Diff fluid - Wrangler JL

[CarbonSteel]

Do we know how hot these things are running? They seem to be sized like most other vehicles. I recall running oil coolers on road race car diffs way back. Are we having temps needing a cooler?

I installed ISS Pro axle temperature gauges shortly after buying my JL. The rear axle temperature is is typically 210°F while running unloaded down the highway at 70MPH in 85°F ambient temperatures. I have seen it hit 230°F under the same conditions but going 80MPH. At 110°F ambient and 70MPH, I have seen 235°F. Loaded running fast will have the temperatures hitting 240°F.

Compare that to my 2010 F-150 with a 9.75" gear that rarely hit 200°F unloaded and my 2015 F-250 Powerstroke with a 10.5" ring gear that rarely hit 190°F and you can see the difference.

For clarity, an M220 rear JL axle has a 8.66" ring gear.

EDIT - forgot the photo (75MPH @95°F ambient--4.10 gears and 35" tires--unloaded):

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[mushroomax]

Do we know how hot these things are running? They seem to be sized like most other vehicles. I recall running oil coolers on road race car diffs way back. Are we having temps needing a cooler?

Yeah, after swapping out a set of 4.10s for 4.88s I'd hit the rear diff with a thermal gun every now and then. I think the highest temp I saw was 207F. Everything is in spec. After break-in I stopped checking once I saw it come down to 170F, IIRC that was with 5k on the new gear set. In my opinion 170 is still at the higher end of the spectrum, sent Dana Spicer an email about it, think I lost that reply to the junk folder...

Tons of info out there about diff temps, just don't know what normal is for these Advantek D44s

 

[mushroomax]

I installed ISS Pro axle temperature gauges shortly after buying my JL. The rear axle temperature is is typically 210°F while running unloaded down the highway at 70MPH in 85°F ambient temperatures. I have seen it hit 230°F under the same conditions but going 80MPH. At 110°F ambient and 70MPH, I have seen 235°F. Loaded running fast will have the temperatures hitting 240°F.

Compare that to my 2010 F-150 with a 9.75" gear that rarely hit 200°F unloaded and my 2015 F-250 Powerstroke with a 10.5" ring gear that rarely hit 190°F and you can see the difference.

For clarity, an M220 rear JL axle has a 8.66" ring gear.

EDIT - forgot the photo (75MPH @95°F ambient--4.10 gears and 35" tires--unloaded):

Holy shit, I didn't know they ran that hot. I wonder what DANA would say the normal operating temp range is

 

[roaniecowpony]

Any data on gear oil life vs temperature? I would think we're ok in the low 200s, but as we get closer to mid 200s life would be exponentially shorter.

 

[grimmjeeper]

So all this discussion about temps is interesting and all.

Are there any failures due to operating at these temperatures? Is there any actual documented evidence of excessive wear on anything?

I know I've asked this a few times but no one actually gives me an answer.

 

[mushroomax]

Failures? Probably not. Excessive wear over the lifespan of internal components? Probably
Am I speculating? Yes
Can I provide proof? No

 

[CarbonSteel]

So all this discussion about temps is interesting and all.

Are there any failures due to operating at these temperatures? Is there any actual documented evidence of excessive wear on anything?

I know I've asked this a few times but no one actually gives me an answer.

And I doubt that you will get one either since that data is hard to come by and would take 1000s of data points to perform a trend analysis to try and determine anything. The other variable is that some of us have re-geared (a few multiple times) and therefore you are changing the baseline every time that you change gears and bearings.

With that said, I think the question that should be asked is what is gained by running a thicker viscosity? The data that I have gathered thus far tells me that using a thicker viscosity will:

1. Combat the higher temperatures by not losing as much viscosity as a thinner oil at the same temperatures
2. Increase the oil life as it will not break down as fast as a thinner oil
3. Potentially increase service life due to the reduction of wear

 

[CarbonSteel]

Any data on gear oil life vs temperature? I would think we're ok in the low 200s, but as we get closer to mid 200s life would be exponentially shorter.

Here is a pretty good read on it from Shell - https://www.shell.us/business-custo...filet/effect-of-temperature-on-viscosity.html

There is a PDF in the article (https://www.shell.us/business-custo...ect-of-temperature-on-lubricant-viscosity.pdf) that has this table in it (though their °C to °F conversions appear to be off on the 325°F and 107°C cell)--it should be 225°F and 107°C):

 

[CarbonSteel]

Holy shit, I didn't know they ran that hot. I wonder what DANA would say the normal operating temp range is

I am betting that Dana would say two things:

1. FCA - stop reducing the oil capacity in our axles.
2. FCA - stop telling Jeep owners to deviate from the 75W-140 that we recommend.

 

[CarbonSteel]

Yeah, after swapping out a set of 4.10s for 4.88s I'd hit the rear diff with a thermal gun every now and then. I think the highest temp I saw was 207F. Everything is in spec. After break-in I stopped checking once I saw it come down to 170F, IIRC that was with 5k on the new gear set. In my opinion 170 is still at the higher end of the spectrum, sent Dana Spicer an email about it, think I lost that reply to the junk folder...

Tons of info out there about diff temps, just don't know what normal is for these Advantek D44s

The problem with checking the housing is that it is much removed from the actual temperatures. Even my probes which are submersed in the oil path when the axle is turning is not giving me the hottest temperature the axle is seeing. I would have to drill and tap the area right behind the pinion gear to grab that number, but for obvious reasons, I did not do that.

 

[mushroomax]

Ur splittn hairs now brutato

 

[CarbonSteel]

Ur splittn hairs now brutato

Just depends on how accurate you want to be. ? Infrared guns are notorious for not being very accurate, that is why I chose to install temperature gauges into the oil stream.

 

[grimmjeeper]

And I doubt that you will get one either since that data is hard to come by and would take 1000s of data points to perform a trend analysis to try and determine anything. The other variable is that some of us have re-geared (a few multiple times) and therefore you are changing the baseline every time that you change gears and bearings.

With that said, I think the question that should be asked is what is gained by running a thicker viscosity? The data that I have gathered thus far tells me that using a thicker viscosity will:

1. Combat the higher temperatures by not losing as much viscosity as a thinner oil at the same temperatures
2. Increase the oil life as it will not break down as fast as a thinner oil
3. Potentially increase service life due to the reduction of wear

Are you trying to talk me into something or are you just trying to justify your own decisions?

I have no interest in convincing you of anything. I'm just trying to get more information.

 

[CarbonSteel]

Are you trying to talk me into something or are you just trying to justify your own decisions?

I have no interest in convincing you of anything. I'm just trying to get more information.

Neither. My point is you will be hard pressed to find the data you are seeking therefore, you can either accept FCA's recommendations (75W-90) or Dana's (75W-140).

One is totally based upon CAFE and the other is based upon longevity.

 

[grimmjeeper]

Neither. My point is you will be hard pressed to find the data you are seeking therefore, you can either accept FCA's recommendations (75W-90) or Dana's (75W-140).

One is totally based upon CAFE and the other is based upon longevity.

You certainly are persistent in selling...

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