Ok, this question is not for my '02 Z28, but for my Dad's '73 Camaro. The car has a TH350 tranny in it, with a ~2800 stall, currently running the oil lines to the rad and then to an external tranny cooler as well (think it may be an 18,000 gvw cooler? ).

Anyways, we've been having troubles keeping the engine cool, so my Dad just bought a thick aftermarket aluminum rad for the car (hoping this helps? ). BUT, here's the question: the new rad is just a straight radiator (for a manual) so there's no built-in tranny cooler. Will just an external cooler be sufficient to keep the tranny cool?? If so, would the 18,000 cooler be enough, or should we at least step-up to a 24,000? Or how about a pair of ~18,000 coolers?? (because I don't know if 2 24,000 coolers would even fit in front of the rad? )

Does/has anybody run an automatic with just external coolers?? What do you guys suggest?!?!

T.I.A.

 

We always suggest that the trans. be ran "in series". The water in the radiator is a much better cooling medium than just plain air. The lines should be ran through a stock radiator first, and then an external cooler...Unless it's a dedicated drag car.

Frank
CPT

 

I installed a TH400 in place of my T56. Naturally, the Griffin aluminum radiator did not have a trans cooler. Solution was to install a Perma-Cool fan assisted trans cooler. More than adequate on a setup that's capable of pulling 800lb-ft on a 5,000rpm flash stall, off the line. I can get you the model number if you need it. On my 4th Gen, its installed in the drivers front fender, where the filter from a cold air intake would normally reside.

 

Thanks Fred. Maybe we'll look into that.

Now to further expand the question, if we had a temp gauge off the tranny, what temperature should the fluid be running, and at which point in the system?? (send/return??)

Thanks again .

 

Hoping you don't mind a less than professional answer. I just installed a trans temp gauge and B&M 24000 cooler. The sensor goes in the lower line that also happens to go into the bottom of the radiator. I cut the rubber section and inserted the sensor there but you will need to run a ground wire from the sensor to a ground. I used the transmission line itself for a ground by simply soldering a wire to the line and clamping the other end to the sensor body.

The cooler will tap into the other line coming out of the top of the radiator. This is the return line.

As for cooling from the radiator; if what I just watched on the television is correct on how things are made, the transmission cooling line for an automatic's radiator is a straight through affair. In other words, the transmission fluid goes in one side and directly out the other. No twists or turns. I could be quite wrong about this but that's what was shown. So, by adding a transmission temperature gauge and installing the best (stacked plate) cooler you can find will out perform a radiator cooler and you will be able to watch it.

According to B&M the magic number for transmission fluid is 240 f degrees. That is the temperature where varnish is formed on the internals. 260 and clutch slippage occurs. 295 and things begin to warp and at 315 the fluid becomes carbon and the tranny is toast.

 

Thanks. So you're saying (which makes perfect sense) measure the temperature of the fluid coming directly from the tranny ... obviously, this makes sense, you want to know how hot the TRANNY is and not the COOLER!! Gotcha.

Now you're saying 240* is the "magic number", but is that the number to STAY AWAY from??? (methinks so! ). In that case, what do you guys normally strive for, or see on the tranny temp gauge?? ~200*? ~180*?

Keep in mind this is a 1973 Camaro, ~425 HP 350 SBC, TH350 tranny w/~2800 stall converter (that sees mostly w/e cruising, but occasional track duty).

 

Someone on here said his or her cooler keeps the tranny around 170-180*F. Plenty cool. Don't know if they had a stall, or not though. Mine seems to be doing a good job. I do not have a temp gage, but the cooler does not get hot enough to the touch so it works for me.

EDIT: Found it here

 

Beauty ... thanks muchly!!!

I'm still curious if anyone else has run a typical cooler only setup, and if you had any problems??

 

Hey Fred, I was checking out those Perma-Cool fan/cooler units (http://www.perma-cool.com/Catalog/Cat_page13-1.html) but looking at it, it's really nothing more than a good size cooler with an electric fan blowing continuously across it. SO, this leads me to thinking ... we currently have an electric fan setup on the '73 that came from a '96 LT1. Now I'd like to think that while cruising, there should be enough airflow through the cooler/rad to keep everything happy? But do you think that running one of the electric fans (with the cooler positioned inline with it) would be enough to keep the fluid cool while stopped/idling/driving slow in stop-and-go??? And are the factory fans on a 4th-gen capable of running for extended periods of time without burning out?? (I'd like to think so?!?)

I suppose we may just have to install a temp gauge though, see where things are at, and then go from there?

 

My answer was scattered but essentially everything you wrote is spot on. The fluid is the hottest coming out of the converter. The fluid in the pan is called the running temperature and it will not be the highest temperature.

Since we're talking different transmissions, you need to insure you would be tapping the correct line for temperature monitoring. This is achieved by putting the transmission under some load and feeling for the hottest line. I know in my case, this takes some time but when everything is at operating temperature, just moving the car around in the driveway brings the transmission temps up quickly.

As for using the cooler alone, the pro answers in the above posts agree with what's on the B&M cooler instructions. It is best to use the cooler in conjunction with a radiator implanted cooler but the instructions take into account exactly what you describe. A radiator for a manual transmission being used in an automatic conversion or an HP application. The recommendation is to use a larger and/or fan cooled cooler. Since I can imagine a lot of room in front of the radiator on a 73 Camaro, you might be able to apply a much larger cooler than a 4th generation with the radiator behind a tilted airfoil. My cooler is roughly 11" X 5.5" X 1.2" thick. They make them larger and if you have the room, I would think you can get away clean that way. Having a trans temp gauge with the sensor in the right place will verify your safety or otherwise.

Just be sure to use the stack plate design and not the fin on tube.

If it were my decision on my car, I would go for the larger cooler with a gauge without replacing the radiator but monitoring temps closely and see how it goes. From everything I have read, the stock cooler in the radiator does a meager job. An 11" X 11" X 1.2" cooler has many times over the cooling capacity of the in-radiator cooler but your 425 hp with higher stall takes things to a different level.

 

Yeah, there's certainly lots of room to work with!! Surprisingly, it wasn't hard to find the "room" to put a cooler on my '02, but it was just a b!tch trying to get the zip ties through the electric fans, the rad and the A/C condensor. I think I only got 3 out of 4 (the 4th one was impossible to get, and I didn't feel like ripping apart the car and pulling the fans just to get 1 more zip tie, which at that point didn't seem necessary anyway ... the cooler felt good and solid ).

...but back to the point, there's lots of room in front of the rad on the '73, so if we end up going with a bigger cooler, and/or a dedicated fan for the cooler, it won't be a problem making it fit (I'm beginning to lean towards installing a temp gauge though, then there will be no question how things are looking).

 

Sorry to be-labor the point but I think what you are up to is what I would be doing as well.

I gauged my car before and after the cooler install. The gauge would go slightly above 200 in light traffic before the cooler. Now it doesn't go over 175. The word I heard was dropping 20 degrees doubles the life of the oil and transmission. It's just what I've been told though....

I only have two of those tie connectors going through my radiator / condenser. They are impossible to apply through the top holes without dismantling something and the cooler would basically ride where it is without anything holding other than the hoses. An accident would pull it forward but bumps and vibration aren't moving it.

One last time on this - look at the stack plate design over the fin on tube. Everything I've read recommends them.

good luck and if you can, post your temperature results.

 

I have a trans temp sensor that's mounted in the side of the TH400.... not sure what temp it reads. When the car is being driven, the airflow, even with the cooler not mounted in direct air path and the fan not running, will keep the temps below 200degF. With extended periods of idling, the temp will start to creep up, and I have a manual switch for the fan.
A thermostatic controller would be easy to hook up, but its not driven much on the street, so its seldom an issue.

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