Nomad78SA

I have a modfied motor as stated in my signature and have put in a 700R4 transmission from Bowtie with a 1800 stall converter. the question is, should I install a trans cooler? If so, where at and what kind?
I know they help out but do I really need to put one in. thanks for any responses for I know little about transmissions and stall converters.
Neil in Tenn

79er

Yes. Anytime you can reduce tranny temp do it. The cooler the trany is the longer it will live and plus the less power it will use. :D For location the local racing trany gurue put mine on the bottom left corner of the radiator so it just misses the hood when I open it.

89formula

you should definitley invest in one with a modded motor. just be sure you don't mount the cooler inline with the one in the radiator.

Smokehouse69

You betcha Neil,
Heat is what kills a transmission over the long run. A good cooler will add many thousands of miles to your tranny.

Cajun99

The original owner installed a cooler on my car's TH400 many, many years ago and it still shifts tight, doesn't leak and the fluid stays a nice clear bright red.

The car has never been out of the deep south so I think I'll leave things as they are :D

Nomad78SA

OK, I agree coolers are a good thing. So where do you mount them at? I would guess it would be in front of the readiator so the heat could disapate. My car has AC, so would I mount it in front of the condensor coils? Has anyone got pic's of how they mounted them? So, do you run the cooler lines in seiries with the lines to the trans cooler n the radaitor or some other way?
I am starting to put in my transmission lines and cooling system so I want to address this now before I install the body back on the frame.
As always, Thanks for the help
Neil in Tenn

mrvette

For decades now i have put a LARGE tranny cooler in place of, not in addition to, the engine radiator factory unit....I mount them behind the a/c condensor coils allmost exclusively, down low, and tied to the a/c coils...
IF I could run any auto tranny at say 50f all the time, I"d do it...colder the better, shifts better, last longer....be sure to use double clamps on hydraulic rated hose, fuel line hose no longer works....used to, years ago, but not anymore....dunno why...someone changed something...

GENE

Cajun99

Mines mounted horizontal to the pavement over the center opening of the lower valance and cools in series with my radiator. I'm not sure where everyone else has theirs.

I was a little concerned about it blocking too much air to the radiator being mounted in the center hole when I bought it but I've since found that it's not an issue. The car runs cool even with the AC on in traffic.

89formula

bypass the radiator completely.

BSeery

Uh, why not ??

The best install method is to have the transmission fluid come from the tranny to the radiator cooler, then from the radiator cooler to the add on transmission cooler and then back to the transmission.

The radiator cooler knocks the temp down some and then the fluid goes to the additonal cooler for even more cooling.

Allan71

I would do it the other way around. From the tranny to the aux cooler, then to the factory radiator cooler and then back to the tranny. This way the tranny fluid will usually run the same temp as the coolant temp, and you won't run the tranny too cold in the winter as the fluid leaving the aux cooler could be heated as needed to maintain the proper temperature. This is the same procedure that GM used on the original RPO KC4 Engine Oil Cooler which used engine coolant to either cool the oil if it was hotter, or heat the oil if it was colder to promote quicker oil warmup and reduced wear.

nunus79

The reason I heard was that if the radiator internally leaked into the tranny cooling line, by the time you would notice it, the water would have farck up the tranny.

BTW, I run mine with both radiator & auxillary cooler in series.

The Dude

It's probably one of these, "couldn't hurt" deals. That converter is just about stock stall spped so you shouldn't really be building up the kind of heat that'll REQUIRE one. But it wouldn't hurt to install one.

On My '76 there wasn't really any convenient way to mount it in front of the radiator--there wasn't any "good" way to get th lines around the core support. Sooo, I ponied up for a larger one and mounted it inside the shroud on the back of the radiator. I drilled holes through the top and bottom of the shroud for the lines.

And, like some others, I kept the factory stock cooler functional. My fluid goes from the tranny, to the radiator, to the aftermarket cooler and then back to the tranny.

Good luck to you.

BSeery

Winter cooling is not an issue where I am. I cool mine down to the coolant level, and then cool it even more with the additional cooler. But like you said, it winter, that may be too much.

Luckily I don't have that worry.

lars

Allan71 is correct:
When I worked with GM at the Salt Lake Training Center (mid '70s), we actually did testing of aux trans coolers. We (GM) installed aux coolers in 50 Salt Lake taxi cabs, and compared the results against cabs without aux coolers. The cabs with the coolers got 4 times the life/mileage out of the trannys than the ones without. No joke.

As for installation, we did a bit of research on this, too. We found that the aux coolers are best installed in-line with the stock radiator cooler, and the aux cooler should be installed before the fluid goes into the radiator cooler. This does 2 things: First, the aux cooler knocks quite a bit of heat out of the tranny fluid, and thereby prevents the radiator from having to absorb this heat. This runs radiator/engine temps cooler on hot days, since the tranny fluid entering the radiator has already been cooled. Second, on cold days, it is actually possible to run the tranny fluid too cold. If the tranny fluid drops down below 120 degrees, its lubrication and flow properties are not conducive to good tranny life - just like running an engine with cold oil. Running the fluid through the radiator after the aux cooler "tempers" the tranny fluid on cold days, and aids tranny warmup and performance.

A side note: Don't run rubber hoses or flex lines. Tranny cooling lines run at very high pressures and volumes. Hard-plumb everything with inverted flare fittings and flared tubing lines. There's a really good reason why the factory goes to the trouble of doing their lines this way. I've personally seen the results of running rubber cooling lines on the tranny, and it ain't purdy....

89formula

i don't see how running tranny fluid through a little spiral cooler inside an already hot radiator and then through an auxillary cooler is better than running it through a cooler dedicated strictly to trans fluid. different strokes for diffeent folks.

flynhi

How about a tranny cooler with an electric fan? Thenyou could mount it anywhere.

lars

89-
I think you read it backwards.... you don't run the fluid through the radiator first - you run it through the aux cooler first for the reasons explained in my post above. We published an SAE paper on this system and principle, and it is the generally accepted engineering practice for installing aux coolers on street driven vehicles. Race cars are a completely different matter, as cold-weather operation, warm-up times, and transmission longevity are not essential factors, so you can run a stand-alone cooler and bypass the radiator. This is not a good idea if you're running a daily driver car for the reasons explained.

fly-
In the testing we did, we found that you don't need a lot of airflow across the aux heat exchanger in order to produce significant reductions in tranny temp and improvements in tranny life, provided the heat exchager is installed in a location out of direct engine and radiator heat. The taxis we installed these systems in were running in stop-n-go traffic. The coolers were installed in front of the radiator/condenser assembly, and did not benefit much, if any, from the engine fan due to the gap between the tranny cooler and the condenser. They saw ram air at elevated speeds, but little airflow at low speeds. They still had a remarkable effect on tranny life.

theandies

Lars -
Someday, I may convert my 4-speed to and automatic (so my wife can enjoy the car, she knows how to drive a standard but she can't handle the clutch I put in it), If I do, then will a trans cooler be all that I need? I don't want to change the radiator because I just spent $500 on a brand new one. Its funny, I was just thinking about this today...its weird how you start thinking about things you may or may not do to your car and then get on the forum and find a new post on the topic.
John

lars

theandies-
The problem with installing just a separate tranny oil cooler without running it through an in-radiator heat exchanger is temperature control. By running the tranny oil through the radiator after the external cooler, you effectively get your engine's cooling system thermostat to control the tranny oil temperature: if the tranny oil gets too cold running through the aux oil cooler on a cool morning, the radiator brings the oil up to temp and "moderates" the oil temp a bit. This promotes good oil flow, good viscosity characteristics, and long tranny life. The radiator acts as a thermal "buffer", stabilizing tranny oil temps and keeping the tranny oil always within an acceptable range. Tranny fluid that is too cold will do as much long-term damage to an automatic as excessive heat: the higher viscosity cold oil will not engage the clutches as quickly as oil at the correct temperature and viscosity, and this results in clutch slippage and wear with every gear change.

If you just run an external cooler with no radiator heat exchanger, you can actually run the tranny oil too cold on cold days. On very hot days in stop-n-go traffic with inadequate airflow across the aux cooler, the temps can get too high. There are temperature control systems you can run with the external cooler, but the cost of procurement and installation for good compoenents will be very close to the cost of an auto trans radiator. If you're going to use the car as a weekend/daily driver on the street, the in-radiator cooler is a very safe, reliable way to go - especially with an aux cooler installed for the tranny fluid ahead of the radiator. If your wife is going to be driving it, ease and reliability is the key....

lars
former instructor at the GM Training Ctr - Salt Lake City
certified in TH350, TH375, TH250, TH400
self-taught on Powerglides... :)