Picking Out a Transmission Cooler.

[crossbow]

Hey fella's,

I currently drive a Mazda6s 2003 Automatic and have begin to look into purchasing a transmission cooler for the beast.

I've noticed under extended spirited driving that the transmission starts to lose its snappy response. Of course the easiest answer would be "shoulda got a manual," but I didn't, so I must look into ways of insuring optimum performance in my automatic.

I'm well aware heat is a definite killer of a tranny, and I seem to have one of the signs that might indicate the fluid is reaching a temp which is higher then one would like.

I was wondering if anyone had any particular recommendations or brands of coolers they like to use, or have used in the past.

I'm also investing in this cooler due to the autocrossing I do with the car, and possibly track events in the future.

Like so.

The fluid thats currently being used is Pennzoil Mercon V, which is what the manual calls for.

I will be switching to Redline D4 when I install the cooler.

The designation for the transmission is a

Jatco JA5A-EL.

Its commonly found on a wide variety of imports.

Here's some photos of the current stock cooling rig in gif format.

I'm currently looking at some perma-cool maxi-cool coolers with a remote fan. Though I know the fan wouldn't be necessary normally...I do think it would be valuable while going through the 4-6 autox runs I may be seeing almost every weekend this coming summer.

Any thoughts and ideas will be most appreciated. Thanks in advance.

[ December 09, 2003, 04:58 PM: Message edited by: crossbow ]

 

[7TFord]

http://www.derale.com/transcoolers.shtml

http://www.bakerprecision.com/setrab.htm

These are two quality coolers that I know of which use AN fittings for a professional installation. I might just try the fluid upgrade you spoke of first to see if that helps.

 

[Doug Hillary]

Hi,
I would try the fluid upgrade first too as mentioned earlier.
If a cooler is not thermostatically controlled you may run the risk of an ATF running too cold!

Castrol's "Transmax Z" may be suitable ( check the specs. ) and this ATF has been known to pull 20C to 30C out of Auto trans operating temperatures. It performs best at the lowest and highest of ambient temps.

Regards

 

[Doug Hillary]

Hi,
I would try the fluid upgrade first too as mentioned earlier.
If a cooler is not thermostatically controlled you may run the risk of an ATF running too cold!

Castrol's "Transmax Z" may be suitable ( check the specs. ) and this ATF has been known to pull 20C to 30C out of Auto trans operating temperatures. It performs best at the lowest and highest of ambient temps.

Regards

 

[Garry]

I must disagree with my two colleagues below. The first link shows a tube and fin design oil cooler which is 30% less effective at removing heat than a stacked plate design which is found in the second link. The Tru-Cool is made by a division of Dana Corporation and is marketed as a "low pressure drop" cooler. This is the one I would go with. THe general rule is to go as large as you can, but make sure you have the room under the hood. Be sure to install it in FRONT of the radiator for maximum airflow.
If an Auto tranny cooler is installed properly, then overcooling will never take place. By properly, I mean have the tranny fluid go into the radiator first, then into the cooler then into the tranny. Too many people avoid the rad entirely or have it going to the cooler first and then the rad. THis does not make sense as the idea is to brind the temperature down of the ATF going into the tranny. Because it is installed "in series" with the rad, you will NEVER have an overcooling problem. With the kind of hard driving that you do, I would drop the tranny pan and replace the filter screen and have the tranny pan steam cleaned. Take a look at your debris as this will be the best indicator of tranny wear rate.

Finally, if you are one of those drivers that does not wait to come to a complete stop prior to changing direction of travel, your transmission will not last long at all and nothing will save it.

 

[crossbow]

Is their any reason why you can't bypass the radiator cooler at all? (Aka just run straight to the tranny cooler and back to the tranny).

I assume you recommend going to the radiator cooler first to ensure that the water temp keeps the tranny from being undercooled...correct?

Could you instead just run a bypass themostat which prevents the ATF from reaching the cooler until the temp's reached a particular level? (Thus allowing the cooler to be mounted further away from the radiator).

With the kind of hard driving that you do, I would drop the tranny pan and replace the filter screen and have the tranny pan steam cleaned.

The car doesn't have a servicable filter. Its actually embedded in the pan, which as you can see from the scan, is actually vertically mounted AND completely and totally unaccessible without removing an utter crapload of parts, and actually moving the engine slightly

.

I do however have a drain plug about a foot and a half from the oil drain plug. I can actually drain both simultanously with a large enough catch can. You get almost 50% of the ATF fluid out per drain.

For reference, this car has 9,000 miles on it, and has had its entire ATF fluid replaced at least once through multiple drains.

Finally, if you are one of those drivers that does not wait to come to a complete stop prior to changing direction of travel, your transmission will not last long at all and nothing will save it.

I don't quite understand what you mean by this statement.

Are you talking about shifting to reverse when your not completely stopped?

If so I always make sure I'm stopped

.

Thanks for your comments everyone thus far. Lots of curious mazda ATX owners are reading and learning.

 

[theguru]

Crossbow,

Whichever way you go, I do believe that frequent changes of the trans fluid may be necessary/ desirable considering your driving pattern.

 

[crashz]

The cooler and Redline is the way to go! Mounted in series the cooler will most certainly extend transmission life.

Doug - your comments on over cooling the fluid perplex me. Does cold fluid harm the transmission? Wouldn't an ATF and the corresponding transmission last much longer at low temps, say at 100 degrees F?

 

[Doug Hillary]

Hi,
crashZ - as you know the ATF has a very complex task to perform, gear lube, hydraulic drive, clutch pack friction device, cleaner, coolant etc etc.

As much damage and many in-use problems ( slow shifting, valve actuation etc. )are caused at low temps as at reasonably high temperatures

The heat required to actuate the torque converter "lockup" indicates a ATF minimum temperature requirement ( I suspect this is around 55C-60C in most cars ). This then is most likely to be significantly higher that the 100F you mention

Like most automotive lubricants ATFs have an optimal desired operating range. This is also a design and application issue. And of course a vehicle use issue as well

The transmission will( normally ) be set up in a particular vehicle to handle the extremes of "normal" operation but in many cases the coolant mounted ATF heat exchanger will do more warming than "extreme" cooling. Probably keeping the ATF at around normal coolant temp + 5C to 15C

The manufacturer's service manual for a specific application will give a minimum temperature for testing the operation of an Auto - this will also be its "normal" designed operating temperature

A good quality synthetic ATF will drop operating temperatures significantly and handle low and especially high temperatures more effectively than a normal semi-synthetic ATF. They will operate up to and around 120C with ease. Some are used in manual gearboxes intermittently at up to 150C for instance

At the highest extremes a supplementary cooler is mandatory for towing above a certain mass or for a specific application ( off road and etc. )

The ATF operating temperatures on my Porsche 928 S4 taken with an IR reader ( so = +/-2C or so ) over many months are;

Avg, max, min - ( celcius )

Cooler in: 59,76,43
Cooler out: 49,70,31
Ambient: 23,34,-2

This suggests that the designed ideal "normal" temperature range in this application ( rear axle mounted Auto trans )is probably somewhere between 60C-90C.
The coolant's thermostat on this vehicle cracks open at 83C and is fully open at 98C. The engine's core temperature is about 86C-88C

Personally I would always opt for a higher rather than the lower operating temperature range with components/lubricants in most automotive applications.
Others on here may of course disagree

Regards

[ December 10, 2003, 06:24 PM: Message edited by: Doug Hillary ]

 

[theguru]

Personally I would opt for the thermostat as well. We had the same concern when we fitted an oil cooler to my son's modded Nissan turbo. We went for the thermostat. You certainly can tell its working.

 

[gcubed]

i was looking at the same application on my car too crossbow. I am in the process of switiching to redline D4 and was looking at similar tranny coolers. Along with what is/makes a good tranny cooler, i was wondering, if i dont have a guage that keeps a close eye on the temp, is it smart to use a thermostat? If it fails (is there a chance it will?) will i find out too late? Thanks for all the info guys!

 

[VaderSS]

quote:

---

Automatic Transmission Fluid Oxidation
Automatic transmission fluid will provide 100,000 miles of service before oxidation occurs under normal operating temperatures of about 170°F. Above normal operating temperatures, the oxidation rate doubles (useful life of fluid is cut in half) with each 20° increase in temperature.

The approximate life expectancy at various temperatures is as follows:


175°F 100,000 miles
195°F 50,000 miles
212°F 25,000 miles
235°F 12,000 miles
255°F 6,250 miles
275°F 3,000 miles
295°F 1,500 miles
315°F 750 miles
335°F 325 miles
355°F 160 miles
375°F 80 miles
390°F 40 miles
415°F Less than 30 minutes


This information clearly shows why transmission oil coolers and the various maintenance intervals are recommended for severe usage.

Above 300°F, the metals inside the transmission will warp and distort in varying degrees depending on the severity of overheat. Because this damage occurs and fluid life is so seriously impaired, rocking out of snow, mud or sand should never exceed a very few minutes.

---

I like to use the largest capacity cooler that I can easily install directly to the condenser coil in front of a fan. I think that this mounting location, unless directly fan cooling the cooler, is more important than the type of cooler. Fin and tube coolers are larger in frontal area, for a certain capacity, but are typically thinner than the highest capacity stacked plate coolers.

I prefer the B&M stacked plate coolers with the low pressure drop bypass feature, which allows cold ATF to bypass the cooler, but in my case, I would have to reduce the capacity of the cooler, to be able to mount a B&M, vs using a larger capacity fin and tube design that would mount between the supoort struts and the condenser. Not sure what I'll eventually go with, but it will probably be a smaller B&M in conjuction with the stock oil to water and oil to air coolers. If I did not already have a stock oil to air cooler, I would probably go with the larger capacity fin and tube.

 

[crashz]

Thanks Doug,

Your comments make sense, as I've grown up with heavy equipment and know the frustrations of operating a hydraulic system in the cold.

So you are saying that a vehicle that sees light duty, no towing, and light loads, would not benefit from a cooler. In fact the cooler cold do more harm than good.

 

[VaderSS]

quote:

---

So you are saying that a vehicle that sees light duty, no towing, and light loads, would not benefit from a cooler. In fact the cooler cold do more harm than good.

---

I do NOT agree. At a minimum, buy an ATF temp gauge and see for yourself what temps you are running. OEM does NOT design the ATF cooling system for maximum life, but for the maximum economy that will get the transmission though the warranty period.

While it is possible to overcool a tranny, it is also possible to cover the cooler in the winter, or put in an ATF thermostat, though I would prefer covering, as it's less likely to fail.