Transmission Oil lines

[blazing816]

Okay I searched and couldn't find what I was looking for, and I am going camping soon and want to get this project done before then. I am installing an aftermarket transmission cooler to my truck for towing purposes. I have read a bunch of debate about running the cooler before your after the radiator built in trans cooling.

But my questions is does anyone know what the standard size thread is on the transmission oil lines to the radiator. I do not want to just clamp the rubber hose on the flared hard line, I really want to do it right and get a flared threaded to hose barb fitting. None of the box auto parts store can tell me what the thread is and I have tried two different fittings and none have fit.

So if anyone know the correct thread please let me know. Or if you have done this and have a part # of the fitting you used. Thanks in advance.

[bd]

Radiator wet cooler thread is 1/2-20 inverted flare.

Use bulkhead fittings to pass through the radiator support, so the lines don't chafe.  What style cooler are you using; threaded or hose barb?  There are various approaches to cooler installation.  What do you have in mind - quick and easy or ?

[blazing816]

The cooler has barb fittings on it. And I want to do it right, but do not want to spend a crap ton, because it is on my beater until I get my other one restored. But I do tow 4500lbs about 3-4 times a year and trying to make sure my trans does not die on me.

[bd]

What size hose fit the cooler barbs?

[blazing816]

3/8" push-on barb....is what box says.

My next question is should I bother getting an inline trans temp gauge or just wait and put one in the pan after my camping trip?? (I really do not want to put new pan on week before big trip, cuase will not have time to make sure it does not fail.)

Or is it accurate enough to put it in the service port on a TH350 (seen some talk on the internet about that)??

Thanks

[bd]

Proper hose routing is from the transmission - past the temperature gauge sender - into the radiator wet cooler - then onto the supplemental dry cooler and back to the transmission.  The gauge sender should be immersed in the fluid flow between the transmission and wet cooler inlet rather than in the transmission case or pan.  Your primary interest is in the working temperature of the fluid exiting the transmission, which represents actual transmission heat production or waste.  When the temperature sender is inserted into the fluid flow, the driver receives immediate feedback of realtime changes in trans temp, which can forewarn of developing transmission trouble.  However, care must be taken so as not to install the sender such that it impedes fluid flow.

According to Hayden Automotive, automatic transmission life doubles for every 20° F drop in transmission fluid temperature.  Automatics enjoy their greatest service life when routinely run below ~180° F.

Some installers go so far as to place a redundant sender in the outlet (return) side of the coolers to monitor cooler effectiveness.  The gauge can then be flipped back-and-forth between the two senders using a toggle.  Redundant senders aren't really necessary, but satisfy curiosity. 

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As previously stated, there are many approaches to line routing.  Here is just one option:  Layout and install two 1/4" NPTF x 3/4" bulkhead fittings (pictured) through the radiator support.  Then install two 1/4" NPTM x 3/8" barbed 90° elbows into the front of the bulkhead fittings for the dry cooler hoses.  When installing the new dry cooler, do not install the hose barbs pointing down - this prevents air from being trapped inside the cooler and maximizes heat transfer.  Route and secure the hoses through Adele clamps to keep them from chafing and away from the hood safety latch. 

On the backside of the bulkhead fittings install two 1/4" NPTM x 1/2-20 inverted flare fittings.  Connect the dry cooler line that returns to the transmission to one of the bulkhead fittings through a 1/2-20 inverted flare union and a double flared 5/16" steel brake line of the appropriate length.

Connecting the "outlet" of the radiator wet cooler to the bulkhead fitting requires a little more ingenuity.  Procure a 5/16" double flared steel brake line that is sufficiently long to connect between the inverted flare bulkhead fitting and the radiator fitting. 

• Notice that the radiator is mounted in rubber cushions.  The 5/16" steel line MUST BE LONG ENOUGH that you can bend a double pigtail into the new 5/16" line between the radiator and the bulkhead fitting to allow for radiator movement (look at the brake lines that attach to the master cylinder for an example).  If you don't incorporate the pigtail into the 5/16" line, you run the risk of breaking the line at the fitting and possibly damaging the radiator tank!

Alternatively, you can use rubber hose or AN hose with the appropriate fittings instead of steel line.

[blazing816]

so would these work if I want to go straight from hard line to rubber hose and rubber hose to radiator wet cooler.

http://www.summitracing.com/parts/hda-393

You talked about 5/16-20 inverted in your last post, but originally you said 1/4-18 inverted. Just making sure buying correct adapter.

[bd]

You're right - that's what happens when I type with my elbows.  It should have read 1/2-20 inverted flare as I originally stated.  I went back and corrected the errors.  Thanks for catching it and letting me know.

The 393 Hayden fittings you linked should work.  Although hose size isn't stated for the fittings, Hayden coolers are generally 3/8" barbs, so the fittings should be equivalent.  If you decide to use rubber hose all the way through instead of the bulkhead fittings, be sure to secure the hose and protect it from rubbing, cuts, etc.

[blazing816]

No Prob, thanks.

Now I just have to figure out if I want to buy a gauge and T-fitting and all fittings and go all out and on my beater truck or just install the cooler and know that it is better then stock (which I really have not had any problems that I know of yet).