Trans Cooler Questions

[HugrOrang71]

Needing to buy a trans cooler for a newly rebuilt T-350. Has a stage 2 shift kit and a 2K stall converter, behind a mild 350 (maybe 300 hp). The cooler that was on the truck is a tube and fin design 1"x 11"x 8", which was used along with the stock radiator cooler.
Would it be better to use the same setup with a new cooler, use a larger cooler with the radiator, or completely bypass the radiator and go with a larger external cooler?
What is the performance difference between the stacked plate and the tube and fin coolers?

Any recommendations or thoughts are appreciated.
Thanks,

[cdowns]

it's better to use the radiator and the aux cooler, with the fluid first going thru the aux cooler then the rad because especially during colder weather the tranny works best with warm fluid . it can cause a problem having the fluid too cold. the tranny fluid thru the rad is to keep it at the optimum temp forproper operation

[Low69CST]

Originally Posted by cdowns

it's better to use the radiator and the aux cooler, with the fluid first going thru the aux cooler then the rad because especially during colder weather the tranny works best with warm fluid . it can cause a problem having the fluid too cold. the tranny fluid thru the rad is to keep it at the optimum temp forproper operation

I've heard the exact opposite. Cooler the better. Through the radiator first to knock it down to the engine temp and then through the aux cooler to knock the tempature down even more.

[72MARIO]

Low69 is right about the cooler the better for a summer/fair weather driver. The shop that built my tranny said if it was a winter driver that it might be a good Idea to run it thru the rad to get it up to tempature faster and to keep it warm on the -20 days. I have the biggiest B&M ttranny cooler you can buy to cool my 700R.

[cdowns]

Originally Posted by Low69CST

I've heard the exact opposite. Cooler the better. Through the radiator first to knock it down to the engine temp and then through the aux cooler to knock the tempature down even more.

yeah well you ain't in oregon

[72MARIO]

I should say by running it thru the Rad into the external cooler the tranny fluid becomes a consistint (sp) temp.

[CHEVIBUBBA]

i've never found a minimum operating temp for any auto.
could be out there but, your not going to get it cold enough to hurt it no matter where you drive it.
cooler is definately better because the killer of auto's is HEAT!
& contaminants.
keep it clean & cool.
i have the LARGE b&m cooler as well.
one safe statement is:any temp below 180 is acceptable.
one statement you will never here:the tranny was ruined because you ran it too cold.

[71-longbed]

cdowns .. what does Oregon have to do with anything ??

[cdowns]

you've got colddd weather and you'dwould benifit you haveing warm tranny fluid, doesn't it snow there in july and stuff???

[Big69C20 Toy]

so you guys know colder tranny fluid costs HP... yes you heard me. the differences for cold fluid vs. normal operating temp are significant... i've done testing on this (cant really release info)

There are optimal ranges for a tranny, and yes HOT kills but cold is harder to turn and can also cause a tranny to puke.

For optimal cooling go throught the radiator first to get the largest cooling effect/consistancy, then to the external cooler/fan setup... never hurts having an additional filter & temp guage for the trans too
Good luck

[Low69CST]

Originally Posted by cdowns

yeah well you ain't in oregon

You aint in Kentucky! I just never heard of problems being caused because of tranny fluid being too cold. I have noticed them to be a little sluggish going into gear when cold, but never a problem. It gets down to 0 or below here in the winter and 105 in August. We put the biggest coolers on we can.

[CHEVIBUBBA]

Big69C20 Toy;how significant?
if your research has shown a number at or less than the margin of error of the dyno it isn't reliable.
at least with the rpm's we typically turn.
tranny fluid is designed to maintain viscosity thru out it's designed operating range.while it may not fully acheive this objective, it comes pretty close.
done a viscosity test at different temps?
& going thru the rad cooler?what if the engine coolant is at 220?
not gonna transfer much heat unless the tranny temp is at 240 or up.
& if the tranny temp is below the coolant temp it will work in reverse!
adding heat to the tranny fluid.
no thanks. the torque converter is a great fluid heater all by it's lonesome.
the oem's did the rad cooler to save money & actually heat the engine coolant for faster warmup.

[HugrOrang71]

Well, it has snowed here in July, but it isn't a regular thing.

I know that there is an optimum temperature for engine oil, but I've never given much thought to ATF. From what I understand, the viscosity of ATF is more stable and consistent compared to engine oil. I did some searching and found a couple of recommendations on minimums:

from Baumann Engineering:
If you could keep your fluid at 140°F that would be ideal. Most transmission fluid works best at this temperature. In actual application keeping the temperature this low is difficult. Try to keep your fluid temp below 190°F. If it gets to 230°F or higher for any period of time you should start looking for a place to pull over and park for a while.

from TCI Automotive:
The ideal operating temperature for automatic transmission fluid is between 175 and 225* F.

But, if you talk to 10 people, you seem to get 10 different answers.

I've always heard that going through the ext cooler and then through the radiator is the best method as there is less heat transfer between the coolant and the ATF which helps engine temperature. Did a test on a friends rockcrawler. Changed the cooler plumbing so that the ext cooler was first, and actually lowered the engine temperature about 20* F, and didn't affect the temp or the performance of the transmission. Also found that there is ALOT of heat transfer between the transmission case and the engine block. By lowering the transmission temp, it significantly lowered the engine temp.

Still looking for suggestions on a size and mounting location...

[Big69C20 Toy]

I'm not allowed to discuss fully what i've done... but in regards to how drivetrain interacts with the motor, fluid temp of the trans and engine make large differences when coasting etc and do 'drag' on the vehicle when trying to accelerate.

I fully agree a cooler trans is good, but too cold <60F and the viscocity of fluid gets thicker, though i know trans fluid is about the best fluid there is for COLD (<-30F) and still maintaining function and then coming to temperature well.

For any normal operating conditions you're not going to have any issues with stuff being too cold, just on those frigid mornings when your vehicle has been outside and is way cold... the initial fluid losses are up there ~20%+ in the driveline when you are doing coasting and such... but like i said things warm up pretty quick and that isn't much of an issue any more.

Hugr: the idea of keeping that trans cooler and helping the motor sounds very logical, since a trans case is aluminum (much better at dissipating heat) and is connected to the back of the block...

As for the best configuration for cooling oil,trans,engine i'm still thinking it's mostly vehicle configuration dependant.

Too cold an engine isn't a good thing (actually not good at all=greater innefficency) so there is a fine line between the good and evil worlds of heat here.
rock on

[smokekiki]

I am running a B&M cooler.The trans shop and B&M recomend the cooler after the stock cooler.

[StingRay]

If it's going in a daily driver around here you run it through the external cooler first. In the winter with temperatures that get to -40 and colder the wind chill value at the grill opening can get unbelievably cold. Think -40 with a 70 MPH wind. That would have to be at least a hundred below zero. It's just too cold. If you don't think too cold can klill a tranny visit a tranny shop around here when it gets REAL cold and they'll convince you otherwise. For those in the sunny south it's probably fine the other way.

[CHEVIBUBBA]

Originally Posted by Big69C20 Toy

I'm not allowed to discuss fully what i've done... but in regards to how drivetrain interacts with the motor, fluid temp of the trans and engine make large differences when coasting etc and do 'drag' on the vehicle when trying to accelerate.

I fully agree a cooler trans is good, but too cold <60F and the viscocity of fluid gets thicker, though i know trans fluid is about the best fluid there is for COLD (<-30F) and still maintaining function and then coming to temperature well.

For any normal operating conditions you're not going to have any issues with stuff being too cold, just on those frigid mornings when your vehicle has been outside and is way cold... the initial fluid losses are up there ~20%+ in the driveline when you are doing coasting and such... but like i said things warm up pretty quick and that isn't much of an issue any more.

Hugr: the idea of keeping that trans cooler and helping the motor sounds very logical, since a trans case is aluminum (much better at dissipating heat) and is connected to the back of the block...

As for the best configuration for cooling oil,trans,engine i'm still thinking it's mostly vehicle configuration dependant.

Too cold an engine isn't a good thing (actually not good at all=greater innefficency) so there is a fine line between the good and evil worlds of heat here.
rock on

true the fluid does create drag as does any & all drivetrain parts.
question is how much power is lost from between say 180 degrees vs. 80?
is it 1%? 1/10th of 1%? 10%?
unless testing on a high quality, calibrated dyno has shown a repeatable power loss, larger than the margin of error in the dyno, due to low trans fluid temp & no other causes, the data is flawed.
if dyno testing has shown a large power loss due to low trans fluid temp it may only apply to the tranny tested, etc.

as for size & location;
i highly recomend mounting an elec. fan on the biggest oil/tranny cooler you can get.
then mount it under the bed on the passenger side at an angle to promote airflow while in motion.ie:the top should be forward with the bottom angling away to the lower rear.support the cooler by means other than the line connections or it will start leaking.
with the fan mounted on top of the cooler.
this will allow the fan to pull,(most efficient), when at rest.
where ever you put it, DON'T mount it in front of the rad/condensor.
it will decrease the airs' ability to cool the rad/condensor dramatically.
from a aerodynamic standpoint it reduces the pressure differetial across the rad/condensor.what air makes it to the rad is hotter.
from a balance standpoint;it adds weight to an already forward biased weight imbalance.