trans fluid in collant==== trans cooler in radiator

just to expand on the issue why you have a trans cooler mounted in the radiator....
The concept here is: There are extremes of temperature.... hot and
cold. When the temp is hot the trans fluid would need to be cooled...when temp is cold trans fluid would need to be heated..
Obviously hydraulic fluid / transmission fluid and others have a operating temperature range where they perform best and maintain their respective operating properties for the longest period of time. You exceed the operating temperatures in either direction you are going to have performance problems... fluid breakdown, hard part failures due to fluid issues...etc..
I'm talking about extremes in ambient temperature.... transmissions have to function in sub-zero conditions as well as 100+F conditions. Some times you need to cool while other times you need to heat. With the trans cooler mounted internally it gives the ability to cool and heat....and hopefully maintain the trans fluid within its operating parameters.
If you live in the south generally you'll be most concerned about cooling the transmission in the summer..... ie you live in the north you'll be concerned about the fluid reaching the operating temp ....
the interaction between the radiator and the trans cooler allows a good compromise between the two conditions. hot / cold.
Since the trans cooler on most automatic cars in built into the radiator and is basically surrounded by coolant you have a built in very effective manner in which to control the temp of the trans fluid.
nothing is perfect and you certainly can improve upon the cooling ability of the OEM factory trans cooler, but also consider why they put the cooler there in the first place... it both heats and cools depending on what the weather condtions are...how much load is being placed on the engine/trans... etc....
More to the picture than just slapping on a cooler and saying thats it.
--
Elbert Clarke
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I think the radiator has nothing to do with warming up tranny fluid. I've been in the north and drove when it was 40 below. Yes, the tranny fluid was cold, but it warmed up long before the radiator did. The function of the radiator is to cool the fluid - nothing more. Just my 02. . . . .. .

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Since I can't find anything in writing to back up what I said about the coolant in the radiator being used to heat the trans fluid in cold situations my comments to that may be inaccurate. Its my belief that its used for that purpose , but as far as I can tell thats just my opinion.
From the books I've looked at, all comment as to the cooling purpose of the "trans cooler" which is a given. So unless I find something in writing stating otherwise I was wrong to state as fact that the trans cooler in the radiator is used to heat the transmission fluid.
wrote:

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Elbert Clarke
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. . . . .
I think the radiator has nothing to do with warming up tranny fluid. I've been in the north and drove when it was 40 below. Yes, the tranny fluid was cold, but it warmed up long before the radiator did. The function of the radiator is to cool the fluid - nothing more. Just my 02. . . . .. =========== ========== snipped-for-privacy@noway.com (Doc)
You're right. The AT heats up the ATF just fine without the help of the coolant. Doc ========== ========== Here's my theory....and it is only a theory, Keep in mind....I lived just outside Chicago for only 3 years....the rest of my poor life has been spent in the south....so I don't have a great range of cold weather experience to justify a damn thing....just comon sense.
but here goes......
If yer ass lives in Antartica.....you better run the darn thing through the radiator, if no other reason than to BE SURE that your viscosity is some kind of stable...
Granted....tranny's operate optimally at somewhere around the 180 degree mark.. now this is an optimal figure.......all sorts of bull dung could be added into the equation that could throw it off a few degrees higher or lower...but...most all transmission literature will give you a mean temp of 170 to 190 degrees Farenheight as the optimum temp for performance........which comes down to viscosity.
As Gary stated....that convertor sitting there at a stop light is generating 100% slip on its clutch....creating an arse of heat....we could throw the random red-neck into the eqaution, sitting there in drive with his foot on the brake knocking back a 6 pack of Budweiser while he's talking to his hunting partner...who's sitting in his truck doing the same thing.
How's all that heat getting dissepated in a Hayden oil cooler that is mounted out of series with the radiator?
An oil cooler that's mounted "stand alone" style......HAS TO HAVE AIR FLOW across the surface in order for it to do it's job....
That engine fan isn't going to pull enough air through that Hayden cooler to do the job..... the radiators cooling surface is a heck of a lot larger than a tranny coolers, and the radiator has a fan shroud to make the air pull through it's surface...unlike the cooler. I guess you could always install an electric fan in front of the tranny cooler....but shit... why not buy the radiator and get it over with.
There's the argument that heated tranny fluid takes away from the radiators abililty to cool the engine coolant. I'll not deny that. But a bit of research is sure to prove that the design of the radiator takes that into consideration.
Consider this....newer transmissions are designed not to go into lockup OR overdrive untill the transmission reaches "hot mode".
Now.....let's say you live in MN where it's liable to get somewhere around -20F. It's not hidden knowledge that transmission fluid DOES TURN TO GEL.....you can name any temperature you want for it to do it at... personally...I think minus 20 degrees, jumping into the truck and taking off on down the hyway with a 45 mph windblast on the ole Hayden cooler ....might jest do it.
As a test....you could always stick a themometer in the grill and check it after about 5 minutes of driving....windchill is one thing I do remember from living up north for awhile.
Then again...you can sit there and let the truck warm up for 10 minutes or so, in drive, with your foot on the brake, while you freeze your arse off waiting for the heater to work. Personally.......I'll let the trucks natural fluid heat transferr system do the job for me.
I'm not trying to change anyones mind on the subject of not installing the cooler inline with the radiator. But.....I think a lot of you are really not thinking this thing out very well.
The facts are...that extreme cold affects viscosity. Transmissions are designed to operate with a certain viscosity of fluid. If you eliminate the radiator, especially in cold weather, the temperature of the fluid IS going to be affected dramatically.
I have dropped transmission pans on trannies that have sat overnight in below freezing weather....and let me tell you... the word SYRUP is not an exageration.
below are a few links....bother with them or not....this is only a sample of what's available on the net.....do some google time and you will definately find out more on the topic.
respectfully,
NubbsMcFarkle ~:~the last link in the list is for Gary..... a pre-hire sheet to give prospective employees~:~ . == Products - Transmission - Hayden Address:http://www.mobiletek.net/hayden.html Changed:5:17 PM on Friday, May 11, 2001 === MDV Synthetics - Independent AMSOIL Dealer, Andover, MA Address:http://www.mdvsynthetics.com/actionnewsarticles/viscosity.htm === SwRI Automatic Transmission Technology Section Project Briefs Address:http://www.swri.org/atts/projbrf/fluid/torqloss.htm ==== Automatic Transmission/Transa|Multiple Choice Address:http://wps.prenhall.com/chet_halderman_autotech_2/0%2C6601%2C516115-%2C00.html ========== ==========
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exactly right
the torque converter has a minimum of 8% slip.........so that 8 % gets converted to heat
at stall (sitting stopped at a light) it has 100 % slip
slip = heat

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