MMR Differential Oil Cooler Kit Install- Update 9/21/24 Track Testing

[krisk]

I figured I'd write up a summary of my experience with the MMR (@Mod Mustang Racing ) differential oil cooler kit install. Overall the kit is a great deal at $699.99 compared to most of the other kits out there, and when you price out the components, you really wouldn't come out any cheaper sourcing individual parts yourself. This kit is listed as for the 2015-2024 Mustang. Here are some comments.

1. The kit just comes with the instruction sheets for each individual part (cooler/fan, pump, and thermostat relay). I did call MMR about instructions before I received the kit and they said it was pretty self explanatory and the individual parts did have instructions. I'm not by any means an ASE certified mechanic, but I've done my fair share of automotive work over the year. With some basic automotive knowledge, they are correct, it is not that difficult. However, for someone like me who overthinks everything and wants perfection, that adds up to several hours of extra “planning” time for the install.

2. Initially I ordered the kit with the pre-drilled differential cover because the kit without it warned that drilling may be required. After some research it looked like drilling may not be required, so I checked with MMR and they confirmed the kit could be installed without drilling. They were very accommodating in updating my order to remove the cover and give me a refund since my order had not yet shipped.

3. The kit did not come supplied with the wiring to connect everything. The only wiring was the thermostat relay. This wasn’t a big deal and I’m not certain if this was a mistake that wiring was not sent or if that is how they normally supply the kit. I didn’t worry about it since I had to buy a few other parts, and I never contacted MMR to ask although the picture on their website of the kit did show extra wiring.

4. Technically you could make the kit work just by adding some wiring with the components they provided. However, I wanted an on/off switch so it would only run when I wanted it to rather than being solely controlled by temperature, so I purchased a push button switch. Just to be safe, I also added a relay which the switch controlled so I wouldn’t have to worry with how much amperage was running through the switch. I also bought bus bars to connect the positive and ground cables by the cabin fuse panel, a 12 gauge fuse tap, and fuse block & bus bar for the trunk so I wouldn’t need inline fuses for the pump and fan. Lastly, I bought some Deutsch connectors for the temperature probe, pump and fan so everything could be easily disconnected under the care in the event component replacevent was necessary. Most of this could have been wired by splicing wires together, but I want it to be done as professionally as possible, so I went with this setup.

5. I’m not sure if all S650s have the covering that runs from the differential to the rear bumper which conceals the charcoal canister and area underneath the spare tire well, but it seems to me the cooler kit was not setup to accommodate the cover. Pictures on MMR’s website of the kit installed to not show the cover, which makes sense given you can’t see much if it was installed, but I could not figure out a way to get the 45 degree AN fittings to connect to the diff cover as long as the metal bracket for the underbody covering was installed. Maybe it’s possible, but I couldn’t figure out a way. Initially I decided I would just leave the cover and bracket off, but it ate at me long enough thinking about it that I decided to try to make it work. I bought a couple 90 degree AN fittings and that made it where I could route everything through the stock covering and bracket. It makes the hoses run really close to the exhaust, but I’m going to extend my exhaust wrap further back to prevent any issues with overheating the hoses.

6. Also, the block supplied into which the relay temperature probe is to be installed comes with 1/2” FNPT threads, and with the supplied hardware in the kit, the only place I could figure to install it was either the inlet or outlet port on the diff cover. It makes more sense to run it from the outlet (lower) port, but again, the metal bracket that holds the covering for the rear of the car does not allow enough room to install it directly to the outlet port. My workaround was buy a couple of 1/2 MNPT to -8 AN flare fittings to connect to the block as well as some straight AN hose fittings and install the block and temperature probe in the middle of the hose under the covering in between the outlet of the diff cover and the inlet of the cooler.

7. I do like the fact they supplied just a length of AN hose so the setup could be customized to run however I wanted. I ended up with about 3 feet of hose remaining when I got done.

I am happy with the kit, and I do think it was a good deal even with all of the extra stuff I ended up doing to make it work the way I wanted. It took me WAY longer than it should have to install because I wanted everything perfect, but I like the way it turned out. I initially thought about doing a YouTube video of the install, but the desire to do so left me very quickly once I got started, and all I was worried with is getting done. If anyone has questions about how I did certain things, feel free to ask and I’ll help in any way I can. I would 100% buy this kit again over the other available kits on the market based on the price and quality of components. I haven’t been to the track with the car since installing, but I’ll be sure to add my comments on how it does keeping the temperatures under control once I get it on the track.

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[steveo1960]

I figured I'd write up a summary of my experience with the MMR (@Mod Mustang Racing ) differential oil cooler kit install. Overall the kit is a great deal at $699.99 compared to most of the other kits out there, and when you price out the components, you really wouldn't come out any cheaper sourcing individual parts yourself. This kit is listed as for the 2015-2024 Mustang. Here are some comments.

1. The kit just comes with the instruction sheets for each individual part (cooler/fan, pump, and thermostat relay). I did call MMR about instructions before I received the kit and they said it was pretty self explanatory and the individual parts did have instructions. I'm not by any means an ASE certified mechanic, but I've done my fair share of automotive work over the year. With some basic automotive knowledge, they are correct, it is not that difficult. However, for someone like me who overthinks everything and wants perfection, that adds up to several hours of extra “planning” time for the install.

2. Initially I ordered the kit with the pre-drilled differential cover because the kit without it warned that drilling may be required. After some research it looked like drilling may not be required, so I checked with MMR and they confirmed the kit could be installed without drilling. They were very accommodating in updating my order to remove the cover and give me a refund since my order had not yet shipped.

3. The kit did not come supplied with the wiring to connect everything. The only wiring was the thermostat relay. This wasn’t a big deal and I’m not certain if this was a mistake that wiring was not sent or if that is how they normally supply the kit. I didn’t worry about it since I had to buy a few other parts, and I never contacted MMR to ask although the picture on their website of the kit did show extra wiring.

4. Technically you could make the kit work just by adding some wiring with the components they provided. However, I wanted an on/off switch so it would only run when I wanted it to rather than being solely controlled by temperature, so I purchased a push button switch. Just to be safe, I also added a relay which the switch controlled so I wouldn’t have to worry with how much amperage was running through the switch. I also bought bus bars to connect the positive and ground cables by the cabin fuse panel, a 12 gauge fuse tap, and fuse block & bus bar for the trunk so I wouldn’t need inline fuses for the pump and fan. Lastly, I bought some Deutsch connectors for the temperature probe, pump and fan so everything could be easily disconnected under the care in the event component replacevent was necessary. Most of this could have been wired by splicing wires together, but I want it to be done as professionally as possible, so I went with this setup.

5. I’m not sure if all S650s have the covering that runs from the differential to the rear bumper which conceals the charcoal canister and area underneath the spare tire well, but it seems to me the cooler kit was not setup to accommodate the cover. Pictures on MMR’s website of the kit installed to not show the cover, which makes sense given you can’t see much if it was installed, but I could not figure out a way to get the 45 degree AN fittings to connect to the diff cover as long as the metal bracket for the underbody covering was installed. Maybe it’s possible, but I couldn’t figure out a way. Initially I decided I would just leave the cover and bracket off, but it ate at me long enough thinking about it that I decided to try to make it work. I bought a couple 90 degree AN fittings and that made it where I could route everything through the stock covering and bracket. It makes the hoses run really close to the exhaust, but I’m going to extend my exhaust wrap further back to prevent any issues with overheating the hoses.

6. Also, the block supplied into which the relay temperature probe is to be installed comes with 1/2” FNPT threads, and with the supplied hardware in the kit, the only place I could figure to install it was either the inlet or outlet port on the diff cover. It makes more sense to run it from the outlet (lower) port, but again, the metal bracket that holds the covering for the rear of the car does not allow enough room to install it directly to the outlet port. My workaround was buy a couple of 1/2 MNPT to -8 AN flare fittings to connect to the block as well as some straight AN hose fittings and install the block and temperature probe in the middle of the hose under the covering in between the outlet of the diff cover and the inlet of the cooler.

7. I do like the fact they supplied just a length of AN hose so the setup could be customized to run however I wanted. I ended up with about 3 feet of hose remaining when I got done.

I am happy with the kit, and I do think it was a good deal even with all of the extra stuff I ended up doing to make it work the way I wanted. It took me WAY longer than it should have to install because I wanted everything perfect, but I like the way it turned out. I initially thought about doing a YouTube video of the install, but the desire to do so left me very quickly once I got started, and all I was worried with is getting done. If anyone has questions about how I did certain things, feel free to ask and I’ll help in any way I can. I would 100% buy this kit again over the other available kits on the market based on the price and quality of components. I haven’t been to the track with the car since installing, but I’ll be sure to add my comments on how it does keeping the temperatures under control once I get it on the track.

Nice write up... How did you take such clear pictures, especially the close ups?

 

[krisk]

Nice write up... How did you take such clear pictures, especially the close ups?

Thanks. For the photos I just zoomed out as much as possible with my iPhone.

 

[n_123]

Just so I understand, the kit comes with an automatic temp sensor that will turn the pump on when it gets to a specific temperature and you installed the switch in the cabin as a backup? I kind of dig the idea of just having the sensor and nothing in the cabin besides the fact that you don’t know if the damn thing is actually working given that non performance pack cars don’t have a temp sensor back there (thanks Ford). Is there any way to determine if it stops working from within the cabin or do you have to get under the car to see?

 

[krisk]

Just so I understand, the kit comes with an automatic temp sensor that will turn the pump on when it gets to a specific temperature and you installed the switch in the cabin as a backup? I kind of dig the idea of just having the sensor and nothing in the cabin besides the fact that you don’t know if the damn thing is actually working given that non performance pack cars don’t have a temp sensor back there (thanks Ford). Is there any way to determine if it stops working from within the cabin or do you have to get under the car to see?

The kit comes with a temperature sensing relay, which does have two leads, so theoretically you could wire it to switch both the fan and the pump on using the relay. The problem is if the probe is installed in the MMR supplied block, then at best it is reading the temperature of the fluid inside of the fittings a couple of inches outside of the differential. To actually have it be triggered by the fluid temperature inside the differential, then you would have to drill and tap the cover and install it there. Unless the pump is running or you install the probe in the diff cover, the temperature probe is only reading the fluid temps in the cooling lines since the fluid does not circulate without the pump.

The switch I installed supplies power to the pump regardless of temp, and the relay triggers the cooler fan to turn on only when the temperature of the probe exceeds the set value. This works since the pump will circulate the fluid from the axle to trigger the relay. Without the fluid being circulated, the relay likely wouldn't come on until the oil in the axle was way too hot.

If I had a car without the factory temperature sensor installed, I would add a sensor which displays the axle temp rather than just using an on/off relay. I'd be concerned not knowing how hot it was getting.

You'll know if it stops working because the pump is loud. You can't hear the cooling fan inside the cabin, but you can if you are standing at the back of the car. Now, if you're on the track, you likely wouldn't be able to hear the pump, but if you're just cruising around town you will absolutely know if it is on or not.

 

[timd38]

Great write up! My Dark Horse has a NACA duct to send air to the cooler, wonder if anyone will offer a rear defuser with a duct to feed cold air to the cooler.

 

[krisk]

Great write up! My Dark Horse has a NACA duct to send air to the cooler, wonder if anyone will offer a rear defuser with a duct to feed cold air to the cooler.

That would certainly be an option. Steeda sells the differential cooler using the factory setup with the cooler located in the rear diffuser with no fan. The issue is with the S650 that did not come with the factory cooler there would be very little airflow over the fins, so the main benefit would be having a larger capacity system. I haven’t seen the underside of the Dark Horse, so I wasn’t sure how they set up the airflow to flow over the cooler. It would be nice to be able to install the factory system, but it would likely require a new diffuser as well. Plus the factory Steeda system was almost twice the price of the MMR system.

 

[Wiley Marmot]

Well! If II ever decide I want, or need an oil cooler; I'll darn well refer to this excellent write up!

 

[LoneRanger57]

The routing of the cooler lines is exceptionally close to the exhaust pipes, I would try to get some clearance and add crab leg insulation on the lines

 

[nashbridges]

Nice install. Looks very clean. Just curious, what temp was your diff running under hard driving and what temp rang are you shooting for now with the cooler? I've never really paid attention to diff temps as I've never had the temp reading and didn't think it mattered much.

 

[krisk]

The routing of the cooler lines is exceptionally close to the exhaust pipes, I would try to get some clearance and add crab leg insulation on the lines

Although the hoses are router closer than I would like, only seeing it in two dimensions in the picture makes it looks closer than it actually is. I am going to rerun the exhaust wrap to take it further back and completely cover the area near the hoses. Unfortunately, if keeping the underbody cover, there aren’t any safe routing options that keep it further away from the exhaust. You can’t see it in the above picture, but you don’t have any clear run for the hoses above that aluminum bracket because it is custom cut to fit in between the exhaust hangers, and there is not sufficient room between the two to run the hoses except in the places where I’ve routed them. That is why I went back and forth about removing the underbody cover, but ultimately decided it should be fine as long as the exhaust is wrapped.

I do like your recommendation about adding some insulation to the oil cooler lines. If I’d thought about it when I was ordering the extra parts I surely would have done it, but for some reason I didn’t think about it.

 

[krisk]

Nice install. Looks very clean. Just curious, what temp was your diff running under hard driving and what temp rang are you shooting for now with the cooler? I've never really paid attention to diff temps as I've never had the temp reading and didn't think it mattered much.

Running around town or on the highway the axle temps get up to around 200 degrees and then hang out in that range. On the track they were hitting 300 when the temperature warning would appear. I’m hoping with the cooler I’ll be able to keep them under 200. The thermostat on the fan is adjustable and is set at around 185 right now. I may play with the setting once I see how it affects the temperature. I don’t plan to use the cooler except when running on the track as it really isn’t needed from what I have experienced.

 

[krisk]

The routing of the cooler lines is exceptionally close to the exhaust pipes, I would try to get some clearance and add crab leg insulation on the lines

Before my first trip to Atlanta Motorsports Park I extended the exhaust wrap further back and also put heat wrap around the cooler lines.

Here’s the results of my track day at AMP yesterday. It was pretty warm, upper 80’s, so I worked out well for testing the cooler. I ran a total of five sessions throughout the day and never had a bit of trouble with the axle overheating. My last session was from 4:30 to 5:00, and it was hot out. I started the session with the axle around 180 degrees, and after 30 minutes on the track with the cooler pump and fan running the whole time it was 240 coming off the track. Given most of my sessions will usually be 30 minutes or less, the cooler should enable me to run all day long without a problem. I’m happy to not have to worry about the overheating axle anymore.

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