"Rear Axle Differential Temp Increased, Decrease Speed" warning

[EXP Jawa]

1.7 L roughly.

Which means its about 2 pints less than the old live axle, IIRC. That's still not a huge volume. I am curious, really, with as little pooling as there really is, how well a remote cooler actually helps. What I mean is, the system and its flow doesn't really lend itself well to having the lube picked and pumped out to a heat exchanger. There's probably always going to be some air in the lines. Air in the lines insulates against heat transfer.

The late Z-28 used an axle cooler that was liquid-liquid. There was a heat exchanger that was placed inside the axle, in the inside face of the cover pan where the lube would flow over it. That was in turn plumbed to a cooling circuit outside the axle, and coolant flowed through the exchanger in the cover. So heat transferred from the lube to the cooler element in the cover, then from there out to a remote exchanger to dump the heat to the air. Actually, I think GM plumbed it into the transmission cooler circuit, and ran engine coolant through both. I think. If that's the case, then it would never bring the axle temp below 200 degrees or so, but that's still better than being at 300+. I've seen other axle systems that used a similar set up.

Perhaps a better aftermarket solution to the problem is for someone to develop a cover that swells out at the bottom, both adding volume and enclosing an internal heat exchanger core as described above. It would also include an air-liquid core (like a trans cooler) and a pump, and the system could be filled with antifreeze or water/Water Wetter. You'd mount the external core and pump like several people are doing above, but you have a better system of transferring heat out of the oil (especially since the water jacket can be bled), plus added volume within the axle to boot. The more oil you can add within the axle carrier the better for absorbing heat, even if it is just a couple pints. Just my $0.02 if I were doing it...

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[Matt P]

What Multimatic uses in their set ups must work pretty well, they won again!

"Multimatic Motorsports' Billy Johnson and Scott Maxwell won their third IMSA Continental Tire SportsCar Challenge race in a row Saturday at Road America in the No. 15 Ford Shelby Mustang GT350R-C"

 

[GTP]

This is a photo looking up at the 3.15 diff on my 2016 auto car. Is the black line with elbow the temp sensor?

 

[Plimmer]

^^ if that is the top of your diff its the breather / vent

 

[Optimum Performance]

Your car does not have a sensor.

 

[ANGST]

I wonder if Ford did anything in the 17's to improve on the diff cooling ?

Right now this thread is keeping me from getting a S550

 

[Brent Dalton]

As I was trying to figure out what model cars had the diff sensor, I walked around a large ford dealership with quote a few 17's. It appears there is no change for 17. FWIW, I think changing the fluid to a 75w110 or higher makes it good enough for track days in the summer.

 

[GT_Roadcourse_Newb]

Agreed. I think the problem with the diff temp on track can be avoided with some preparation.


Some lessons Ive learned- (I was a bit too aggro off the dealer lot so some are specific to noobs like me (e.g. #1))


1) I should have broken in the car a bit more, maybe 1000 miles with some very intermittent heavy work on the diff. (find a safe place to do a few tight circles with TC on)

2) Replace diff oil with 75/110 up to 75/140 before track duty.

3) Run HPDE events with TC ideally off or almost off.. take it easy and learn w/o assists, especially if you are looking to push the car to near what you can handle soon.

4) Exhaust wrap is a big help, especially with aftermarket pipes. Wrap pipes that would radiate heat most directly to differential to reduce the susceptibility of the diff temp to overheating from exhaust heat.

5) Take every 3rd or 4th lap as a semi-cooldown depending on how it's been going..! (can still go fast-ish, but w/o taxing the diff... I would like to hear from folks on how else to do this, but obviously going easy in turns would seem the obvious thing to do - still going for it on straights)..

my .02

 

[GTP]

My first race track day is in two weeks. I ordered some exhaust wrap, and I will replace the diff fluid with 75W-140 full synth gear lube. (Do I need to add 4oz Friction Modifier?)

Also, I looked into stick-on temperature strip gauges and found these (for non-PP cars):

P/N 4A-280 provides 280-290-300-310F dots (~$30 with shipping for a pack of 10). The center turns black upon reaching the labeled temperature.

 

[GTP]

Also available from Omega, and having the potential for a more exotic setup is this temp probe. I don't know if the diff casing is tapped for a NPT hole, but I suppose one could be put in it.

Either run the leads to a data input somewhere, or at least run the cable to the rear wheel opening, and then put on the K-type connector. Then you could simply plug in your K-type DVM to get a reading in the pits, lol.

 

[Optimum Performance]

I will replace the diff fluid with 75W-140 full synth gear lube. (Do I need to add 4oz Friction Modifier?)

Depends on the oil. Most Aftermarket Oils contain the additive and should say on the bottle.

 

[GTP]

Depends on the oil. Most Aftermarket Oils contain the additive and should say on the bottle.

Bought this from [MENTION=8761]Jmeo[/MENTION]:

 

[EXP Jawa]

If you bought the Motorcraft oil, then no modifier is blended in. You'll need to add it for the Traction-Lock diff. Clutches tend to chatter a bit without the modifier. Aftermarket fluid often have it blended in if they're labeled as "Limited Slip" oils, but Ford keeps it separate because the lube and the modifier have separate specs and part numbers. That also gives the dealers one more billable line item...

 

[Bahndvr]

If you bought the Motorcraft oil, then no modifier is blended in. You'll need to add it for the Traction-Lock diff. Clutches tend to chatter a bit without the modifier. Aftermarket fluid often have it blended in if they're labeled as "Limited Slip" oils, but Ford keeps it separate because the lube and the modifier have separate specs and part numbers. That also gives the dealers one more billable line item...

I thought the 15/16s did Not have clutches?

 

[MaverickGT]

I changed my fluid today and it had a bad smell to it and looked dark. It had 3 hours of run time on it and I saw the diff temp warning a couple times that weekend. It was 75w-90 full synthetic. It was a fresh fluid change a couple weeks before that event. I went with 75w-140 this time.

*Edit* - it had 6 hours track time but I only saw the warning light last event.

Question - are any of you changing your fluid that frequently after seeing the warning light? The owner's manual states to change every 12 hours of track time.

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