So I just switch from a 4L60E toa 4L80E. I just want to make sure I know which port is pressure out and which one is return.

Is the rear the pressure port?

 

the rear of the transmission is the return.. it lubes/cools the rear planetary i believe?

 

are you running the cooler lines to the radiator then to a trans cooler?

 

Yes, the rear is the return, front is pressure.

Don't forget the rear one takes a special fitting.

 

What lines are the pressure and return coming from the cooler? Which way does the oil need to flow?

 

IF your running just a AUX trans cooler it doesnt matter..
If your running it thru the radiator and then thru a cooler then it needs to go thru the radiator first, then too the cooler, then return back to the trans.

 

Yep, got the special fitting.

I want to run to the radiator then to the cooler.

What is really strange is that the 4L60E hardlines seem to be opposite of the 4L80E. I originally put the front port line of the 4L60E to the front port of the 4L80E. The rear one I cut and lengthened. But this put the outflow of the 4L80E going to the cooler first, then the radiator. Not good.

 

Good advise posted here in this thread. Just an FYI the bottom fitting on the 60E is the pressure. Not sure what you situation is but this will clarify it. I have never seen a 60E with a front or rear line or looked at it that way. Top or bottom in my book. Good luck with your conversion. Vince

 

I believe the "special fitting" aka longer fitting that you are referring to is only in the 97+ units. 96- had a shorter fitting. the fitting changed due to accommodate revised internal lube pathways.

What year 4l80e are you running?

Vince, I know a 97+ 80e will fail with the short rear cooler fitting but in case the unit is an older version, could he get away with running the longer rear "special" fitting in place of the shorter fitting?

 

No because the cooler fitting port changed location and so did the internal lube system. 97 was the first year that the rear lube and the fitting with the nipple was used.