Grumpy 427

For stock TH350 with shift kit. How big of an external tranny cooler do i need? car it be mounted directly to the rad on this car, or do i mount it to the AC condensor? i am looking at 18000 capacity is bigger required?

RobbSalzmann

Grumpy,

It all depends. How much motor, compression, stall speed of the converter, etc. In a close to stock car you shouldn't need one at all.

DRIVESHAFT

What are you running for a converter?
If its a stockish converter then there is no need for an external cooler.
The shift kit will actually make the transmission run cooler than it did stock.

gkull

This is what I had up front with my 700R4 I mounted it near level way up front for cooling while not moving. Staging lanes, water burn out and sitting at the lights Air would pass around it while moving. because it was so big. The 700R4 actually has brass outputs that are adapted down to 3/8ths. I changed them to 1/2 inch ID steel braided lines to and from the big cooler.

Really trick setups just place the cooler out back behind the diff. or even by the rear license plate and run a electric fan.

I have an 8X11 cooler for my power steering by the driver side vent You could put a big tranny cooler by the passenger side vent


http://www.summitracing.com/parts/BMM-70274/

jb78L-82

I have a 78 L-82 4 speed car so obviously don't need a cooler on this car. However, every automatic transmission car I have ever owned over the last 33 years has always had a transmission cooler that I have run outside of the radiator-the tranny cooler does all of the cooling! No reason to burden the radiator cooling the engine and the transmission. I have never had a tranny failure in all of those years regardless of the transmission type or mileage.

The first car I had tranny coolers on was a 73 Nova SS with a turbo 350 with 2 tube and fin coolers in the grille. I beat the hell out of that transmission which had a B&M shift kit in it and had 168,000 miles on the tranny when I sold the car in 1990, shifting perfectly. Currently, I run 2 18,000 GVW Long double stack (not tube and fin cooler which are NOT as efficient) tranny coolers outside of the radiator on a 2001 Pontiac Grand Prix with currently 110,000 miles on the crap 4T65E FWD transmission and it is perfect. I also have 1 28,000 Long double stack cooler outside of the radiator on my 94 Mustang GT AODE tranny (another beauty of a transmission) with a transgo shift kit. I recently checked the Grand Prix tranny fluid temp with an infrared thermometer and it runs about 130 degrees on a 90 degree day and the Mustang tranny temperature runs about 150 degrees on hot days. I use the Grand Prix year round in the dead of New England winters and there are no issues with the tranny not getting warm enough. It does take a few miles before it will shift into overdrive since the fluid has to be at 88 degrees before that will happen but after that it is perfect.

If you want the tranny to last a very long time, run a cooler outside of the radiator.
I have never run a cooler hanging from the radiator/condenser-it can damage the radiator hanging in that position from the weight and the vibrations! Mount the cooler separate from these two components using the brackets with the tranny cooler kit! I would mount the biggest cooler you can fit in the grille of the C3 with L brackets in the nose. Hope that helps!

Grumpy 427

yes thanks for the tips. I am bypassing the cooler in the rad due to the fittings in the rad being screwed. . So this will be a stand alone cooler.

Grumpy 427

i bought a Tru cool 18000GVW cooler.

tekvette

Not sure what size mine is but its pretty big. I mounted it up front.

jb78L-82

tekvette-that looks great! I bet that your tranny loves running much cooler with that baby on there and that was how I envisioned mounting the cooler but better. That is definitely bigger than my Long Double Stack 28,000 GVW cooler on my Mustang but being a traditional tube and fin probably is rated about the same as mine since the Double Stack coolers are much more efficient. Any idea how much the tranny temp runs with that cooler and does the engine seem to run cooler without the tranny lines heating up the coolant? Tranny fluid without a cooler can get VERY hot running through the radiator on very hot days. With traditional tranny lines running into the radiator, the tranny fluid can never get cooler than the actual coolant temperature (physics). So if your engine runs at 210 degrees on a 95 degreee day, the tranny fluid can never be below that temperature but could be higher.

TheycallmeDave

IF youre going to go stand-alone, then look at BM's plate type cooler with integral fan . I put this on my MotorHome and the Trans fluid really ran cooler.

jb78L-82

Yes, the plate style cooler is what I refer to above as the double stack cooler versus a traditional tube and fin cooler. I have found over the years if the car with the cooler has a traditional mechanical fan, an integral fan on the cooler is not necessary unless the cooler is out of the airflow path of the mechanical fan or you intend to locate the cooler in a location away from the airflow of the mechanical fan such as in the rear of the car or the side vents of a C3 as mentioned above. On both the Mustang GT and the Grand Prix above, both cars have electric radiator fans, and neither car with the tranny coolers has an issue with cooling the fluid adequately since most of the time with the car moving, airflow is not an issue and if not moving the electric fan runs consistently enough to keep the fluid very cool. Also, on very hot days, if the A/C is running the electric fans run continously. No issues! Hope that helps! On tekvette's picture above, the mechanical fan I would think would work fine for cooling if the car was not moving such as in traffic.

tekvette

Thx jb
I have not started the car yet, build amost done but when that same cooler was on my old set up (th350, 8" 4400 stall converter) it kept the trans cool for years, even on the highway, I never even changed the fluid.
The way the cooler sits now it clears the hood when its open, I dont think I could fit a fan on it the way it sits but I dont think I will need it.

...Roger...

This subject comes up on a regular basis,is it possible to run a trans too cool ?
It would seem the way GM put the cooler inside the rad that was done to regulate the trans temp to a minimum of 195.

jb78L-82

Rodger,

I am aware of that too cool concept but as stated above on numerous vehicles over the last 33 years I have never had an issue with the trans fluid running too cool to the detriment of the tranny longevity. On the 73 Nova SS that had 2 tube and fin coolers in the grille running outside of the radiator, I drove that car hard with the TH 350 tranny year round in the dead of New England winters and the tranny never had an issue. I was very easy on it when it was very cold (below 25 degrees) until the fluid got warm and changed the fluid religiously (every 2 years) and the pan was always clean as a whistle! Shifting perfect at 168,000 miles when I sold the car in 1990. The current Grand Prix which is also driven year round with the 2 double stack Long 18,000 GVW coolers is also driven year round and it will take a couple of miles to shift into overdrive when VERY cold but no issues after that. Changed the the fluid at 18,000 miles recently and it looked perfect as well as the pan. I believe that the fluid is run through the radiator on many cars simply to get the fluid warm quickly when very cold outside so that the tranny will shift normally very quickly, but at the deteriment of longevity. Remember that the number 1 killer of transmissions is heat and they will run very hot on warm days. Every 10-15 degree drop in tranny fluid will double the life of the transmission. I have run the coolers outside of the radiator on 3 cars: TH350 in the 73 Nova SS for 13 years, currently the 94 Mustang GT, and the 2001 Grand Prix. The TH350 is a great transmission, the AODE in the mustang is crap as well as the FWD 4T65E. All have performed beautifuly with the coolers outside of the radiator. Hope that helps!

gkull

Yes GM did lots of things to make them die out sooner. It was very documented that the original TH400 was so well designed that it could last a couple 100,000 miles in passenger cars. It was rengineered to fail sooner.

Our rear end yokes. They knew the ends would wear off causing slop and filling the case with metal flakes. It is called planned Obsolescence.