Rear End Temperature

[Stumper]

I don’t think I have ever put my hand on a rear end immediately after driving some to feel the temperature. Took the 62 out for a cruise the other day, about 20 miles round trip. When I got home i immediately drove up on the lift to check that my speedometer pinion repair wasn’t leaking. I checked the rear end while I was there since I recently replaced the pinion seal and bearing and it was also dry - but I was surprised at how warm the housing was. Any idea what would be normal temperature for the input housing on a 742 case?

 

[440 Charger]

I don’t think I have ever put my hand on a rear end immediately after driving some to feel the temperature. Took the 62 out for a cruise the other day, about 20 miles round trip. When I got home i immediately drove up on the lift to check that my speedometer pinion repair wasn’t leaking. I checked the rear end while I was there since I recently replaced the pinion seal and bearing and it was also dry - but I was surprised at how warm the housing was. Any idea what would be normal temperature for the input housing on a 742 case?

Its probly alot more than you think.

 

[493 Mike]

Its probly alot more than you think.

But less than a 9" Ford. Chrysler's design is a more friction free design!
Mike

 

[MoparLeo]

Also temp depends on whether it is a Sure-grip or not. The Sure-grip will run hotter.

 

[themechanic]

My rear end is about 98.6 degrees.

 

[RGC440]

My rear end is about 98.6 degrees.

Too Much Info! The mental picture of verification is disgusting.

 

[khryslerkid]

Using a infrared gun I've seen 120* to 145*. Depending on outside temps and what kind of load that's being placed on it.

(Referring to a 8 3/4 rear, not a human being)

 

[IQ52]

Too hot to leave you hand on it for very long. Depending upon the load........140-200 degrees.

 

[hunt2elk]

I was shocked as well a couple years ago after doing the same as you. I had a new Strange 60 from Cass. I can't remember exactly what my temp gun showed, but I think it was 140. I called Cass and he put my mind at ease saying that was perfectly normal.

 

[dadsbee]

I have my numbers written down in the shop, will try to remember to find them tomorrow. Took them when I was fighting a hot front spindle on the Bee and I also did the Bird. Both run damn near identical for rear axle and all hubs.

 

[Stumper]

Mine does have a sure grip and my 1/4 mile driveway is steep and full of curves. It was uncomfortable keeping my hand on it for sure.
My first thought was that the new pinion bearing was heating up too much but I guess even 125 degrees is uncomfortable to the touch.

 

[MelroseMopar]

This is awesome information! I have also inadvertently touched my differential and was surprised at how warm it was and wondered if it was normal I checked fluid level and it was good and looked ok so i left it but wondered..

 

[451Mopar]

Looking at viscosity specs on Redline diff oil, they spec 40C (104 F), and 100C (212 F)

Some white paper that might be informative?
https://www.redlineoil.com/Content/files/tech/Gear_Oil_Tech_6.20_.pdf

 

[dadsbee]

After 2 hour cruises....

'69 Bee with drums all around:
Side of pumpkin = 165/170F (2.94/1 x 741 suregrip clutch)
Bottom of pumpkin = 145F
Rear axle tube = 111F
Rear wheel hub - Left = 105F Right = 104F
Front hubs - Left = 90/94F Right = 94/98F
Lower Radiator hose 165/175F
Upper Radiator hose 220F

'70 SuperBird with front discs:
Side of pumpkin = 165F (3.55/1 x 489 presumably cone - never been apart)
Bottom of pumpkin = 150F
Rear axle tube = 120F
Rear wheel hubs - Left = 115F Right = 112F
Front hubs at wheel face - Left = 119F Right = 121F
Lower radiator hose = 170F
Upper radiator hose = 225F
Power steering pump = 190F

 

[DeltaV]

This is consistent with what I've heard in the past during safety courses:

The National Institute for Standards and Technology says human skin begins to feel pain at a temperature of 111 degrees (think hot bathwater). At 118 degrees, human skin can sustain first-degree burns; a second-degree burn injury can occur at a temperature of 131 degrees. Human skin is destroyed when temperatures reach 162 degrees.

Source:
https://whnt.com/weather/valleywx-blog/pavement-hot-enough-to-cause-second-degree-burn-injury/

 

[Stumper]

Great info Dadsbee! Thanks for posting actual data. I feel a lot better about my rear end (cars) after the feedback in this post. Thanks everyone!

 

[Cranky]

Also temp depends on whether it is a Sure-grip or not. The Sure-grip will run hotter.

Don't know why a Sure-Grip would run hotter unless it's slipping.....

My rear end is about 98.6 degrees.

TMI! lol

Too hot to leave you hand on it for very long. Depending upon the load........140-200 degrees.

Got 200 on my pickup after a long haul pulling 5000 lbs years ago....and you're right. You can touch high temps but not for long! Used to check bearing houses on pumps in the refinery by hand to see how hot they were before actually using a probe. That was when I was doing 'safety' analysis which was a very cushy job. Cool ones got pencil whipped but it didn't take long to feel the ones that were running too hot! Problem equipment was easily found and usually could be spotted before 'laying on the hands'

 

[themechanic]

After 2 hour cruises....

'69 Bee with drums all around:
Side of pumpkin = 165/170F (2.94/1 x 741 suregrip clutch)
Bottom of pumpkin = 145F
Rear axle tube = 111F
Rear wheel hub - Left = 105F Right = 104F
Front hubs - Left = 90/94F Right = 94/98F
Lower Radiator hose 165/175F
Upper Radiator hose 220F

'70 SuperBird with front discs:
Side of pumpkin = 165F (3.55/1 x 489 presumably cone - never been apart)
Bottom of pumpkin = 150F
Rear axle tube = 120F
Rear wheel hubs - Left = 115F Right = 112F
Front hubs at wheel face - Left = 119F Right = 121F
Lower radiator hose = 170F
Upper radiator hose = 225F
Power steering pump = 190F

Operator-98.6F

 

[DeltaV]

Medical research hasn't determined an exact correlation between oral, rectal, ear, armpit, and forehead temperature measurements. Generally, the correlation of temperature results are as follows:

• The average normal oral temperature is 98.6°F (37°C).
• A rectal temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature.
• An ear (tympanic) temperature is 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral temperature.
• An armpit (axillary) temperature is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.
• A forehead (temporal) scanner is usually 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature.

Source:
https://www.uofmhealth.org/health-library/tw9223

 

[AR67GTX]

Amazing how hot they get. I ran mine sitting on jackstands for awhile to check out rear end noise. After awhile I put my hand on it and it was really hot. Didn’t check it with an IR gun though.