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2018 GT PP2 Rear Differential Overheating Issue

JohnD

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Kinjirra;2301431 Even the 350's don't have active coolers. [/QUOTE said:
They do now, after the first year of embarrassing GT350 overheating issues they put coolers on all GT350s.



I use 75W140 BG and have yet to have any significant heat in the rear end, BUT I don't track the car in the heat of summer.
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Kinjirra

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They do now, after the first year of embarrassing GT350 overheating issues they put coolers on all GT350s.



I use 75W140 BG and have yet to have any significant heat in the rear end, BUT I don't track the car in the heat of summer.
Far as I know they have passive coolers.. no fans since they are routed where there is proper airflow. Active cooling to me is fans and the works. I think fans are overkill since your not overheating sitting still.
 

TennTex

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There's an older thread on this topic pre-PP2, and seems like the same points.

My personal experience:
- Changed to BG 75W-140 from Optimum Performance (also their MT-82 oil...)
- Added wrap to the exhaust (I started from the muffler end, and didn't get as far past the diff as I meant to. Actually thinking of moving part of the wrap.)

Running at MSR - Cresson, TX, on the 3.1 mi. track I've only had the diff warning twice. Sunny weather, 75~85F ambient temp., definitely not peak-summer.

1 - Stock fluid and no wrap (Fall 2017). Got the warning when I ran a "red-check" ride after only ~30mins of cool down.

2 - After the 140W fluid and wrap (Spring 2018). Got the warning during a member day with a lot fewer cars on track. Rather than a 20 min session with maybe 15 mins at speed, I was running 20+ mins at speed in a 25 min session.

So, in both cases, being > 20 mins and/or with less cool down in-between was enough to get the warning. This stint time seems to be right at the tipping point for getting the warning, but would be shorter on a 95F day!

Other factors would be track temp, how hard the car is being pushed, and track layout (short or long straights).
 

Hack

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Did some research last night. Setting up even a passive cooler for these cars looks doable...very doable and without spending 800 bucks. I don't see why you would need anything beyond passive cooling unless your driving a full time racecar. Even the 350's don't have active coolers. Might be my next project, get some mesurements and find a few airflow areas that wont get in the way of anything.
Yes GT350s have a passive setup (meaning no fan on the radiator), but they also have under body air scoops to direct the air into the radiator. There also is an electric motor that circulates the fluid, so the GT350 setup isn't completely passive. I think it would be possible to do a passive (no fan) setup as long as you did something to point air at the cooler.
 

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Yeah, I don't know why Mishimoto isn't looking at a diff cooler. As they have already done some s550 cooling stuff.

Having 1 option and a couple of Band-Aids seems odd for a car that has been around almost 4 years, and has had the identified problem for 3.
 

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Kinjirra

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Yes GT350s have a passive setup (meaning no fan on the radiator), but they also have under body air scoops to direct the air into the radiator. There also is an electric motor that circulates the fluid, so the GT350 setup isn't completely passive. I think it would be possible to do a passive (no fan) setup as long as you did something to point air at the cooler.

Ya I've done the initial and its seems more then possible to set something up without dropping a ton of money. Couple hundred bucks since a pump is required and you don't want it dieing on you. Plus you want quality fittings and hose..shooting your diff fluid all over a track would be bad or on the drive home for that matter.

its an active project but not the top of my list atm. I will post something up if I come up with a kit on the cheap and easy
 

sigintel

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2018 PP1 diff testing

Should be 100+ ambient this weekend.
I plan on getting some baseline testing in at DWA soon.
I hope to come up with a solution for this and anyone can copy it for free.
If we need parts made, I can try sourcing them local or china if there was enough interest (part of my day job).

We need the problem defined properly, and some solution constraints.

Problem: diff roasting in oven created by exhaust.

Constraints:
Cost <<1000
If parts need to be shipped, try and keep them small.
Basic tool install - avoid welding
Try aiming for hardware store, tractor supply, or other common material source
Might need some silicon brake duct from pegasus racing or other cheap reliable source

Theory(just starter thoughts ):
Assuming track conditions
Exhaust gas temps are 500-1400F,
exhaust pipe prolly 600F+ in Track conditions
Air temps around diff prolly 250 to 400F
Diff needs to stay below 280F target at 105F ambient (for margin)

Test1:how bad is it?
Get baseline

Test2: can air routing fix it?
see if air cool alone buys us time we need
Order brake duct electric fan
Order high temp silicon hose
Order aluminum and maybe stainless foil to protect silicon hose
Order stainless sheet or stainless screen to sandwich fiberglass to make a high temp duct housing around diff to pump cool air into.

Test3: fluid heat transfer?
Can we use existing AC heater core or trans coolant lines to cool diff?
Still thinkn thus out.
Possibly braze lines onto back of diff to pump fluid thru?
 
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93tankus

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I like it!! I’m certainly interested in where your idea(s) take you!


Should be 100+ ambient this weekend.
I plan on getting some baseline testing in at DWA soon.
I hope to come up with a solution for this and anyone can copy it for free.
If we need parts made, I can try sourcing them local or china if there was enough interest (part of my day job).

We need the problem defined properly, and some solution constraints.

Problem: diff roasting in oven created by exhaust.

Constraints:
Cost <<1000
If parts need to be shipped, try and keep them small.
Basic tool install - avoid welding
Try aiming for hardware store, tractor supply, or other common material source
Might need some silicon brake duct from pegasus racing or other cheap reliable source

Theory(mine ):
 

PoppinJ

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Ill be hitting the track up in a week. 98 degrees is the current projected high. Ill be wrapping my exhaust and changing fluid to 75w-140 to see if it helps. I was getting the warnings about 15 min in or so last time. Honestly, your solution sounds really tricky. I think all thats needed is a fairly thin piece of custom molded sheet metal that acts as a heat shield between the exhaust and diff, and has a small scoop at the bottom to funnel air towards the diff, similar tot eh scoop for the manual tranny from ford racing, or the scoops on the PP control arms for the breaks.


If the heat shield was formed correctly there are plenty of bolts back there to use and it would be a no welding option.
 

sigintel

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Ill be hitting the track up in a week. 98 degrees is the current projected high. Ill be wrapping my exhaust and changing fluid to 75w-140 to see if it helps. I was getting the warnings about 15 min in or so last time. Honestly, your solution sounds really tricky. I think all thats needed is a fairly thin piece of custom molded sheet metal that acts as a heat shield between the exhaust and diff, and has a small scoop at the bottom to funnel air towards the diff, similar tot eh scoop for the manual tranny from ford racing, or the scoops on the PP control arms for the breaks.


If the heat shield was formed correctly there are plenty of bolts back there to use and it would be a no welding option.
Awesome! Test it!

No solution in my first post; just a list of raw materials to play around with to try getting the diff bathed in cool air.
Unlike the trans scoop, as you move rear of the trans, the air is now washing over the resonators picking up exhaust heat. At track loads, the exhaust and res are holding 1400F air and heating their external skin above 500F. Thats the problem I found w a scoop after resonator, it just grabs hot air and as I moved scoop lower, it got sheared off on track.
Basically, the diff is sitting in a funnel getting washed w air off headers,cats, resonator, trans, exhaust lines, and all the radiant heat off all the surfaces facing it. Keep in mind radiant heat transfer is 4th order of difference in temps; 700F exhaust pipe next to 250F diff is going to move serious wattage into diff before you even consider airflow.

Simple sheet metal scoop made of aluminum or stainless sheet seems staight forward. Im just afraid well be scooping hot air.

I tried a small scoop and sheared it on track on previous 2015.
I tracked my 2015 w Whipple. I roasted diffs, lol, bought 3x 3.15 aluminum from Coleman TX scrap yard for 800 on a pallet. Used 2 and changed oil after every 2 track weekends during cooler months (3rd one went on before trade in w new motor and stock trans). Had one bad bind up at TWC hitting turn 3 rise under full throttle and spun car: changed them more often after that and turned down Whipple.
Diff oil stinks!
Swapping diffs sux-especially if you fug up the half shaft clip uggghh.
 
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PoppinJ

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Awesome! Test it!
Swapping diffs sux-especially if you fug up the half shaft clip uggghh.
Oh noooooo. I dont have the skill to fab something like that... or the knowledge.... or the tools.... or the materials... I kinda suck. I was crawling around under the car today getting ready to wrap the exhuast and Im not even sure my idea would work. The diff is tucked pretty neatly underneath the exhaust. While driving the air is blowing over the engine, tranny, the full length of the exhaust and then kinda sorta onto the diff but not really because its tucked up so high.

Anywho, Im also worried about the wrapping the exhaust. It has small metal heat shields already between the pipe and the diff. If I wrap them Ill be insulating that area, not allowing air to flow between the pipe and the shield. I may be doing a good bit of work for nothing. If the wrap and the 75w-140 fluid doesnt really do much to help then I may pick up one of these tanny coolers. It looks like it forces a good bit of air across the tranny which is a bonus, but
would also funnel a good bit of air in the direction we want. Again, this would be hot air blown over exhaust and tranny, but still likely cooler air than a 300 degree diff. Id rather not have to mess with taking it on and off every time I hit the track though as it would be to close to the ground for daily driving. Not sure if this will fit a 2018 though.
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sigintel

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Oh noooooo. I dont have the skill to fab something like that... or the knowledge.... or the tools.... or the materials... I kinda suck. I was crawling around under the car today getting ready to wrap the exhuast and Im not even sure my idea would work. The diff is tucked pretty neatly underneath the exhaust. While driving the air is blowing over the engine, tranny, the full length of the exhaust and then kinda sorta onto the diff but not really because its tucked up so high.

Anywho, Im also worried about the wrapping the exhaust. It has small metal heat shields already between the pipe and the diff. If I wrap them Ill be insulating that area, not allowing air to flow between the pipe and the shield. I may be doing a good bit of work for nothing. If the wrap and the 75w-140 fluid doesnt really do much to help then I may pick up one of these tanny coolers. It looks like it forces a good bit of air across the tranny which is a bonus, but
would also funnel a good bit of air in the direction we want. Again, this would be hot air blown over exhaust and tranny, but still likely cooler air than a 300 degree diff. Id rather not have to mess with taking it on and off every time I hit the track though as it would be to close to the ground for daily driving. Not sure if this will fit a 2018 though.
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Nice pics!
Yup.
Under body air flow on scale of 1 to tits,
its a dirty diaper.
Lol, I got my hole saw out today and seriously considered cutting a duct to run cabin air thru 3” electric brake duct fan to a diff ‘bucket’. Totally pussd out.

Doesnt matter though, test session tomorrow cancelled due to TRACK CLOSED on account of heat. Gotta call and get scheduled some closed session durability testing. So embarrassing being at the track testing this. Still.., less embarrassing than spending 60k on GT 350 and getting powned by dude that spent his 20k in savings on 1LE on track days.
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CFAD1B07-3A33-4148-8FD5-A6A9F0E0F7FF.jpeg


The FP350S put the diff cooler in the front. American Muscle posted a video interview with a FP engineer explaining the oil cooling improvements.

Cheers,
 
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PoppinJ

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Ok, 75w140 and wraps installed, albeit sloppily. I shall see how it holds up next weekend in 100 degree temps. Also, does anyone know what this is? The thing im pointing to in the pic right behind the diff. Its like a flexible rubber... somthing. I thought the bolt was backing out at first.
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