Ok I need to plumb in new transmission lines for my NA 3800 series III swap and have a couple questions.
The Stock fiero lines are a smaller line corect? My lines were replaced on my car before I owned it and they used copper tubing I will have to measure to see what size was used.

What size should I be using is it 5/8" for the 3800?

Will I need an adapter to attach the larger line to the stock Fiero Rad? I plan to add a in line transmission cooler (the kind you add in front of the rad) should I go through the external cooler first then into the Rads built in cooler or go through the rads cooler then into the external cooler?

Will the transmission fluid be bottlenecked at the rad to raise any concern? The car will not be winter driven.

And can I use PVC coated steal Break lines or will I need Copper lines like it has now? Is there a specific type of metal line I need for the transmission lines?

Thanks

Fiero lines are 5/16 steel. 3800 uses 3/8.
The 5/16 lines will cause no problem.

Joe is correct, using the stock 5/16" sized steel (or Fiero Store stainless) lines with a 4T65-E trans that has 3/8" cooling lines will not hurt anything.

Having said that, I do recommend you disconnect the trans cooler lines from the radiator and run an external cooler. The problem with the stock Fiero radiator is hot coolant from the engine gets dumped right onto the trans cooler inside the radiator which usually just serves to heat up the trans fluid most of the time. According to Dave @ tripleedgeperformance.com, he would like to run the transmission fluid as cool as possible.

If you are going to unhook the radiator and run just an external trans cooler, I recommend you get the biggest trans cooler you can fit in front of the A/C condensor/radiator (I typically use ext trans coolers rated at 26,000 lbs GVW or bigger).

In the past, I have just used rubber trans cooler hose with regular hose clamps to make connections from the trans to the cooler lines and from the cooler lines to the ext cooler. However, this rubber hose can swell and shrink depending on weather conditions and this can allow the hose to work itself loose and even blow off of the lines on the car. I had this happen on my own Fiero. So if you use rubber hose, replace it if it shows signs of drying out or excessive swelling/shrinking and make sure you check the clamps regularly.

In all the swaps I do now, I'm no longer using rubber trans cooler hose. I'm instead using -6 AN fittings and braided AN line everywhere where I used to use rubber hose. You can double flare the steel 5/16" lines on the car to accept 5/16" inverted flare to -6 AN adapters you can get from Summit or Jegs. At the radiator, that end of the trans cooler lines are already double flared so all you need are the adapter fittings. You can buy ext trans coolers that already have AN fittings on them or that are threaded so you can screw on adapters with AN ends. Since I have a TIG welder, I just get the less expensive regular coolers (that just have the regular hose barbs) and weld -6 AN bungs right onto those to save money.

-ryan
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[This message has been edited by Darth Fiero (edited 09-17-2013).]