Tips on making your own transmission lines

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Mopar King

Mopar King

Beginner / Need of Help
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I kind of need some help in a DIY transmission line - just a few questions


The car is a Dodge dart - Slant six - automatic transmission 904. I wanted to replace both lines since they were rusted out (broken) and what better way then to just make my own. Reason I want to go this route is because I am going to be putting headers and wouldn't want them to be in the way. I would have them follow the frame of the car so there wouldn't be any interference.


The questions are


  1. is a 5/16 line the right size?
  2. is a bigger line better?
  3. Aluminum line or Steel?
  4. what are the thread sizes of both transmission lines?
  5. Brass or steel inverted flare tube nut?
  6. summit has lots of tube nut sizes/dimensions but im getting lost pretty quickly can some one guide me to the right ones that i need
  7. inverted flare or bubble flare? I think its mostly inverted


Thanks guys for your help again :prayer:
 
I used steel line, and I believe it was 5/16. It was from a roll. We just bent it the way we wanted it and flared the ends. Can't tell you the fitting size, but I run a GM tranny anyway. I ran them to the core s
Support and flared the ends and ran hose to the tranny cooler for ease of disassembly if I ever need to pull the radiator.
 
I used a combination of aluminum hard line, and XRP XR-31 hose, it's a soft braided hose, not stainless braid. 3/8 is about the biggest you can go, no point in going any bigger, the in/out ports on the trans is only 1/8" pipe.

You can use either material you like, but aluminum hard line and of course stainless braided is more expensive than steel. -AN fittings use a 37* single flare, so a special flare tool will be needed.
 
I like steel line. 5/16 is the right size. I like to make a mock up line out of coat hanger wire, then duplicate it with the bender. Makes for a very nice job and you waste less line. What's a "bubble flare"? Do you mean double flare? That's what they are. Double flares. Not hard to do and the tool is cheap at harbor freight.
 
there is such a thing as a bubble flare. Its jus a bubble on the end of the line like on old carb lines where rubber fuel line is clamped on. It is hard to find a flare tool that will make a true bubble flare. You can kind of do it with the double flare tool if you are careful. (the idea is to be able to push on the rubber line without "shaving rubber" and it ending up in your lines. The nice bubble prevents this and also keeps the rubber line from coming off).
On the subject of trans lines, I remember an old mechanic friend of mine back in the eighties that used to use some kind of nylon line with compression fittings. I never questioned this as he was a long time mopar dealer mechanic back in the 70's but I wonder what kind of line it was exactly. I know it was cheap and easy. I think I would vote for the steel 5/16 line.
 
Ok so I will be going with


  1. a 5/16 line :thumblef:
  2. have the option of going alittle bigger but will stick to stock size 5/16 and since the tube nut can't go any bigger than 1/8 :thumrigh:
  3. I ordered and got both but will be using steel for more reliability since it is going to be a daily driver and since the NY streets are not the best:thumrigh:
  4. 1/8 is the pipe size any other sizings that go with the 1/8
  5. guessing whatever is available steel or brass tube nut- just getting confused with sizings as seen on the summit link:dontknow: http://www.summitracing.com/search?keyword=1/8 inverted flare&dds=1
  6. :dontknow:
  7. Inverted double flare is what I am going to be doing - got the tool with a 45* double flare Im guessing this is alright for transmissions? :-k


RustyRatRod: Good tip on the coat hanger wire i'll try that
 
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