Transmission Cooler

[Yardpilot]

73 F100 351C C6. The transmission cooler is mounted directly in the center front of the radiator, snug against it. That is the sole cooling for the trans. It appears that the trans is running fairly cool, but could this relate to the intermittent cooling problems with the engine? Should I consider finding a radiator with a built in transmission cooler and run them in series? Would adding some space between the cooler and radiator make any difference? I think this radiator may be the original from the factory 240-6 three speed.

[Yardpilot]

So I guess I am not very observant. Crawling around on the gravel under the truck today, I see there are two fittings on the bottom of the radiator. No plugs. I would assume they are transmission cooler fittings. First chance I get for some downtime I'm thinking I should have the radiator cleaned and tested, including the trans cooler section, then hook the two coolers in series. Can a trans run too cool like an engine, or is cooler simply better? I really don't like that cooler being tight against the front center of the radiator like it is. It just doesn't seem right.

[squirrel]

The heat that comes out of the transmission will end up in the same place whether you have it go thru the radiator, or thru a cooler in front of the radiator, or both.

The cooler in the radiator must not be leaking, if coolant is not coming out of the fittings in the bottom of the radiator.

If you live in cold country, then it might be good to run the trans fluid thru the radiator.

THere's nothing wrong with the trans cooler being right up against the radiator, it's actually better that way, as it ensures airflow thru the cooler when the truck is not moving, since the fan will pull air thru.

[JeffMcKC]

The least air is pulled at the center of the radiator up tight it best in fact you can foam seal the edges and make it even better. The oil should be heated in the Rad when its cool to help it warm up. The water to trans fuid cooler is the most efective, the air to trans fuids are not the best at cooling, the tube ones are the worst, the stacked coolers like B&M are the most efective air coolers. If the cooling problem is intermit. and the trans cooler is in front all the time then the problem is not going to be it, its going to be a intermit part not to many move, clutch fan a sticking thermostat.

They make a Anemometer to tell you wind speeds, we use these at work to tell air flow issues.

http://www.ebay.com/itm/Digital-Anemometer-Wind-Speed-Meter-Thermometer-0-45m-s-Velocity-Bar-Graph-Surf-/270986014381?pt=LH_DefaultDomain_0&hash=item3f18066ead

[TC]

According to the guys at Yank Converters you don't need an external trans cooler until you get to a 3500 rpm stall or higher, the one in the radiator will be sufficient...... Also my friend which is Ron Davis's step son, told me just like Jeff said, there is no better cooler than the water to oil cooler in the radiator at taking heat out........ Remember just like with engine oil, trans oil needs to be at a certain temp to work properly........ You may want to get a temp gauge for the trany and see if a cooler is even necessary..........

[Deaf Bob]

See guys put air to liquid coolers in their derby cars... Problem is they have to either be under the floor or in an enclosed box..
Some even pour bags of ice in the boxes.. All those tranny lines in the cockpit scare me.. There was a guy in Montana, I think, who got burned severely when his clamps failed and sprayed him with hot tranny fluid..
We just loop the cooler lines about a foot long and run a deep sump pan on the tranny.. Fluid and filters get changed 2-4 derbys... Start to smell burnt, gets changed.
My point... The cooler in the radiator is more than likely enough.. If you pull weight on long hard hills... An external cooler might be nice

[CDMBill]

There are a number of caveats to the general rules listed above. Air flow through the radiator depends on the size and type of fans but as Jeff says the center is usually the dead spot hwen the car isn't moving and the fan(s) are running. My trans guy says the tranny really can't be too cool (unless you live somewhere where it hits zero and the car is outside) as there isn't the same kind of viscosity issues with modern trans fluids as there can be with much heavier engine oils.

And, while and while a lquid to liquid is far more thermally efficient having the trans at the same temp as the engine coolant may not be ideal. For our typical "muscle car" drag racing, cold engine, fully warm oil and a cool tarns are pretty much ideal if you can get there.

As to when you need an auxillary cooler the reality is the decision should be trans fluid temp driven. If you don't have a trans fluid temp guage, a good proxy is one of those infrared temp guns almost everybody has these days. I have to run a trans blanket and it has a very negative effect on trans temp (surprise!). I had to roll the sides of the balnket up to expose the pan to keep temps below 200 on the freeway even with the big B&M cooler. I changed to an 11"x13" Earls' which is similar to the Setrab units which dropped the temps by 20* compared to the B&M.

[squirrel]

Fluid and filters get changed 2-4 derbys... Start to smell burnt, gets changed.
My point... The cooler in the radiator is more than likely enough..

I guess it depends on how long you want the transmission to last. If it has to last a few demo derbys, then you can get away with just about anything. If you want it to last 100k miles, it's a different story

[STINEY]

Having been around derbys since I could walk, I have to wonder one thing.

I'm doubting the trans gets much beyond warmed up in the average heat. Most heats are what, 10 minutes? And how much of that is the car actually moving? 7 minutes? I know about the gear banging that goes on, but these trans are usually stone cold or next to it when they enter the arena.

I doubt much excess heat is there to dispose of. I can see your theory being sound.

But Squirrel is right too, road going higher power machines benefit from a good trans cooler.

[CDMBill]

Most of the heat is created in the converter whih is why most auto trans route fluid from the pan via the filter and pump to the converter, out of the converter to the cooler and then back into the rest of the trans. And that's likely why TC's guy says 3500 stall is a rule of thumb threashold for an external cooler beyond the radiator deal.

Thats's why you see a lot these rear mount set-ups in race cars and drag oriented street cars like Diginlif's who I stole this image from.

[JeffMcKC]

The Derby cars should have a pretty tight converter so they are not shearing off fluid. 6500 stall and no cooler wont cut it for long.

[Deaf Bob]

10 min derbys are "short " ones.. Timed the last one on pavement.. It was 19 min of half-full throttle nonstop..
The guy in Montana that got burnrd was in ICU for a week or two.. So the fluid is hot
Tranny is a 465 with the e- brake stuff removed. Basically making it a 400... Also run the 350 torque converter to get a little more stall..
I once ran 100% power punch in the motor... I'm told it rattled severely untill it warmed up... It dripped off the dipstick like water after the heat race... Years ago, there were 3 heats of 20 cars to qualify the top 6 to the finale and top 2 from the consolation heat.. Anymore there is 10 to 20 cars a night... Thus, like last weekend's show of 10 cars.. One shot for $1500..
Also the cars nowadays take more time to build if you want to have fun... Days of chain and go are few and far between...
If I could cool the trannies, I would... This works good...so far..knock wood... But if we have to do circle track stuff to qualify...I doubt we would be ok... Promotors look to fill a show...

[Deaf Bob]

The Derby cars should have a pretty tight converter so they are not shearing off fluid. 6500 stall and no cooler wont cut it for long.

That is very true...a guy ran built Mopar 400's.. Stall in the 3500rpm range, and he could not understand why his trannies take dumps, even the built ones...

[skullbucket]

I always ran a cooler out front and separate from the water radiator, lately I have been using the long two pass frame rail ones out of Summit , you can hide them way under the rad support and it get lots of air.

[TC]

The normal temperature you want your trany fluid to run between is 175 and 200...... 150 is the minimum you want to cool the fluid to and anything over 300 is death.........

Automatic transmission oil can provide up to 100,000 miles of service before oxidation requires replacement, at an operating temperature of 175* F. Above this temperature, the oil oxidation rate doubles with each 20* degrees F increase in oil temperature.

http://www.digi-panel.com/trannyoil.htm