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What size trans cooler do I need?

26K views 19 replies 7 participants last post by  xntrik 
#1 ·
Have a 4500 stall converter with a th400 transmission. Has a trans brake and engine is pushing 597 flywheel hp with an additional 300 shot of nitrous at about 6500 rpm. Rear end ratio is 3.73. What size trans cooler / what gvw cooler do I need, thanks.

Brandon
 
#4 ·
84Z said:
Have a 4500 stall converter with a th400 transmission. Has a trans brake and engine is pushing 597 flywheel hp with an additional 300 shot of nitrous at about 6500 rpm. Rear end ratio is 3.73. What size trans cooler / what gvw cooler do I need, thanks.

Brandon
I am curious what the car will be used for.

A trans Brake valve body operates the trans at a high main line pressure. This heats the fluid up besides the heat from the high stall speed converter you have.

If the car is street driven much , a larger cooler will be needed. At the drag strip only, a smaller cooler could be used.
 
#5 ·
it's for a 84 camaro street/strip car, mostly street, any idea about what size gvw would be good, or should i just go for one of the biggest they have like 24,000 gvw? Is overcooling a problem or is it fine? Thanks, and sorry for the noob questions, never dealt with automatics before. Thanks.
 
#6 ·
84Z said:
it's for a 84 camaro street/strip car, mostly street, any idea about what size gvw would be good, or should i just go for one of the biggest they have like 24,000 gvw? Is overcooling a problem or is it fine? Thanks, and sorry for the noob questions, never dealt with automatics before. Thanks.
Just be sure to use a bypass thermostat... They are only about $ 20 and prevent the trans from getting too cool when operating and make it warm up quicker when it is cold.. you can use the radiator cooler if you want to. I like them for warm ups.

What's the big deal here.. Hasn't anybody ever heard of one before????
Has anybody ever seen a rusty trans dipstick from too cold of oil???
 
#7 ·
xntrik said:
What's the big deal here.. Hasn't anybody ever heard of one before????
Has anybody ever seen a rusty trans dipstick from too cold of oil???


No , I have not.

With the 4500 rpm stall speed converter and a trans brake / full manual shift tranny he says the car has, I doubt the tranny running too cold will be a problem
 
#10 ·
red65mustang said:
you do need to know what is the temp now.... as xntrik asked in the first post to determine cooling needs

best advise I can give with no temp info: phone the tech lines at Hayden, B&M, etc. and ask what size they recommend....they may know from experience
If you use a big cooler and the thermostat I suggested, the temperature is irrelavent.
 
#11 · (Edited)
To answer a PM here:

Yes I have seen a rusty dip stick above the oil level because the oil was staying too cold and the condensation not being evaporated from the ATF. And it was Mobil 1 ATF. Sure the real cool oil is good for parts.... but the water is NOT.

The thermostat splices into both of the lines. When the oil is cold the output oil from the trans is routed directly back into the trans bypassing all cooler function until the thermostat opens the path to the cooler. That makes the transmission warm up faster and maintains a minimum operating temperature just like an engine radiator thermostat does.

Just like an engine coolant radiator, the size of the oil cooler and the airflow across it determines the maximum trans oil temperature.

Contrary to popular belief, the best place to put a transmission cooler is behind the radiator..... between the radiator and the mechanical fan. = Lots of airflow in all conditions and does not increase radiator coolant temperature.

check out site www.readershotrods.com drag cars/georges
 
#12 · (Edited)
xntrik, Ha! you got me,

weird....? B&M offers and recommends the same bypass thermostat for their oil coolers.....don't say anything about using it with their tranny coolers

(edited from $20)...$40-60 to know the oil is not "too thick" on a cold day......good plan

(xntrik, $20 if you fab your own ???....just messin')
 
#14 ·
Until this thread- I have never seen or heard of a transmission suffering from being too cold either, and exactly how were you made aware your transmission fluid WAS indeed not warm enough to evaporate moisture out of itsself? This would be more of a problem in Canada, than Arkansas, and then limited to the cooler months of the winter.

All irrelevance aside the subject here is not enough cooling and what is a figure to go by for enough?

You cannot accurately go by the GVW rating put forth on most of the coolers sold by nearly everyone who sells aftermarket coolers.

A rough generalization is still only a guess, but if you intend on running street with that and want to keep a better eye on it a- transmission temperature gauge with the sensor mounted in the transmission pan would be the BEST starting point. Several threads here on Hotrodders have indicated the pan is THE BEST source of transmission fluid temperature for accuracy. Only after you know how much over the optimum 175(f) degree temperature you are, can you make the most effective purchase of cooler for YOUR particular needs.
 
#15 · (Edited)
M&M,

Typical cooler will lower the fluid temp anywhere from 80 to 140 deg in series with the radiator depending on the ambient temp/amount of air flow (vehicle speed)/gpm of fluid.....not hard to be "to cool" on a cold day

Agree a $50 guage is worth the money because ATF viscosity (thickness) is so sensitive to temp changes:
kenetic velocity@ 40*C (112F?)=36
kenetic velocity @ 100*C (212F)=7.5

(and now to prove I'm crazy)
Don't have a oil/tranny temp guage...use a turkey oven thermometer ($5?)...the trick was a hand full of plumbers putty and aluminum foil on the steel trans oil line to get a good "ballpark" reading....175*=beef well done!

xntrik, thanks, the bypass thermostat (on my xmas list) beats hell out of my 2 coolers in parallel in summer, 1 in the winter plumbing mess!
 
#16 ·
trans cooler

Thanks for all of the great info on the bypass for the trans cooler, I have never heard of one either. I also had not considered the moisture problem in the trans from running too cold. I have seen many tubes that are rusty, I just never put two and two together! That's why I love this board, I always learn something new. I also appreciate the different opinions and view points that others have.

Does this mean that the placement of the aux cooler either before or after the radiator cooler is over!? Or is this used when only using the aux cooler?
 
#17 ·
Ricky Rocket said:
Thanks for all of the great info on the bypass for the trans cooler, I have never heard of one either. I also had not considered the moisture problem in the trans from running too cold. I have seen many tubes that are rusty, I just never put two and two together! That's why I love this board, I always learn something new. I also appreciate the different opinions and view points that others have.

Does this mean that the placement of the aux cooler either before or after the radiator cooler is over!? Or is this used when only using the aux cooler?
The thermostat completely bypasses everything past it. All it does is loop the output line into the input line.

As for how big a cooler is needed. That is a guess in any situation. Go the biggest you can fit and afford. Use two in series if you want to. The principle is like a big engine coolant radiator. The thermostat maintains the minimum temperature, the radiator size limits the max temp. If you have plenty, then the thermostat will keep it warm enough.

To answer your question: Why put heat into the radiator coolant if you don't need to?

OR..... leave the trans go through the radiator tank and then install the thermostat on the output line using it to connect an aux trans cooler. If radiator cooling is not a problem... that is what I do.
 
#20 ·
M&M CUSTOM said:
Until this thread- I have never seen or heard of a transmission suffering from being too cold either, and exactly how were you made aware your transmission fluid WAS indeed not warm enough to evaporate moisture out of itsself? This would be more of a problem in Canada, than Arkansas, and then limited to the cooler months of the winter.

All irrelevance aside the subject here is not enough cooling and what is a figure to go by for enough?

.
Recapping: I mentioned that the dipstick was rusty above the oil level.

Yes it was Little Rock, Arkansas, in the Spring, and the severe rust showed up in a week! One time it wasn't there, then it was!

It was on a Ford high performance 2.3 turbo AT that came with a factory aux cooler after the radiator tank, and I had added another cooler in series.

After mentioning this, I found a couple other hot rodders that had experienced the same thing. So we all went thermostats.
 
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