Transmission line question

[Johnl48]

I ran my own transmission lines from Trans along frame, thru radiator support to a cooler mounted on front of radiator, bypassing radiator (as directed by my transmission guy)
My concern us there is nowhere where these lines can flex. Unlike fuel lines that have rubber hoses from frame to engine. I am concerned they will crack over time. Im Thinking of switching them to the inline tube kit that uses the steel braided flexible lines, or am I thinking too much ??

[Steeveedee]

Properly routed so that your lines don't rub on anything and have holes worn in them, you should be fine. If you live in a cold enough climate, I'd personally recommend using the radiator intercooler as a heater in cold weather. As for cracking, steel doesn't work harden like copper does. There are probably multiple millions of vehicles on the road with steel trans cooler lines.

[Johnl48]

Originally Posted by Steeveedee

Properly routed so that your lines don't rub on anything and have holes worn in them, you should be fine. If you live in a cold enough climate, I'd personally recommend using the radiator intercooler as a heater in cold weather. As for cracking, steel doesn't work harden like copper does. There are probably multiple millions of vehicles on the road with steel trans cooler lines.

So the reason he gave me to bypass radiator is that after it's up to full temperature the coolant maintains 190 degrees which he claims is too hot and will cut the life of the transmission quite a bit. Not sure if that makes sense at all. I live in NJ so it gets cold

[kwmech]

190 is not too hot----it is operating temp. Trans is bolted solid to the engine, it's going to act like a huge heat sink regardless

[bry593]

Your transmission guy is none too clever. Transmissions need to come up to temp ASAP to provide peak efficiency and minimize wear. Perhaps your trans guy can explain why OEMs use temp switches? You should have gone through the radiator and then to the external oil to air cooler. Oh well, never too late, right?

Stainless braid lines are just rubber hoses with a metal mesh sleeve. These are NOT better than steel or CuNi lines. The good news is that you appear to be using Copper Nickel Alloy, which means making lines is easy as pie! Plus they don't corrode. I'll never use annealed steel again.....

About that need for a flex joint.... Well, did you ever look at how OEMs did it? You'll notice that the lines snake around the starter (provides some axial flex) and then shoot up to the radiator at a 90 degree (provides vertical and horizontal flex). You can smash the truck into a tree and the lines will not break or leak. You will need to put a few clamps (OE work fine) to link the tubes before the 90. You don't want these lines vibrating and fatigue cracking over time.

[Johnl48]

Guess I have some work to do

[JAV6]

On my 71 I chose to run my transmission lines thru the radiator cooler and the aux cooler. Best of both worlds, brings trans temp up to operating temp and provides additional cooling. I have a fan on the aux for when I am towing and temps start to climb.

[bry593]

Be it known that if you intend to pull anything, a single air to oil cooler is insufficient. Substantial heat transfer occurs in the water to oil cooler in the radiator. This is why GM uses both radiator and external cooler on just about every 4000lb+ truck from 90's to now.

By the way, those 90's GM trucks have very nice coolers with brackets that adapt right to our 1967-72 core support. You'll find them in 3/4, 1 ton pickups as well as Burbs and Tahoes. The fittings are quick connect, but look close and you'll see these are just screwed into npt (3/8?) threads. To get them loose, heat the tube slightly with a torch and the fittings will turn right out.

These coolers are equivalent to $200+ commercial units. At the pick and pull, they cost about $20 with brackets. Hell of a deal for OE quality!!!!!

[Johnl48]

Originally Posted by bry593

Be it known that if you intend to pull anything, a single air to oil cooler is insufficient. Substantial heat transfer occurs in the water to oil cooler in the radiator. This is why GM uses both radiator and external cooler on just about every 4000lb+ truck from 90's to now.

By the way, those 90's GM trucks have very nice coolers with brackets that adapt right to our 1967-72 core support. You'll find them in 3/4, 1 ton pickups as well as Burbs and Tahoes. The fittings are quick connect, but look close and you'll see these are just screwed into npt (3/8?) threads. To get them loose, heat the tube slightly with a torch and the fittings will turn right out.

These coolers are equivalent to $200+ commercial units. At the pick and pull, they cost about $20 with brackets. Hell of a deal for OE quality!!!!!

No towing with this. This is what I'm running.
No good ?

[Steeveedee]

That should be fine, with little to no towing.

[Accelo]

As just interesting stuff;
The THM350 in Vegas didn't have any cooler or cooler lines. Just fins on the torque converter and round holes in the bell-housing.

I agreed with Steeveedee, you should be fine. Years ago I installed a transmission temperature gauge into the empty hole in the gauge cluster. If you are worried it's good to have facts.

[Davidf]

I would think you would want to go through the oil cooler first, then the radiator to ensure the oil stays up to proper temperature. So, in winter the cooler may over cool the oil, the radiator will bring it back up to 180+ degrees before going back into trans.

In the summer, the oil cooler will shed some heat before going into the radiator which will give the radiator a fitting chance to cool it down further.

Just my $.02

[Johnl48]

Originally Posted by Accelo

As just interesting stuff;
The THM350 in Vegas didn't have any cooler or cooler lines. Just fins on the torque converter and round holes in the bell-housing.

I agreed with Steeveedee, you should be fine. Years ago I installed a transmission temperature gauge into the empty hole in the gauge cluster. If you are worried it's good to have facts.

I plan in doing that. Any thoughts on a Guage that will fit and looks stock ?

[Accelo]

I used the standard 2-1/8" gauge. I got it behind the lens. It looked ok, but didn't match the stock look. Been a long time ago so no pictures.
I have converted the amp gauge to volts and that was a great look as I was able to use a newer GM gauge.

[Killer Bee]

Originally Posted by Davidf

I would think you would want to go through the oil cooler first, then the radiator to ensure the oil stays up to proper temperature. So, in winter the cooler may over cool the oil, the radiator will bring it back up to 180+ degrees before going back into trans.

In the summer, the oil cooler will shed some heat before going into the radiator which will give the radiator a fitting chance to cool it down further.

Just my $.02

this right here will keep trans temps in optimal range for efficient trans operation..

the factory coolant over trans fluid cooler stabilizes the operating temperature where the air over trans is going to have a wide range of effect depending on ambient air temp and air flow..

the objective isn't simply to cool the trans down to lowest temp possible - the objective is to prevent over heating above normal operating temp..

the aux cooler in front reduces the heat rejection effort of the factory cooler..

also consider an external spin on filter on the hot side in the frame.. oil filters better hot with less flow restriction and contamination is a trans killer..

good luck!

[dz1087]

So, I also bypassed my radiator fittings. What I did was used the steel factory lines and cut them before they made the bend up to the radiator connection and slapped on some appropriately sized rubber transmission tube to make the run up to the cooler on the front of the radiator. Made sure everything was clear and not rubbing. I also check it occasionally to ensure its no rubbing. Fine so far for 5,000 miles.