Trans cooler recommendations
 

I've avoided installing a trans cooler because I want things to look stock, but I'm pretty sure my Tri Shield converter is heating things up a little too much as the fluid is leaking out of the overflow tube after longer drives. The fluid isn't burned or dark, but it doesn't smell fresh.

I'd like an install that looks stock-ish and clean. I'm thinking I'll have to bend a line from the outlet of the built in radiator cooler to an auxiliary cooler (mounted in front of the a/c condenser) and then another line from the outlet of the cooler that re-attaches to the stock cooler line returning to the trans.

Anyone have a clever and clean installation they'd like to share? I'm also open to cooler recommendations. Seems like a plate cooler is the way to go.

TH400 in a '68 GTO for reference.

Three ways to plumb a second trans cooler.
1. After the in-radiator cooler. Fluid is the coolest going back to the trans--which is not an advantage in winter.
2. Before the in-radiator cooler. Fluid is cooled in the summer, "heated" in the winter. Probably best in colder climates.
3. Tee'd, so that some fluid goes to one, and some fluid goes to the other. Reduces pressure in the cooler circuit.

I was thinking #1 since it never gets that cold around here.

Looking over the stock lines, they pass really close to the exhaust manifold. Wondering if that’s part of the problem.

B&M as well as other manufacturers recommend method #1:
https://static.summitracing.com/glob...er_techdoc.pdf

Auto trans fluid never smells good even when it’s brand new! Lol.

Mount brushless 12V PC fans to. A cooler with zip ties and mount Cooler to passenger floorboard. Wire fans to run off key- switched 12V.

I did and it was fine.

True. It's a second to brake fluid as my least favorite automotive fluid.

I was doing a little research yesterday and saw that Oldsmobile offered a factory trans cooler on some W cars. I don't think the pre-bent lines will transfer over to a Pontiac because of the differences in core supports, but I think I'll follow this template for and install and bend my own lines. I think I can run them under the a/c drier and not have to drill any holes.

http://forums.maxperformanceinc.com/...1&d=1699371415

http://forums.maxperformanceinc.com/...1&d=1699371420

I run the biggest coolers I can fit, bend my own steel lines and hide the cooler up front where it can't be seen. The only clue is seeing one of the trans lines from the radiator disappearing under the core support and going to the front, and another line running to the back along the stock routing with the other line.
If done properly one really has to look at it and pay attention to even detect an extra cooler.

The Olds diagram you found gives you the idea. Modify as you see fit ;)

The larger stacked B&M cooler as in this reply is what I use.

It looks like the B&M supercooler line is either going away or in the process of being rebranded as Holley. There's no inventiory at Jegs and Summit and the Holley site only lists a few items. I was looking at a Derale 9000 series fin and plate like this one: https://www.summitracing.com/parts/der-13615

Yep I've used more than a couple of those. They work nice and the 1/2" NPT allows you to convert to 5/16 inverted flare fittings for factory steel lines if you care to bend your own. That way there are no hoses, no hose clamps or any of that type of "potential failure" stuff.

A couple of different trans cooler installations on my 1964 GTO and Tempest. Hopefully you can get some ideas on how to install one on your 1968 GTO.

Large B&M plate cooler on the GTO running a TH400/10” Continental converter:

https://forums.maxperformanceinc.com...6&postcount=27

Twin small B&M coolers on the Tempest running a 4L70E/9.5” Yank 3600 lockup converter:

https://forums.maxperformanceinc.com...d.php?t=608230

Thanks for digging this up. This is pretty close to what I'm after, only it will go through the radiator cooler first.

I'm looking through Summit and having trouble figuring out what adapters I might need. Seems like I need to go from a 1/2 NPT on the cooler to an inverted flare 1/2-20 on the 5/16" tube but I can't find a direct connector that does that in the catalog. Looks like you combined a couple adapters to make it work. Were you able to find the brass connectors and adapters at your local hardware/auto parts stores?

Sometimes it's easier once you have the parts in hand.

http://i137.photobucket.com/albums/q...7.jpg~original

The best place by far was my local NAPA store, they had a huge selection of brass inverted flare fittings and pipe fittings.

You can buy your steel brake line tubing there as well. Any leftover unused fittings can easily be returned for a refund, brass fittings aren’t cheap nowadays.

I think I figured out what I need to make this work. If not, I've got a NAPA on the other side of town and a decently stocked hardware store down the road.

- Derale 33604 (9.750 in. x 10.625)
- 1/2x20 Inverted flare nuts for 5/16 tubing
- 5/16 steel hard line (steel hardline lengths from the parts store would work too)
- 1/2in NPT to 3/8in NPT reducers
- 3/8in NPT to 1/2-20 inverted flare adapters
- 1/2in x 20 inverted flare union (for the return line)

I'll figure out what I need to mount it to the core support when the cooler gets here.

Time to dig out the tubing bender and flaring tool!

I ran 6AN braided stainless lines and used these fittings for my radiator.

https://www.yogisinc.com/product_search/?q=GS231102

Received the cooler today. The good news is I ordered the right fittings. The bad news is that I was very optimistic about what would fit. Between the a/c condenser, horns, hideaway components and hood latch support I've got a very small area to mount this thing and there was no way that 9.75" x 10.625" was going to fit. I see why HIS put his on the floorboard.

However, I think I can get a shorter 9.75" x 6.25" x 1.25" plate cooler to fit. The thickness of the plate cooler is limiting because it hits the hideaway components and horns.

The other option is to get a tube cooler which is 1/2" thinner. That would give me a little more room to go taller, but I'm thinking a shorter plate cooler would be more efficient than a taller tube cooler in terms of heat dissipation.

Nope...

https://forums.maxperformanceinc.com...1&d=1699575584

Maybe...

https://forums.maxperformanceinc.com...1&d=1699575163

Kinda why I went with two small coolers, packaging restraints caused by the air conditioning condenser.

This is my 69 bird which has Vintage Air - initially it was up against the condenser but I ended up spacing it out for better air flow. The cooler is a B&M 70266 (11x8”)

On the air condition cars I've always been able to mount the cooler up front behind the grill with room to spare, at least on the A-bodies anyway. I just have to get a little creative and make some mounting brackets (I like my coolers floating and not mounted against another radiator or condensor) That way they are front and center with good air flow in and around the cooler.

While everyone was watching football, I spent my Thanksgiving in the garage. It took me a little bit of trial and error but I ended up getting the cooler mounted. The Derale 33602 (9.75 in. x 6.25in) is a little on the small side, but it was as big as I could fit.

I originally tried to mount the cooler closer to the center of the car near the hood latch/horn bracket with the ports facing the passenger side.There wasn't enough room to run the lines with the headlight vacuum canister in the way, so I flipped the cooler so the ports faced the driver side and mounted it favoring the passenger side. I made little L-shaped brackets out of stock steel to mount it to the underside of the core support. I bent new steel lines that run between the a/c drier and core support and run along the bottom of the a/c condenser.

I thought I could bend the tubes in one piece with no splices, but I couldn't fish the lines around the radiator so I ended up splicing them under the condenser. I cut the factory return line right before I bent up to the radiator and spliced in my new return line from the cooler similar to how it's shown in the Olds diagram above. It looks a little clunky to me, so I may go back and see if I can refine it. The length of tube I needed for the clamp on the flaring tool limited how short I could make my tubes after the bends. I also probably need a couple tubing mounts to secure the new trans lines.

I discovered that I had my cooling lines installed backwards on the trans. The top line on the radiator was going to the bottom port on the trans and vice versa. That might have been part of my problem, so I fixed those when I put everything back together.

Anyway, here's where I ended up.

https://forums.maxperformanceinc.com...1&d=1700788447

https://forums.maxperformanceinc.com...1&d=1700788221

https://forums.maxperformanceinc.com...1&d=1700788244

https://forums.maxperformanceinc.com...1&d=1700788560

https://forums.maxperformanceinc.com...1&d=1700788576

Nice job - looks good - onto the next project!

Wow are you a plumber by-trade...looks perfect

Definitely not a plumber. I bought a coil of 25 feet of tubing from Summit and I have about two feet left. Like I said - A LOT of trial and error.

Nice work.

Playing with hard lines can be quite a challenge and you did a great job of it. :thumbup:

WOW Nice installation.

GT

Wow! Very nice plumbing work Ken!

Dennis

Old, but a good thread. Nice pictures and installation.

After reading it I'll revive a subject often not touched upon, the operating temperature...

I noted this information from B&M in the link from post #4:

"Monitor the transmission fluid as the fluid leaves the cooler and returns to the transmission. Monitoring the returning fluid will give you an accurate indication of how efficient your cooling system is functioning.
A good operating temperature of an automatic transmission is 160º to 200º F as the fluid exits the cooler."

And also noted from B&M was the optional use of a cast deep oil pan for the transmission that can increase capacity allowing more cooling ability.

And then from this source, they state 150 degrees is considered the 'minimum' ideal operating temperature.

https://mechanics.stackexchange.com/...erating%20temp.

Rhetorical questions and something to consider...

How many actually install a transmission oil temperature gauge and monitor it ? Can you use a trans oil cooler that is too big ?

I've used a larger size Earl's stacked plate cooler before (company link below) and considered it a bit large for my application, but also noting I ran an aftermarket deep pan with the extra capacity.
Often the transmission oil temp only ran a tad over 100 degrees when cruising around on the open road. The temp sending unit was located in the pan on the transmission.

https://www.earls.com.au/product-cat...oling-systems/



.

The temp question is a good one, I’ve always thought it makes sense to have a thermostat setup for all your coolers. Same reason the coolant system in your engine has one: faster warm up, getting to optimum temperature.

ATF seems to be but more forgiving, but I’d assume that the engineers designed the transmissions to function at a temp close to engine temp. The viscosity of ATF is of course quite a bit different at 50* compared to 100* compared to 200*.

I plan on using one of these for my C20:
https://www.haydenauto.com/en/produc...y-pass-coolers

Not what I'd expect. I'm not in a position to challenge B&M, but I'd have expected 170--200 in the pan, not in the cooler return-tube. Many modern cars have transmission temperature sensors on the valve body in the pan; the info is available to view using a scan tool, including cheap "dongles" that plug into the OBD2 connector.

It is entirely possible to over-cool the fluid with a too-huge transmission cooler.

Keep in mind that these vehicles had a maximum load rating--vehicle weight plus towing weight--and GM was prepared to warranty the transmissions with--in most cases--only the in-radiator trans cooler. Even if GM was playing the odds, and going cheap on transmission cooling, I see guys adding monster transmission coolers to daily-drivers and thinking they're doing some good when in fact the transmission fluid never gets to operating temperature.

Where the temperature is being measured. Excellent subject.

From the internet, this is stated. But no mention of in the pan or not.....

"In a perfect world you want to keep auto trans fluid temperatures between 175 and 200 degrees F, although I wouldn’t panic with a real-world 150- to 225- degree range.
You don’t want to lean on the trans below 150 degrees, any more than you’d lead-foot a cold engine."

Similar but here it states where the temperature is measured:

TRANSMISSION TEMPERATURE MEASURED AT OIL PAN OR SUMP:

150° F= The minimum operating temperature. Note: It is possible in low ambient temperatures to overcool the transmission with auxiliary oil to air coolers.
Oil to water coolers in standard factory radiators will normally not overcool a transmission.

175-200° F= Normal pan oil temperature operating range.

275° F= Maximum allowable oil pan temperature for short durations during long hill climbs.




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Highest temp measurement location is the line out to the cooler. That is taking the oil coming out of the converter and sending it to the cooler. When I had a gauge on that line, the hottest I ever saw was about 225F. TH350 with 10" continental, 3.90 gears in 100F ambient summer day while driving in town. It would get hotter in town than it would during a outing at the dragstrip.

Installed a transmission cooler on my 1995 Lincoln Towncar 12 years ago (other 2 vehicles are manual transmissions) that came with a fan. Totally bypassed the radiator and have an adjustable fan thermostat in place. 99% of the time, the fluid never gets hotter than 140F. Zero problems. I only had the fan come on twice when I was stuck in traffic for hours with outside ambient temps over 100F with the a/c running. I think I have the fan set to 160F.

I noticed an immediate and significant change on how the transmission shifts with the cooler in place. When the engine would get up to normal operating temp, the fluid would hoover around around 205f and the trans would shift rougher from the fluid thinning out due to heat. With the cooler in place, the trans always shifts butter smooth regardless. At 30K miles, the fluid still looked brand new which was not the case before the cooler.

Installing the cooler also relived the engine of additional heat. If I'm going down a hill, I can watch the engine temperature drop down, even during the summer. Before the cooler, that never happened, even going down the Donner Pass in the middle of winter.

Is there a downside to routing the lines like option #3 ?

Not my first choice in winter. Otherwise, no, not really.

Maryland gets all four seasons so it seems each configuration has its plus/minus. I drive my cars spring/summer/fall - so 90 degrees to 40 degrees temps

Very cool! Heheh! I bet InLine Tube would bend those for you, they just did a deep resto on a W-43. But guess you already are going in another direction.

.

They do sell these lines pre-bent with a cooler, but the Olds core supports and front end structure are different enough that I don’t believe it would work on our cars. It’s also pretty expensive for what it is. There are much better coolers available for less. It did serve as a nice template for my install though.

https://www.inlinetube.com/products/inl10428

My trans guy is dynamic racing trans in north Branford Ct
They build amazing transmissions. ( can’t say tranny anymore has a whole new meaning these days) but they want me to keep that thing cool as I can. I actually pulled it apart 2 times after about a year use at the track 140 track passes. That year. It was so clean and so new looking inside no heat marks anywhere we put every piece back in as it was and been running it all this time. I had been worried about heat because of how that gauge was reading it’ll bury that gauge , but the converter temps tell a different story but they said you couldn’t keep it cool enough.

So they’d be ok with the temps being below 150- assuming you could get it that low?

I wouldn't be. I'd want 170--200-ish. Newer cars go hotter, they don't even turn on the electric cooling fan(s) until 210 or so.

Mine never gets above 140F bypassing the radiator. I have started and driven it in below zero weather with no problems. If the temps are freezing or cooler, let the trans warm up a few minutes. The engine will need to warm up a few minutes before driving, anyway.

My bird has a 4l80e with a tsp converter, auxiliary trans cooler and the cooler in radiator - stays between 160-190 normally.

Transmission temps not engine temps.

Heat kills transmissions , cold doesn’t
Why would it?

Trans fluid doesn’t thicken like motor oil.
There’s no reason why a cool (let’s face it we aren’t talking cold at 100 degrees. ) transmission would be hurt by that temp?

When we fly airplanes we wait for 100 degree oil temps to do our run up. 1700 RPM w prop torque on it. And that’s an engine with aircraft oil in it .

Keep in mind these airplane engine max RPM is 2600 drop dead max.

Yes. Transmission fluid in the pan at 170--200 ish. Newer vehicles can be warmer than that, since the radiator isn't fan-cooled until 210 or so, so even the "cool" tank of the radiator--where the trans cooler lives--is going to be plenty warm.

My 2019 GMC trans fluid never gets that hot even when towing.