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Discussion Starter · #1 ·
As an ice breaker....

Who has replaced or has considered replacing their stock transmission pan with one that is is finned? I'm talking 1/2" to 1" fins, something that will seriously excavate the heat. I know that there has been a number of coolers installed but that is overkill for my needs. I have thought of looking into a better pan for some time now. There seems to be a real potential at very little additional cost in helping out your transmission for the hotter months of the year. I would also think that a winter fin cover for we of the more northern latitudes would also be helpful if we went this route.

I had done some half hearted looking but thought that I might be reinventing the wheel so to speak and thought some of you may have already looked into this.

So let me know that your light years ahead of me and you've already found an aftermarket pan that has no fitment issues, cost next to nothing, has huge fins, and can back up boasts of working just as good as any air-water cooler...please. :)
 

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Well, I did a little more digging and still came up short. The process may not have been a total waste because I thought of a possible low cost solution. (Low cost compared to having one custom built) Buy a used stock NAG1 pan. Buy a used 4x4 aftermarket pan with big fins. Cut the same size hole out of the bottom of both and weld the fins into the NAG1 stock pan. Before I do this the cooling effects of the fins will need to be more thoroughly investigated. Because water and presumably transmission fluid is a better conductor and dissipater of heat than even aluminum open trough fins would seem to be the best. Again, I welcome any suggestions...
 

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It's a great topic, but in my car the whole pan is WAY too close to the road! I'm not doing anything to reduce my already low ground clearance.

I have found in previous rides (mostly trucks) that these types of pans simply caught a lot of debris.
 

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Discussion Starter · #4 ·
It's a great topic, but in my car the whole pan is WAY too close to the road! I'm not doing anything to reduce my already low ground clearance.

I have found in previous rides (mostly trucks) that these types of pans simply caught a lot of debris.
You bring up a great point, and one that has bothered me a little. My ride is an AWD so it rides a little higher stock than yours but I've lowered it substantially and probably lack even your clearance now. With all the mods that I've put on and under my car I've always maintained the bottom of the engine cradle as the lowest point. This standard may get challenged if I move forward with this fin idea, and that doesn't help this idea get any traction, so to speak. Hosing the pan off each trip to the car wash is ok with me but the issue with speed bumps and the like bother me. Thanks for the words of caution as I'll make sure I keep this dimension in mind as I move forward with this idea.

But getting back to the fin idea...it does seem that the truck crowd uses this method of cooling but strip and road course don't seem to, and that is puzzling to me. As you pointed out dirt will always be a maintenance issue and offroad seems to have a corner on that as well as constant clearance issue, but they are the one that seem to use this. In contrast a road course enthusiast would not have clearance issue, would maintain a much higher average speed, which would really help the cooling, and dirt wouldn't be as much an issue either, but they don't seem to use this. Go figure...

What has been the gnarliest, deepest fin pan that you have seen? And have you seen any open trough fin setups or seen on literature on them. I wonder if they are even made and if they are whether they work better than solid fin pans for cooling?
 

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The last one I actually bought came from Summit. It was for a 4L65E I had built up by my local trans shop to go behind a mildly massaged 6.2 liter GMC V8 in a Silverado.

It held an extra 2 quarts of fluid and had shallow finning all over the bottom. Nice piece, cast, pretty expensive.
 

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Do any of the AMG models use this tranny? If so, do their's have a different pan? Just an idea.
 

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Do any of the AMG models use this tranny? If so, do their's have a different pan? Just an idea.
SL 55/65 AMG. Not sure about a different pan, but I've been looking into using some Merc parts for a project. FWIW, their parts guys are absolutely useless. I've called multiple dealerships in various cities for parts, and it takes them days at best to get me part numbers so I can check compatibility and such. One guy did quote me $13,000 for a 7G Tronic, after he spent a week looking for the part number.
 

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Discussion Starter · #8 ·
The last one I actually bought came from Summit. It was for a 4L65E I had built up by my local trans shop to go behind a mildly massaged 6.2 liter GMC V8 in a Silverado.

It held an extra 2 quarts of fluid and had shallow finning all over the bottom. Nice piece, cast, pretty expensive.
The extra capacity sounds good but like you said considering the ground clearance issue, probably not sure a good idea for these cars. Getting a custom cast may turn out to be more affordable than I expect but I cringe each time I think about it.

Do any of the AMG models use this tranny? If so, do their's have a different pan? Just an idea.
I didn't even consider this as an option, thanks. It seems counterintuitive to look at Mercedes for an affordable part but if it doesn't require any modification it might just be the best priced option available.

SL 55/65 AMG. Not sure about a different pan, but I've been looking into using some Merc parts for a project. FWIW, their parts guys are absolutely useless. I've called multiple dealerships in various cities for parts, and it takes them days at best to get me part numbers so I can check compatibility and such. One guy did quote me $13,000 for a 7G Tronic, after he spent a week looking for the part number.
I hope to have better luck, but thanks for the warning.
 

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If your goal is to keep the fluid cool, I would consider adding a double stack tranny cooler, not a tube and fin cooler, instead of a larger trans pan which are not nearly as efficient , in series with the stock tranny cooler in the grille. I plan to add a Long Double stack 28,000 GVW cooler myself which I currently run on a 94 Mustang GT convertible outside of the radiator-the cooler does all the cooling.
 

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Agreed. New trans cooler is your best bet if you wish to increase the cooling capacity of your system.

But BEWARE!!! If the pressure drop across the cooler is different, the flow through the cooler will change and may actually cool the fluid less. The pressure drop across the cooler has an impact on how long the fluid remains inside the cooler to allow for the heat transfer to take place. You change this...and you may actually reduce the overall cooling of the system. To be sure, there is a fair amount of engineering design, testing and validation that goes into these systems based on the transmission pump spec's and cooler & fan location.

Also, the optimal trans fluid temp is around 170F. If the fluid runs too cold, parasitic loss in the transmission will cause unecessary drag and affect fuel economy, shifting, durability, etc. Have fun!
 

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Discussion Starter · #12 ·
I appear to be getting on in my years! I have not noticed that there was a response to this thread for over 3 months, and for that I apologize.

If your goal is to keep the fluid cool, I would consider adding a double stack tranny cooler, not a tube and fin cooler, instead of a larger trans pan which are not nearly as efficient , in series with the stock tranny cooler in the grille. I plan to add a Long Double stack 28,000 GVW cooler myself which I currently run on a 94 Mustang GT convertible outside of the radiator-the cooler does all the cooling.
I have no doubt that a double stack tranny cooler will work better than a simple finned tranny pan but for me it is excessive.
transcooler is your best bet
See above

Agreed. New trans cooler is your best bet if you wish to increase the cooling capacity of your system.

But BEWARE!!! If the pressure drop across the cooler is different, the flow through the cooler will change and may actually cool the fluid less. The pressure drop across the cooler has an impact on how long the fluid remains inside the cooler to allow for the heat transfer to take place. You change this...and you may actually reduce the overall cooling of the system. To be sure, there is a fair amount of engineering design, testing and validation that goes into these systems based on the transmission pump spec's and cooler & fan location.

Also, the optimal trans fluid temp is around 170F. If the fluid runs too cold, parasitic loss in the transmission will cause unecessary drag and affect fuel economy, shifting, durability, etc. Have fun!
You bring up a number of good points. Regarding the pump capacity or fluid exchange speed, because it is a closed system with both a variable heat source and dissipation rate the optimal pump rate would seem completely dependent on Tranny load/speed and ambient temperature, wouldn't it? Easy driving in Alaska would require a different exchange rate than hard driving in Florida for optimal heat exchange, yes? Regarding the optimal operating temp, driving habits and ambient temps would also seem to be necessary givens. In a high demand driving situation a 160 degree or lower base temp may be better as it allows a longer duration at excessive load and save the fluid from "burning". You sound like you have experience with this. How do you reconcile different driving habits?

Let me restate that for me a tranny cooler with a radiator is unnecessary in almost all applications. On occasion I stress my tranny fluid and I am looking for a reasonably priced solution that works in a very cool environment.
 

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I do not know what the standard design is on your car, but on mine the factory cooler is quite large and I actually have difficulty getting the fluid warm at all on the street! Even with tire shredding burnouts and such it just won't get hot.

We do share a thermostat, which will prevent overcooling if you buy a big aftermarket cooler.

Got any converter in there yet?
 

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Discussion Starter · #14 ·
I do not know what the standard design is on your car, but on mine the factory cooler is quite large and I actually have difficulty getting the fluid warm at all on the street! Even with tire shredding burnouts and such it just won't get hot.

We do share a thermostat, which will prevent overcooling if you buy a big aftermarket cooler.

Got any converter in there yet?
Just a 2800 stall. I drive out of the hole! You bring up a good point though, and one I've considered from time to time. Am I looking to solve a potential problem that will arise during 5% of my driving only to downgrade the performance during 50% of my driving. Additional cooling is not usually necessary at 10 degrees Fahrenheit.
 

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Agreed. New trans cooler is your best bet if you wish to increase the cooling capacity of your system.

But BEWARE!!! If the pressure drop across the cooler is different, the flow through the cooler will change and may actually cool the fluid less. The pressure drop across the cooler has an impact on how long the fluid remains inside the cooler to allow for the heat transfer to take place. You change this...and you may actually reduce the overall cooling of the system. To be sure, there is a fair amount of engineering design, testing and validation that goes into these systems based on the transmission pump spec's and cooler & fan location.

Also, the optimal trans fluid temp is around 170F. If the fluid runs too cold, parasitic loss in the transmission will cause unecessary drag and affect fuel economy, shifting, durability, etc. Have fun!
In theory you are basically correct, but my experience from years of using external tranny coolers is not what you describe. I have been using external tranny coolers for 30 years now on MANY types of cars and transmissions, and I have never had a tranny failure. My first application was in the late 70's with (2) tube and fin coolers on a Nova SS with a turbo350 automatic that was cooled exclusively outside of the radiator and I beat the crap out of that tranny and drove the car year round in weather down to 0 degrees in New England with zero issues. Sold the Nova with 168,000 on the tranny which never missed a beat.

Car manufacturers design their systems as a complex algorithm involving cost, longevity, warranty claims, packaging considerations etc-it is a one size fits all solution to the issue of containing heat buildup in a car's transmission-it is a compromise at best!

Modern Double Stack tranny coolers are designed to limit flow based on fluid temperature so that the coolers ability to achieve maximum cooling is dependent on the viscosity of the tranny fluid-it cools less in cold weather and more in hot weather. They are somewhat self regulating so to speak. The big limiting factor running external coolers outside of the radiator is the lack of a mechanical fan like in the 300 constantly pulling air over the cooler. I have not found this to be a problem in most applications with cars with A/C. In hot weather, the A/C causes the electric fan to run constantly and in cold weather it's a non issue. Currently, I have a 2001 Pontiac Grand Prix with (2) Long Double Stack 18,000 GVW coolers in the grille (electric fans like the 300) which I drive all year long including VERY cold winters-no issues-140,000 miles on the tranny now and the 4T65E FWD tranny is NOT known for longevity. I have not experienced any parasitic losses that I can feel either from the power stand point or gas mileage-no change with either. This trans runs about 115-120 in the winter and 135-140 in very hot weather. I change the trans fluid and filter every 25,000-30,000 miles and the fluid looks great and the pan is clean as a baby's behind!

Lastly, the number 1 enemy of transmissions is heat-no way around that issue. I am not sure where the 170 degree optimal temp comes from BUT I know a number of heavy duty cooling systems in cars with external tranny coolers where the number is closer to 115 degrees. I can assure you and I have verified this fact that trans fluid temps with factory trans cooling systems run MUCH higher than 170 after a high speed run @ 80+ MPH in overdrive in moderately warm weather, not hot weather-my Mustang GT would run easily over 200+ routinely. Try touching the Trans lines after such a run-they are REALLY HOT-check it with an IR thermometer. Remember this thermodynamic fact-if the cars radiator system runs 195-200 degrees, the tranny fluid running through that system for cooling can NEVER be less than 195-200 degrees-never. The Mustang runs about 145-150 degrees on very hot days with a 28,000 GVW Long Double Stack cooler doing all the cooling. No issues with the tranny.

One last Important point! 300's without an external Trans cooler from the factory-my Limited does NOT have one-use the lower 1/3 of the A/C condenser (not the top 1/3) to AIR COOL the trans fluid-out of the main airflow. This system is a giant compromise and pretty much useless in cooling transmission fluid in stop and go traffic with no A/C electric fan running. I plan on mounting my Long Cooler right below the power steering cooler, exposing about half the cooler to direct airflow and to remove the plastic covers in the lower bumper on either side for increased airflow at speed.

Some Facts about Long/Dana Coolers:

Long coolers are made by the Dana Corporation who make most of the OEM coolers found on cars with heavy duty trans duty-Police cars should come to mind.

Long Coolers have what they call "Tru-Cool LPD" (low pressure drop) technology that "allows colder thicker ATF to flow more efficiently through two open bypass channels positioned at the top of the cooler. As operating temperatures increase, the ATF becomes hotter and thinner. It's then directed through the core where it is cooled. Tru-Cool's Highly efficient cooling technology combines improved protection against lube system failure with optimal heat transfer". I use Long coolers only.

Part #'s:

LPD4589-GVW rating -24,000Lbs-My Mustang GT has this one
LPD4454-GVW rating-18,000 lbs-I have 2 of these on the GP
LPD4590-GVW rating-28,000 lbs-Putting this one on the Chrysler 300

Long has many other coolers beside what I am using above in various GVW ratings and sizes.

Other advantages of the Double Stack Long Coolers:

1. Deliver 15 times less flow restriction than Tube and Fin coolers
2. Self regulating for Maximum ATF flow
3. Long Built Coolers are original equipment on 9 out of 10 new Vehicle installations- I would bet that Dodge uses Long Coolers for Trans/Oil cooling on the Charger Police Cars
4. Life Time Warranty

Pretty self explanatory why I have been using Long Coolers for a LONG time-no pun intended.

Running a trans cooler of some sort is ALWAYS a good idea-cheap insurance.

Hope this helps!
 

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Just found this B&M RACING has: #10300 Deep pan & has a drain plug. That fits the NAG1. If I find any others I'LL post them here.:::.PML has 3 different pans for nag1:#11117-1 1/2-2 qts;#11124-2-2 1/2 qts.;#11132stock capacity.These are finned with no name.
 
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