with the change. I did the same thing you did after the first three break in cycles. I couldn't keep my hand on the differential for more tha a few seconds so, I checked the temp, 160 at the pinion and 150 on the diff cover all three times. So I did some research and discovered this is normal. I never realized a differential gets that hot.

Exactly! I’m well aware they can get hot when racing, and there are coolers for that, but I was surprised it was that hot under “normal” driving conditions.