Factory lines or braided line?

[duey_roc]

I'm getting ready to replace my tranny cooler because the 1/4" bent lines coming from the transmission aren't the same size as the barbs on the cooler, therefore it leaks. Should I keep the bent lines I made? Or switch to braided line? I would love a connection other than hose clamp and barb. I really want AN fitting but I'm not sure how that would happen.

 

[jbc426]

I'm getting ready to replace my tranny cooler because the 1/4" bent lines coming from the transmission aren't the same size as the barbs on the cooler, therefore it leaks. Should I keep the bent lines I made? Or switch to braided line? I would love a connection other than hose clamp and barb. I really want AN fitting but I'm not sure how that would happen.

Factory lines are 5/16". The fittings at the transmission and radiator are smaller and thus more restrictive than GM or Ford. Are the barbs permanently mounted on there, or are they removable? If they are removable, you can get better fittings or even use adapters to run from the flared end of your transmission line into a NPT threaded adapter that has an NPT thread to screw a barb type fitting on the end of your hard line.

You want the transmission fluid to slow down through the cooler to some degree to allow it time to shed it's heat. A small line into a large line and back to a small line does just that. Only a portion of the transmission fluid is pumped out to the cooler at any given time anyway.

You are running it through the radiator first though aren't you?

 

[67Dart273]

You want the transmission fluid to slow down through the cooler to some degree to allow it time to shed it's heat.

Sorry, this is an oft repeated "factoid." The problem is, "it's wrong." Heat exchangers just don't work that way.

 

[pishta]

I would run steel OEM style with stock flare style fittings, nice and clean. Get yourself a tube bender and some premade 5/16 flare fitted lengths and go to town. Braid always sags, gets nasty dirty and inevitably ends up touching something its not supposed to.

 

[pishta]

Sorry, this is an oft repeated "factoid." The problem is, "it's wrong." Heat exchangers just don't work that way.

Bingo, "....For most fluids in most applications; a LOWER tube velocity means a lower inside heat transfer coefficient therefore the HEAT TRANSFER IS LESS EFFECTIVE, so thermal designers will typically try to keep the velocity as high as the tube material and pressure drop will allow..." Look at it this way, the longer the fluid is backed up in the transmission waiting in line to be cooled through a low velocity heat exchanger, the hotter its going to get, and the hotter the trans will get, bad. You really want the fittings to be the same ID as the exchanger tubes so you have a system that has its smallest ID in the least controllable variable, the tube size in the exchanger for maximum volume and efficiency.

 

[nm9stheham]

If you have to use braided, use teflon lined line. It will stand the oil and heat; the rubber will degrade and you cannot see it doing so due to the braid. Rubber braided also can have pins holes in the rubber that can seep over a long time.

Exposed steel line is also a small help in cooling the fluid.

 

[pauly]

Are we getting into turbulent flow versus non-turbulent flow aka Reynolds numbers??

 

[nm9stheham]

Sorry, this is an oft repeated "factoid." The problem is, "it's wrong." Heat exchangers just don't work that way.

Right on....the fluid inside is in constant contact with the inside of the cooling tube, so the heat transfer does not change with flow rate (unless it cavitates); heat transfer only changes with the inside and outside temps. With slow flow, the fluid will cool as it moves through the exchanger, and will transfer less heat at the middle and far end of the exchanger and thus less heat on average gets out. The fluid coming out of the far end may be cooler but the overall heat transfer is normally less with slower flows.

Edit: And yes, let's go on into the Reynolds numbers! I am sure I will learn something....but I have to go get something useful done right now...

 

[pishta]

laminar, non turbulent. If you know the velocity of the fluid in the stock 5/16 line, you can figure the Reynolds number. But we are not talking steam speeds, just lazy low pressure hydraulic fluid. Take a cooler line off, It doesnt spray like a water jet.

reference?
[ame]http://aip.org/tip/INPHFA/vol-2/iss-4/p18.pdf[/ame]

 

[duey_roc]

Factory lines are 5/16". The fittings at the transmission and radiator are smaller and thus more restrictive than GM or Ford. Are the barbs permanently mounted on there, or are they removable?

You are running it through the radiator first though aren't you?

The transmission cooler I bought is just a standard Hayden oil cooler. The barbs are what's on there and it's what I have to use. I replaced the radiator with an aluminum radiator, and it doesn't have the automatic transmission cooler built into it.

 

[zijmer]

The transmission cooler I bought is just a standard Hayden oil cooler. The barbs are what's on there and it's what I have to use. I replaced the radiator with an aluminum radiator, and it doesn't have the automatic transmission cooler built into it.

you dont need to go through the rad. just staight out to the cooler. you do want to use the largest line possible. in your case, 5/16 is it. we like to use coolers made by long, same as b&m, maybe made by the same company. they have whats called a low pressure drop incorperated in it meaning they wont impeid flow in extreme cold like we have here north of the "49th". also some of the cheaper brands of aluminum coolers, the kind that has a tube that snakes back and fourth with multiple bends covered in fins acually slows the flow down.