[78w72]

Originally Posted by punkin

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.

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.

[punkin]

Originally Posted by 78w72

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.

Fantastic, thanks for the photo as well.

[LKLusza]

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.