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Just finally putting some miles on the car after restoration. 1970 dodge challenger t/a clone, i put a Dana60 from strange in it. I have a weird rubbing sound coming from the rear end when doing tight slow turns ( left and right). So i got home and jacked the back up to have a look and I notice the rear diff what super hot! couldnt even keep my hand on it for 2 seconds. I only went maybe 40 miles at highway speed. Is this normal to be that hot?

I am concerned because i want to take it for a long drive tmrw (6hr road trip) Should i be concerned?

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should be warm but not hot. New gear you have to drive a few miles then let it cool down a few times i thought

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I am also getting a funny noise from the rear end somewhere when making a tight L or R turn, perhaps the u-joints are binding up?

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With a Strange 60, lets assume 400HP at the FW, since 273's don't normally require them.

Most assume 20% drivetrain loss to the rear wheels.

Lets assume at highway speed you are using 100 HP average at the FW. That means you are "wasting" 20 hp thru the drivetrain and rear tires. If car is manual, I'd guess 5% (high?)loss there in tranny, and I'd guess 5% loss thru the rear tires. Lets assume no brake drag, and u joints zero drag ( ever felt a hot one?). That means 10hp is getting used up in Rear end. 1Hp equals approx 745 watts. That mean a big hunk of metal, with restricted air flow, fairly compact, is being heated internally by a mechanical heat source equal to 7450 watts.

Why would you expect to be able to put your hand and hold it on a piece of metal heated for an hour by a 7450 watt heater?

You can plug in any of your own numbers and likely get a different result, but I think I made my point.

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With a Strange 60, lets assume 400HP at the FW, since 273's don't normally require them.

Most assume 20% drivetrain loss to the rear wheels.

Lets assume at highway speed you are using 100 HP average at the FW. That means you are "wasting" 20 hp thru the drivetrain and rear tires. If car is manual, I'd guess 5% (high?)loss there in tranny, and I'd guess 5% loss thru the rear tires. Lets assume no brake drag, and u joints zero drag ( ever felt a hot one?). That means 10hp is getting used up in Rear end. 1Hp equals approx 745 watts. That mean a big hunk of metal, with restricted air flow, fairly compact, is being heated internally by a mechanical heat source equal to 7450 watts.

Why would you expect to be able to put your hand and hold it on a piece of metal heated for an hour by a 7450 watt heater?

You can plug in any of your own numbers and likely get a different result, but I think I made my point.

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Edit above assumes a properly operating rear end

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FWIW, '01 Durango with 8.25 rear (don't ask me why Chrysler did that) runs 120 degF in the winter and 140 degF in the summer. Sure-grip, 100K miles, aftermarket cast aluminum cover, and synthetic oil. Probe is through the cover. No towing.

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