2018 GT PP2 Rear Differential Overheating Issue

[Performance nut]

Out of curiosity, would it matter which brand 75w-140 we use? Mechanic I use is recommending Amsoil. Used Amsoil in the past for other stuff but never diff. Specs say you can use it 50-100k but is that under racing conditions?

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[gtorpedo]

Out of curiosity, would it matter which brand 75w-140 we use? Mechanic I use is recommending Amsoil. Used Amsoil in the past for other stuff but never diff. Specs say you can use it 50-100k but is that under racing conditions?

Amsoil is good. OPMustang sells BG fluid which is very popular. I recently started using Millers CRX 75w140 NT which is a bit more expensive, but its a competition grade race oil so should provide some extra heat/wear protection.

Ask Tim from OPMustang on fluid change intervals but I'd think after every 10 hours or so of track time.

 

[Mountain376]

I wasn’t driving much differently from the first time. If anything, I was probably a bit more tentative the previous time.

The only other thing that was different this time around was that I had it in “Track” mode (vs “Sport” mode the previous time). Not sure if that would have any bearing on diff temps.

I have to think the cooler ambient temps helped considerably. The 75w-140 oil may have made a small difference? But probably nothing notable, if at all.

Track vs Sport: There might be something there, as in Sport the TC/SC will intevene more, which can added heat transfered through the rear brakes. A lot? No, but “something “

The thicker fluid should be helping a decent anount - What is heat? What is causing it? Friction. Whether it be fluid motion or gear surface contact. If you control the hydrodynamic/boundary film better, you will lessen the heat. This is viscosity and composition (brand and type/formula). There are limitations though, of course. At some point, the friction reduction capabilty is reached, the system’s temperature becomes homogeneous and the environmental meets its heat transfer capabilities. Thats when a cooling medium comes in (i.e. airflow in some way)

 

[Hack]

I can't imagine that changing the fluid will impact the heat very much. I would just do a cooler. It's really not that terrible and IMO worth it for peace of mind.

 

[Mountain376]

I can't imagine that changing the fluid will impact the heat very much. I would just do a cooler. It's really not that terrible and IMO worth it for peace of mind.

If someone is mechanically competant, yeah. Or if they pay a professional to install it for them, yeah. Otherwise, it’s not really “peace of mind” as you add a possible failure point to the car if not installed correctly or place the heat exchanger somewhere vulnerable to elements...

I get what you’re saying, but I get tired of people talking about certain mods, saying it’s NBD because they can do it or they haven’t but the concept is simple.

I’m not trying to down-play anyones abilities or “troll”. Im simply saying this as a caution...

 

[Norm Peterson]

I can't imagine that changing the fluid will impact the heat very much.

I'd be afraid to even make a guess here. And I used to do some thermal transient analysis back when I had a "day job" (steam and water mostly, but still . . .).


Norm

 

[aleccolin]

The exhaust radiates an insane amount of heat, think it's literally the hottest thing outside of the engine. I didn't realize how much until I changed my exhaust and started getting crazy heat through the transmission tunnel doing hot laps. The exhaust runs even closer to that nice cast iron diff housing (why do we use cast iron for cooking?) what's needed is some proper heat shielding (not header wrap) to block that radiant heat. It's like if Ford was designing the exhaust to warm up the diff quickly, they did a great job, but unless you're in sub zero temps all the time it's a problem! Motorcycle style standoff heat shields would go miles toward improving the situation, and are not expensive. That plus a fluid change would be the easiest/cheapest/quickest first steps to take.

Couple different clamp-on heat shields can be found here: https://www.thermotec.com/products/heat-shields-and-protection

 

[aleccolin]

I can't recall, is the diff temp available in the center cluster menus, or do you need a scan tool of some kind to read it in real time? Could I read it with my BDX? Would be much easier for testing purposes.

Also, just found this comment from Torsen regarding the heat generated by the differential, which my gut tells me is MUCH less than that absorbed into the housing from the exhaust.

https://torsen.com/667-2/

 

[93tankus]

I can't recall, is the diff temp available in the center cluster menus, or do you need a scan tool of some kind to read it in real time? Could I read it with my BDX? Would be much easier for testing purposes.

Also, just found this comment from Torsen regarding the heat generated by the differential, which my gut tells me is MUCH less than that absorbed into the housing from the exhaust.

https://torsen.com/667-2/

On the 2018 PP2, the diff temp is one of the center cluster menu items. I keep it displayed when I'm on the track.

This is an interesting video(s) to watch regarding rear diffs and associated cooling. Lots of good information!
https://jalopnik.com/watching-gear-oil-splash-through-this-clear-differentia-1829278489

I like the stand-off exhaust wraps noted above! Certainly seems like an easy first step to try as well.

Cool discussion on this thread! Keep the ideas coming...

 

[aleccolin]

I ordered some heat shields for testing, just need to figure out how to access the factory temp sensor. I could rig some thermocouples on the outside but that's not oil temp or what the ECU is seeing.

 

[Performance nut]

If someone is mechanically competant, yeah. Or if they pay a professional to install it for them, yeah. Otherwise, it’s not really “peace of mind” as you add a possible failure point to the car if not installed correctly or place the heat exchanger somewhere vulnerable to elements...

I get what you’re saying, but I get tired of people talking about certain mods, saying it’s NBD because they can do it or they haven’t but the concept is simple.

I’m not trying to down-play anyones abilities or “troll”. Im simply saying this as a caution...

This. KISS applies to all things including modifying cars. Sometimes simple is better. A fluid swap and heat wrap may get you 80% of the way there and is pretty simple for just about anyone and quite affordable. A cooler... yeah, take a look at the GT350 diff cooler instructions. Dear lord, I want none of that noise.

 

[akitteh]

Newguy here with a newb question: this thread is great with lots of options to consider, but one thing is bothering me: is there actually a street legal (and California legal) diff cooler available for the 2018-19 GT?

The FP 350 cooler https://performanceparts.ford.com/part/M-4000-M8S states it's competition only, and says "Installation of this part on a vehicle driven on public roads and highways is likely to violate U.S. and Canadian laws and regulations relating to motor vehicle emissions." Why would a diff cooler have any bearing on emissions? Doesn't the street legal 350R have an equivalent setup? And if Ford Performance can't (or can't be bothered to) make theirs legal, why would the FTBR solution be any more so?

I'm just paper racing here, waiting for my PP2 on order, so bear with me :-) - It's unlikely I'll ever hit this problem, with my skills and the occasional track day, but I gotta pass the time somehow, so I like to scope out the options...

 

[NightmareMoon]

Newguy here with a newb question: this thread is great with lots of options to consider, but one thing is bothering me: is there actually a street legal (and California legal) diff cooler available for the 2018-19 GT?

The FP 350 cooler https://performanceparts.ford.com/part/M-4000-M8S states it's competition only, and says "Installation of this part on a vehicle driven on public roads and highways is likely to violate U.S. and Canadian laws and regulations relating to motor vehicle emissions." Why would a diff cooler have any bearing on emissions? Doesn't the street legal 350R have an equivalent setup? And if Ford Performance can't (or can't be bothered to) make theirs legal, why would the FTBR solution be any more so?

I'm just paper racing here, waiting for my PP2 on order, so bear with me :-) - It's unlikely I'll ever hit this problem, with my skills and the occasional track day, but I gotta pass the time somehow, so I like to scope out the options...

Just standard boilerplate for a Ford Performance product designed for the track. The actual part in question doesn't have anything to do with emissions, so the "likely to violate" phrase isn't the case here.

 

[akitteh]

Just standard boilerplate for a Ford Performance product designed for the track. The actual part in question doesn't have anything to do with emissions, so the "likely to violate" phrase isn't the case here.

Thanks. This is what I hoped would be the case.

 

[Hack]

If someone is mechanically competant, yeah. Or if they pay a professional to install it for them, yeah. Otherwise, it’s not really “peace of mind” as you add a possible failure point to the car if not installed correctly or place the heat exchanger somewhere vulnerable to elements...

I get what you’re saying, but I get tired of people talking about certain mods, saying it’s NBD because they can do it or they haven’t but the concept is simple.

I’m not trying to down-play anyones abilities or “troll”. Im simply saying this as a caution...

Your points are good. I added a rear diff cooler to my GT350 and it was a lot of work. Probably some people would not want to take it on as a project.

FYI - rear diff cooler is way easier than the transmission cooler, though.

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