Transmission cooler
 

I finally got the engine/transmission in my 67 Firebird project car and have run new 3/8" SS tubing for the cooling lines. Do I need to run through the cooler in the radiator and the auxiliary cooler or can I run through the plate cooler only? If I need to run through the radiator cooler as well does any one no of a fitting that will allow me to go from 3/8" tube to the 5/16" flair in the radiator? I would like to stay with hard lines only if possible.


Joe.

The question that begs to be asked, "Do you drive your car in the winter?" If you do, running the trans fluid into the radiator trans cooler will help warm the oil on cold days. If you only drive in normal temperatures I would avoid using the radiator trans cooler.

That's what I was hoping to hear. I don't have plans to drive it in the winter and it will be so much easier to plumb the lines to the auxiliary cooler only.

Thank you.

If it were me I would run it through the auxillary cooler first then thru the radiator and back to the trans. This way the trans oil gets up to operating temperature sooner and the radiator will keep the trans oil from getting too hot or too cold. It will keep trans oil temperature more constant and will add cooling capacity by using both coolers.

Tim, that was my original thought to but I don't know of a fitting that will let me adapt from a 3/8" hard line to a 5/16' female flair.
Where can I find a 1/4" Female NPT to 5/16" Male Flare fitting?

Note the comments here about routing and comments related to retaing the original in-radiator trans cooler in addition to using an auxiliary cooler:


http://www.hotrod.com/techarticles/g...s/viewall.html




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actually yo want to run it through the regular radiator first then through the aux cooler.

by passing the regular cooler has the added advantage that an overheating engine does not affect the tranny cooling

Tim is correct.Trans fluid can be "too cool".By hitting the Aux cooler first,this is eliminated.

Sorry,Steve by that HR article is wrong.

^^ I disagree, what happens when you are sitting in traffic and your engine is starting to overheat. If you plumb into the radiator first and then the external cooler now your trans fluid temps are closer to where they belong. If it goes through the radiator last you've simply re-heated the fluid to your coolant temp.

Modern external coolers self regulate based on the how thick the fluid is, colder fluid being thicker, less fluid goes through thus limiting the "over cooling" of the liquid.

You have it backwards,with the aux cooler first in line, and the temp of the fluid is too cold,then running it thru the radiator cooler brings it back into range.If the fluid temp is still too warm,then the radiator cooler has an easier time of temperature reduction.

"Coolant temp" is EXACTLY where you want the trans fluid temp.

The car will only see warm weather so I think I will plumb it through the auxiliary cooler then the Radiator cooler. I have a large plate cooler I am going to use and plumbing through the radiator cooler last should help stabilize the trans fluid temperature. If the car is running hot I think the engine would be in trouble before the transmission any way.

of course you can do what you want. But several sources, proffessionaly and highly qualified state that that you want to run it through the regular radiator first.

but what do they know.

they're only engineers and its their product.

The factory engineers say different.

Don't even waste money on an external cooler then because it won't do anything.

Edit: except add additional fluid capacity to the system.

http://www.carcraft.com/howto/transm.../photo_03.html

which factory?

the guys who make the coolers have specific instructions that confirm what many have recomended,

Ron Sessions , having written several articles and a few books on GM automatic transmission also confirms the same.

heavy trucks from the military with gm engines and auto trans ...ditto

so, which factory?


dont even get me started on what constitutes "too cold"

I run mine through a B&M stack plate cooler mounted in front of the radiator, not using the radiator cooler. I've got an autometer tranny temp gauge mounted on the trans output line going to the cooler. Once the car warms up, it registers 130-150F, engine temps 160-180 in 70F weather.

What temp T-stat does the book call for in your car?

Fluid Coolers
Most hot rodders know that a tranny cooler is something they should install, but many just haven't made the time to do so. Unfortunately, such a casual attitude may not be the right approach. "In any place other than Antarctica, you should install a transmission fluid cooler," opines Stan. "Anytime you separate the cooling of the transmission fluid from the radiator, where the temperature can run over 210 degrees, you will promote longer transmission life. Instead of the transmission fluid only being cooled to the temperature of the radiator coolant, it will now run about 20-30 degrees cooler than the engine by using a separate transmission cooler."

TCI Automotive

Comment from another source:

Line routing
"Auxiliary transmission coolers are more effective when routed in the return line of the transmission cooler rather than the feed line."

Another source:

"The most often asked question is should I bypass the radiator cooler when I install a auxillary cooler.
Most cooler manufactures and automobile manufactures information we have read, recommends installing the coolers In-Series with the factory radiator cooler for maxium cooling efficiency. So unless the manufactures who have spent 1000's of hours testing different installations are wrong, the suggested cooler installation is in-series. If you must bypass the radiator because the cooler tube is leaking or for other reasons, be sure to increase the size cooler you install by 1 to 2 sizes."

Another source:

"There is two lines of thinking on how the cooler should be installed. One is so the fluid goes from the transmission to the auxiliary cooler, then through the stock cooler built into the radiator and then back to the transmission. The second method is to have it flow through the stock cooler, then the aux cooler and back. That is the way mine is currently installed at the suggestion of the pros at Level 10."


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I would go thru the radiator first, then the auxiliary. Fluid cools, (or warms), to engine temp, then drops another ~20 degrees or so in the aux, before returning to trans. This should put the trans fluid temp around 160-175 depending on thermostat used.

From B&M:

B&M Super Cooler Mounting Guidelines
When considering installing a supplemental transmission fluid cooler B&M recommends the following guidelines for a successful and efficient installation:
● Route the transmission fluid through the stock radiator cooler, then through the supplemental B&M SuperCooler and then back to the transmission. This will provide the most efficient transmission fluid cooling system for your vehicle.

Agree
 

My 455 powered TH400 Buick has a Derale tubed pan on it with an external cooler not run though the radiator. My trans temp gage never goes over 140-150 degrees. I can't see a reason to heat the trans fluid to engine temp. A good look at that posted chart will tell you why. ;)

Then why did the factory engineers want the fluid returning to the trans at engine temp?

because at engine operating temperture, its still lower than the spike temps some tranny's experience under extream use. and operating tranny's at that higher temp for even a short period of time will cause internal damage and shorter life down the road.

and the factory does not want tranny fluid returning to the tranny at engine temperture per se. they want it to be cooled down to engine operating temperture when it is operated in a fashion that will raise its temp above opertaing temps to a point where it may cause internal damage. All party's concerned agree that if the tranny could operate at a cooler temp than engine temp it would be better still. Even the largest external cooler operating in winter time does not cool the temp much below 160 degrees which is an ideal temp for hd/towing use.

(not drag racing though!) Drag racing bearly raises the temp enough to be of concern so most racers remove the cooler and lines all together and just run the fluid right back into the tranny.

the radiator cooler is a comprimise in effectiveness and cost for a majority of users. those others that stress thier tranny's are either lucky, living on short time or have an external cooler. the radiator cooler is not effective in these small % of users.

You asked what temp is my T stat...180. I currently have a smog 400 and a manual tranny in my car and a 4 core ac cooling system so its not relevent. running without a t stat it ran so cool it did not even register on the guage

But I have 2 1957 GMC trucks with hydromatics and niether of them have any type of tranny cooler. but for 1 ton and above a cooler is standard and it runs through the radiator. as for mine. I cant even hook up a cooler if I wanted other than some sort of finned pan.

I have also owned corvairs/pg's with no cooler at all either. even some of the cheapest PG cars came from GM with out coolers of any kind.

I would rather not use the radiators transmission cooler if I can get away with it. Would it not be beneficial to the transmission to stabilize the fluid temperature at about 170 deg?

Just thought I'd throw my .02 in this since no one has mentioned it. Think about when you are sitting in traffic and there is little or no air movement going through your external cooler. If the external cooler is all you have to cool the fluid, then there won't be much cooling happening until you begin moving. That or perhaps a fan on the cooler would be necessary. BUT, if you run the lines through the radiator cooler, there will always be that safety net to assure the trans fluid can get cooled down granted your cooling system is efficient at low speeds.

What i see missing in the discussion is the fact that the coolant travels through the radiator before meeting the the internal trans cooler.. so the trans is not being cooled at engine temp at any rate...its being cooled to a random temp at any given time in the cooled section of the radiator.


That said how many millions of GM TH-400s lived a long life as built from GM..

So i view my approach as a enhancement on a already good thing

Personally i run my trans oil through a modest sized auxillary cooler first to knock down any crazy heat and then rely on the internal radiator to either warm the fluid up or cool it down some more.. personally i use the in radiator cooler as a method to ensure i am neither to cold or to hot as it IS possible to achieve both.. as a thermostat if you will.

This is the street section but for dedicated racing i would probably go with 1 huge external cooler

Either way will work just fine there is no right or wrong as long as you have enough surface area somewhere to remove enough heat from the trans..

I ended up just running 3/8" SS hard lines to a good sized plate cooler mounted in front of the radiator. This car will be strictly a summer cruiser and most of that will be highway. I might plumb in the radiator cooler in the future if I have no cooling problems but it will be plumbed in after the plate cooler to help stabilize the fluid temperature.

Joe.

So, how big is this "good sized plate cooler"?

B&M 70266 cooler.
size is 11" X 8" x 1.5"
Think this will work?

Pretty sure that's the same one I'm running, plumbed with 3/8" steel hard line and inverted flare fittings all the way. It seems to keep up very well with my 400 Hp 455 HO/transbraked TH400/3.89 rear gear combo on the street, running the cooler alone. I rarely see trans temps rise above 180 degrees.

http://i137.photobucket.com/albums/q...rearend062.jpg

http://i137.photobucket.com/albums/q...exhaust038.jpg

Looks to be the same b-man.
I used Swagelok compression fittings from my stash. I am a Instrument mechanic by trade.

I had space limitations on another car, had to work around an A/C condenser so I went to 2 smaller plate coolers. Figured I'd be driving this car pretty hard at times, so I wanted to make sure I would never cook the transmission fluid (4L70E with 9" 3600 lockup converter).

http://i137.photobucket.com/albums/q...t/DSC03019.jpg

http://i137.photobucket.com/albums/q...t/DSC03022.jpg

http://i137.photobucket.com/albums/q...t/DSC03018.jpg

Nice install. I will get some pictures of my install up as soon as I figure out how to post them.

My transmission cooler installation.

That looks very nice.

be careful not to place the cooler too close to the radiator or you will not get enough air flow through the cooler and the radiator. The air will stall and flow around it all in stead. not good.