Trans Cooler Wisdom

I am helping a friend build a 1966 F100 and I have been placed in charge of making all technical decisions. the truck has a 390 with a C6 and it is being designed to be a weekend driver and an occasional commuting vehicle. I expect the truck to spend a significant amount of time in stop and go traffic, so I want to overbuild the cooling system. I am weighing the options of going with a Derale frame mounted transmission cooler or a traditional cooler mounted in front of the A/C condenser. Should I route the fluid through the cooler in the radiator before going to the aux. cooler to warm it up on short trips or should I bypass it altogether to keep the heat out of the transmission. Also I am a little iffy about the lack of airflow using a frame mounted cooler. I'm probably over thinking this since the truck will never be used for towing or hauling, but I'd like a few educated opinions before I table the next step and start ordering parts.

Through the aftermarket cooler first to cool the fluid and take the load of the engine's cooling system.

Then through the built-in cooler in the radiator to keep the fluid at operating temperature and, if it's towing and still hot after the aux cooler, the built-in will drop the temp some more.

We used a frame-mount cooler in a customer's fibreglass '34 Ford with a 700R4 trans but itt's only cooling a lightly loaded transmission. I would stick with a conventional style cooler to handle any serious cooling job.

Those frame-mount heatsink looking coolers only have the fluid make one pass through them, the old-fashioned ones have the fluid making multiple passes and have much more surface area.

You could also install a sending unit and use one of the fan-cooled trans coolers available now.

Hope this helps.

Shawn

On something like a budget tow rig you might only run a huge auxiliary cooler out front, anything that gets driven gently you will want the fluid warmed by the stock radiator cooler to help drive any moisture out of it.

I generally run the ATF through the radiator mount cooler first, then through the aux cooler. Since, as you say, there is a problem getting enough air to a frame mount cooler I like sticking them out front in the air flow. That way at idle the cooling fan pulls air across the cooler to help dissipate the heat of stop and go driving.

Those finned pans help but again they are in a weird airflow area and the smaller percentage of air going over them will have been heated by the engine, radiator, etc.

Another way to help cut down on trans heat is a 'shift kit'. The stock shifting is designed for comfort because people don't want to feel the transmission shift. This means that during a shift there are usually two clutch packs or bands slipping at the same time, one applying one releasing, and that generates heat each time it happens. To make the shift 'soft' the 'overlap' time is extended, just like a manual transmission slipping friction materials generate heat. A shift kit will cut down on that 'overlap' time, thus cutting down on heat.

Thanks for the input. I had not considered the airflow provided by the cooling fans at idle, but I was already concerned about the proximity of the headers that we just installed. I had seriously underestimated how much space would be occupied by them. I will try to get some pics of the project posted eventually. It has been fun truck to work on and it is a nice change to have a real budget to work with and someone else's money to spend!

In all the fords I have had I put a trans cooler out in front of the rad / condenser so it gets the first shot of cool air. My local trans shop does this mod to all the transmissions they rebuild and warranty. They swear by it. They actually delete the cooler in the radiator all together and only run a front mount cooler.

If your friend don't plan on towing anything i don't even see the need for anything other then the radiator cooler. I use my E250 van only for towing and have never had any issues with the C6 trans. It only has the radiator cooler.

I have only one thing to add. If you (or anyone else) decides to use a frame mount trans cooler, its imperative that it is mounted firmly to the frame because what it does is use the frame as a heat sink . If the flat mounting surface of the cooler isn't cleanly and firmly fixed to a substantial piece of frame metal it will be useless.

I've never used a frame mount trans cooler, but I do deal with a lot of heat sinks on electric forklifts and similar industrial vehicles. I've seen more than a few motor controllers and rectifiers burn out prematurely due to improper mounting. I use heat sink compound paste between the device and the frame generously, I would also use it if installing one of those frame mount trans coolers. Just my $. 02. YMMV.

mguar wrote: In reply to windsor deluxe: I have 400,000 miles on my pickup with the original untouched (except for fluid changes) transmission.. It has the stock in the radiator transmission cooler which quickly warms up the trans fluid and holds temps down during heavy hauling.. (remember it's stock) I've towed heavy enclosed tandem trailers over the Rockies and Sierra Nevada's dozens of times.. I've hauled home tons of wood and stone etc. to build my house, I'm sure regularly overloading it.. High speed (well over posted) and daily rush hour traffic it has never caused me to be concerned.. So don't over think it.. Don't spend money not required.. Change the fluid when it calls for it and it should be just fine..

What year make and model truck?

Some fords have and issue with intake manifold gaskets going bad. This lets the water level in the cooling system drop enough to expose the trans cooler in the rad and spells death to transmissions very quickly. However the motor will remain cool enough to run properly for a long time.

Ford explorers with the 4.0L motor were particularly a problem. These trucks got a reputation for bad transmission but in reality it was the motors that were killing them.

As above if you use frame mounted unit add this goop to the back. http://www.omega.com/pptst/OB-100_OB-200_OT-200.html

Their is a gray fibrous single stage stuff we use here at work but not sure where we get it. Bingo Good old McMaster 3568K1 Heat-Transfer Putty 1 Gallon Container, 750 Deg F Max In stock at $40.00 Each

Personally I did a auto trans swap in to a 38ft bus that i towed my 67 Dart drag car inside and the rad did not have a cooler so i went with 100% external cooler. with real hydraulic lines http://www.jegs.com/i/B%26amp%3BM/130/70266/10002/-1 never a problem but that trans was huge Allison unit

After forwarding your input to the truck's owner, he has decided to go with a conventional front mount cooler, however he has decided to use a frame mounted cooler for the power steering. This is a crucial addition to a vehicle that will never to any towing, heavy hauling or all that much steering in general.