Trans cooler lines

[76StepSd]

700r transmission ....anyone know if the pressure in the cooler lines is a high pressure or pretty much just low pressure lines to circulate the fluid to and from the radiator ? The way someone routed the metal lines are kinda silly. Was wondering if I could replace them with some rubber lines so I can route them the way I want . One line is routed through a frame hole and is chafing. Plus I see some compression fittings on the lines ..... Yes it looks terrible


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[LTZ C20]

Regardless of pressure, use rubber hose rated for Automatic transmission fluid, should be able to get it at most auto parts stores.

[hatzie]

I've had the parts store goons try to sell me SAE J30R7 & J30R9 fuel hose.  Don't use fuel hose its not rated for ATF temps or pressures.  Fuel hose will fail by shedding internal jacket pieces through the cooler lines.

ATF cooler lines fall under SAE J1532
The line type you want will have SAE J1532 AT or at least SAE J1532 A emblazoned on the outer jacket.  J1532 is transmission cooler hose. Suffix A = 250PSI.  Additional Suffix T is "nice to have" but not absolutely necessary.  Suffix T means high temp -20°F to 300°F.  Goodyear 652xx ATF cooler hose is 250°F A suffix not AT.  I have used Goodyear A suffix hose on ATF coolers with good results.

Don't use worm clamps they chew up the hose and will shortly leak like a sieve. 
German Fuel Injection Clamps have high clamping force and will not loosen by chewing into small soft hoses like worm clamps do.  You can get em from McMaster Carr.  They're worth every penny. http://www.mcmaster.com/#catalog/122/307.

[LTZ C20]

Constant pressure clamps work well also, I have many of this style on my truck with no issues.

These are the style GM used on these trucks new.


These are the style GM uses now.


I use the early model on small stuff like vacuum lines, pcv hoses and such. I use the newer style for fuel, transmission, radiator/heater hoses and power steering.