[SRR]

Originally Posted by chiphead

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.

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.

[Cobrabill]

Originally Posted by SRR

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?

[Pontirag]

Originally Posted by Cobrabill

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.

[cutlas]

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?

[Fat Cat]

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.

[Formulas]

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..

[cutlas]

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.

[Old Goat Racer]

Originally Posted by cutlas

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"?

[cutlas]

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

[b-man]

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.

[cutlas]

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

[b-man]

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).

[cutlas]

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

[cutlas]

My transmission cooler installation.

[rohrt]

That looks very nice.

[Pontirag]

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.