Transmission Cooler
 

Hello all,

I'm looking to improve my transmission cooling ability. I've got a 4L80e with transbrake and 3500 converter in my 68 firebird. I rarely use the transbrake as the car is 99% street driven. I'm currently running the internal radiator cooling loop and intent to continue using it but add an external cooler.

In my research it seems that the theme is get the biggest cooler you can fit. The Tru-Cool 40K cooler seems to get good reviews but it's rather large. In any case I'll go with a plate style cooler.

The heart of my question is, if going with a large cooler in front of the radiator, do I risk impacting motor cooling? What are you all using? Any suggestions for mounting/fitment in first gen F-Body?

Thanks much for taking time to read and respond.

at minimum you are going to send a portion of preheated air thru your radiator with an independent trans cooler in front of it. you may see some efficiency from removing the current tranny fluid cooling capacity out of the radiator however, not sure how to quantify that. not sure how big that tru cool 40k is but you may be able to mount it off to one side where it does not obstruct the air going to the radiator. On my 64 i have a B&M plate style (12''x8''?) off to the passenger side and, and use the brake and have not had any trans failures, but to be fiar i have no idea what my trans temps are. I only know that the cooler off to the side has not effected the cars performance. I am going to be using that car on the street a lot more in its next renditon so only time will tell.
are you experiencing high temperatures now? a lot of users are puttin their coolers under the car or even toward the rear, and using the small fans to cool the fluid. might be something to consider if you have real estate.

I used a long/narrow stack plate and mounted it in the valance with some brackets I made using sheet steel.

It's still going to block some air flow, but it's not slammed right against the radiator.

You don't need to go too big with the stack plate coolers, they are much more efficient than tube & fin ones.

EDIT: I run thru the rad then the cooler, 4L80e, lockup set at 53mph, and it's kind of a loose converter. The cooler docs stated it's good for at least 30 degrees.

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I have always used a basic stack plate style cooler mounted in front of the radiators. Usually something around 12" x10" or there about. The size depends on what I'm working on and the room I have where I want to mount it I typically make brackets and mount it behind the grill somewhere, not up against the radiator.

I've never had any adverse affects on engine cooling on any car.

I run them all the same way, through the engine radiator first and then through a trans cooler, back to the trans.

2 of the cars have 4l80's so I can easily monitor trans temps. From what I've seen they run about 20 degrees cooler than the engine does.

I use a medium size Hayden plate cooler thats just like the B&M, installed in lower left area in front of radiator, 500+hp stroker motor with a 3 row Champion radiator, car runs at or under the 180 T stat in all conditions including summer 90+° temps or back to back passes at the drag strip witting in staging lanes.

All companies of aux coolers suggest running them with the rad cooler but after it for street cars, the more efficient rad water to fluid cooler takes the majority of the heat out (or adds some in cold weather) then the less efficient air cooled aux cooler removes whatever it can, and requires air flow to work. Heres a chart showing how to route it and some ATF temp data.

I run large coolers on almost every old automatic car I have. Usually I'll run it like how you described, running it thru the radiator before looping out into the large aftermarket cooler, although I have been experimenting with running the trans cooler separately from the radiator.

In either case, I have never seen a rise in coolant temp due to a massive trans cooler. The only time I've experienced a slight rise in coolant temp is when running a massive front mount intercooler.

Some really great ideas. I thank you all. I especially like the idea of a wider and lower profile cooler. Space is a bit limited but putting it lower and closer to the lower valance openings may be a better option.

Should be able to make something work using the center support, there's a few options to make it work.



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There is a lot of space to locate the cooler, I went a little higher so the airflow from the grille opening hits the cooler, the lower valance opening is very thin and wouldnt provide as good of air flow. The normal radiator mounting with the supplied plastic push pins works great, the cooler is very light weight and doesnt stress the rad rows at all, been in use for 10+ years with no signs of any problems, makes mounting anywhere on the rad or AC condenser very simple.

I thank you. Wanting to be sure there isn't some critical concern with size of cooler and proximity to the radiator which might impair engine cooling. It seems the theme is get the biggest one you can fit. There is a lot of space directly in front of the radiator. Just want to be sure I don't make matters worse.

Fantastic, thanks for the photo as well.

The Level 1 version of Silver Sport’s A41 (4L60E) transmission installed in my '70 GTO is rated for 450 lbs. ft. of torque and does not require the use of a dedicated auxiliary trans cooler (so they say). Units rated for higher torque values do. However, the cooler Silver Sport recommends or that would be included with the higher rated units is the Hayden model 404, which is the old-fashioned tube and fin design. These units use the nylon retaining strips that you poke through the cooling fins of your radiator. Well, I wasn’t willing to poke things through my new $700 radiator, so I had some decisions to make.

Everyone knows that the trans “cooler” contained in the radiator serves to both bring the trans fluid up to temperature quickly using engine coolant heat as well as shed excess heat back into the coolant should the trans be running hotter than the engine. Remembering that the GTO left the factory with a 190* thermostat explains why the recommended trans fluid and filter service interval was every 20K miles. Currently, the GTO has a Stant™ 180* thermostat. That plus the extra capacity of the new radiator helps to keep the engine between 180* to 190* during most summer days even with the AC on. Only occasionally have I seen 195*

According to the B&M trans cooler recommendation chart, the ideal max temperature for transmission longevity is around 175* to 180*. There is also such a thing as too cold too. When trans temps are consistently below about 140* the thicker fluid viscosity strains the fluid pump and doesn’t protect the internal moving parts as well.

I decided to use an external auxiliary cooler in addition to the standard loop through the car’s radiator. My goal was to have a system that got the trans fluid up to temperature quickly yet maintained that temperature during all ranges of use. To do this, I chose to include an oil thermostat to limit fluid flow out to the external cooler until it was hot enough to need the extra cooling.

The cooler I chose was the Hayden 698, which is rated at 23,000 BTUs for pickups, vans, towing up to 5,000 lbs, class “C” motorhomes, or travel trailers up to 24 ft. Overkill? Probably, but I figure that the excess capacity would be adequately throttled by including a Derale oil thermostat in the plumbing.

The thermostat starts to open at around 160* and is fully open at 180*. This arrangement lets the engine radiator heat up the fluid quickly while the thermostat only bleeds hot trans fluid out to the auxiliary cooler as necessary. The result is that the 4L60E’s fluid temperatures run in the 170* to 175* range during normal cruising (monitored via the Hughes Trans Controller Bluetooth app). It does this even on the hottest days with the AC on - just the result I was looking for.