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"Rear Axle Differential Temp Increased, Decrease Speed" warning

D K

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A finned cover would not help much. Nearly half of the diff sits in the cradle. Not to mention the movement the differential has in the cradle with the factory bushings.

My journey of tracking and the diff temp sensor on my 16GTPP. I received the light the first time on the car in nearly stock form(only a SW catback). This was mostly due to hot lapping the car. Car sat for only 5 mins and then it was back out on a short track.

After that I changed the fluid to amsoil (factory equivalent weight) and wrapped the exhaust. Never got the temp warning again until I did long tube headers.

My thought is that the cats on the factory system were holding a lot of the heat. Hence why I also found melted wire looms when removing the factory exhaust manifold/cat near the placement of the cat.

With the long tube headers, stiffer suspension(shocks, springs & sway bars) I was getting the temp sensor to hit after about 12-13 mins of a session at Hallett Mortor Raceway in June. Granted it was warm that day, with a high of 90°. I believe the long tubes with no cats and minimum restriction is allowing more thermal energy to travel down the system. Also the fact that the suspension got a bit stiffer could play into things as well.

Nonetheless I came the conclusion that it was necessary to add a cooler.
I ordered the Full Tilt Boogie Kit during their Black Friday special. Everyone I have seen use it has seen great results.

If I was contemplating a new PP1 or PP2 I would first change the fluid to amsoil 75w-140 and wrap the exhaust. Nothing permanent, overly substantial, or costly. Then go do a couple of track days and see if you get the prompt to come up.

Yea I wasnt talking about a finned cover but the ones that have provisions for the cooler.
I see them available with a cooling kit but havent seen them seperately
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Mountain376

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yeah i'm kind of surprised there isn't a finned one either but then again many of the aftermarket finned truck ones are rubbish. guessing though that the complexity of the standard cover would make the finned one an expensive casting. i downloaded a model of the ford 8.8 to play around in ANSYS with adding in fins but getting an accurate load case is difficult
A finned cover wont do much... Ford even originally looked at this while developing the S550... just look back at early photos.

The area in which the rear axle housing sits doesn’t allow much airflow; plus, the exhaust wraps around it...

TwinReverb covered this (good post to read).
 

GT_Roadcourse_Newb

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Can I ask a newb question? Why in any of this triage of the problem or design calculations, does the idea of trying to use more thermodynamically conductive materials, e.g. copper vs. iron/steel?

My wild idea would be a differential casing of copper, with insulated copper wiring running to a pair of copper winglets to provide additional passive cooling. Of course exhaust wrap would be essential in this setup.

Im not a materials scientist but I really like copper's properties. Thermal at least. Perhaps it expands too much to be used as something usually used by regular materials..?

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DB83

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Strength would be the main concern. The cover is still a structural part of the diff, and copper is a relatively soft maleable metal, so would likely deform quite easily and not provide the structural strength needed here.
 
 




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