C6 Cooler Line Routing

[HarleyJack17]

After rebuilding, installing the C6,  and in process restoring etc. on my 1975 F250, I am not happy with my C6 hard line routing.
As it sits it is a combo of hard line, hose etc. and frankly it is horrible. The hard line is tough to bend, tried the soft stuff but it has its own set of different problems.

I am thinking about running flexible hose so I can neatly route it and tuck it in. Wondering if anyone has any experience with it, fittings, recommendations, how you did it.  There are pros and cons to both, so just seeing what is out there and real world experiences.

[Falcon67]

Don't know right off if the C6 uses 1/4 NPS thread fittings with an o-ring or NPT style.  Summit sells adapters to go from some NPS threads to -6 AN and of course NPS threads to -6.  Either would allow you to run common 6 AN (5/16ish) braided or push lock pressure lines where you needed. I used to make 1/8 NPS x -6 fitting for use in C4s to run braided lines.  I've had braided -6 on the race car trans for many years.  Way nicer than the hard line and fittings IMHO. 

[cleandan]

I believe the C6 uses 5/16" inverted flare connections on the transmission, and on some of the hard line mounting coolers....otherwise it will be some type of barbed hose end on the cooler in most cases.

I have found a good bender (or three), and some experience, are what gives the best results.
It also makes a difference which type of hard line you are using.

Much of the stuff available at local auto parts stores is either coated with something, or the line is quite a bit more rigid and brittle than from years ago.
These factors make bending more difficult.

Grease...regular bearing grease, used where the bends and the bender will touch, gives much better results too.
Making hard bends (more than 70*) often works better when done in tiny stages with careful observation and adjustments as needed.

Sometimes you can make the whole bend in one shot, but most of the time you can not, especially if you are going 90* or more...the hose just kinks, crushes, or bends weird.

My personal favorite is to source a good cooler with hard line fittings, or the ability to install hard line fittings.
If it came equipped with barbed hose ends I don't like it...I've used them, but I don't like them.

I bend and run the lines in a smart area.
Then cut to fit and form the proper ends with a good flaring tool (hard to find these days for less than $350)

Take you time, bend carefully, and soon you will have great had lines that will last basically forever.

You can run the braided lines. Just keep in mind they may deteriorate over time.
Because of the possibility of deteriorated rubber getting in the trans I have not run the braided lines.
Teflon, or some other poly coated lines, would probably alleviate this issue greatly...still, the flexible lines do have a shorter lifespan than the hard lines.

For the flexible lines to work all you really need is the ability to install the desired fittings to mount the hose.

I suspect you have a local commercial fluid transfer supplier in your area. Around here there are two big names (hose and conveyor) (Pirtek)

Places like this will often build you a hose to your spec...except for brake lines...lots of rules concerning brake lines. But you should be able to get what you need to install a nice set of lines.

[manofmerc]

Consider buying something from a restoration parts supplier .I put new cooler lines on my 73 f 250 a couple of years ago .The new ones were much nicer than my old ones.But whenever they were shipped out they bent my new lines and put them in a shipping tube I got them straightened out but it was a hassle .Maybe Dennis Carpenter does better .I bought my cooler lines from Summit .And like others said you can get a nicer connection made for your cooler by going to a hyd. hose store I did the same thing .Doug

[RustyCrankshaft]

There are some exceptions I'm sure, but I've found if it's an older C6 with screw in modulator it'll have 1/4" NPT in the case and later cases with push in modulators usually have 1/8" NPT in the case. In each case some sort of a-dapter fitting is used, usually an inverted 45* flare.

On my 73 Camper Special I used JIC fittings in the case and used stainless PTFE hydrualic/truck hose for the cooler lines, all 3/8", bypassed the rad cooler and run a big Hayden cooler out front of the AC condenser. With a temp sender in pressure test port it's rare I see more than 150*, verified within 5*F in the pan with a laser. I ran the hoses up the inside of the frame, used the bracket for the stock aux cooler to p-clamp them to and then under the core support and up behind the grill trying to keep them as far away from the headers and everything else. Not the prettiest install, but this isn't a show truck, I actually use it almost every day for something.

[Falcon67]

Concur that the fittings receiver side is 5/16 inverted flair.  5/16 parts store brake line ends fit the fittings on both C4 and C6.  I personally prefer the AN lines over any hard lines - the fittings use way less torque to seal, no rounding off the flare fittings and you can run lines any way necessary to clear items.  Just have to be sure what thread in is the case.  You can force an NPT fitting into an NPS threaded port but you take the chance on cracking the case by doing so.  Line pressure to the cooler is only in the 20~30 lb range or so, if that.  I've tested hand tighten o-ring to case C4 -6 AN fittings to over 80 lbs air pressure and they held.  1/8 turn with a wrench gets 100 PSI. 

[HarleyJack17]

On my 73 Camper Special I used JIC fittings in the case and used stainless PTFE hydrualic/truck hose for the cooler lines, all 3/8", bypassed the rad cooler and run a big Hayden cooler out front of the AC condenser. With a temp sender in pressure test port

I like this idea. I was a bit rushed trying to debug the engine etc. so I did not get to my plan on installing a pan bung for a temp sensor. Like you this is going to be driver, not a show queen, but by no means a throw together job. Currently sanding and filling in prep for paint.  Temp monitoring would definitely be nice.
 
Just for clarity the truck 1975 F250 4x4 with the short tail shaft, divorced t-case. I really want to say the fitting are are 1/4 NPS...not NPT but hard to tell, for me, by looking at the threads. The modulator is push in.

I've had braided -6 on the race car trans for many years.  Way nicer than the hard line and fittings IMHO

I will verify the fittings and take the route of flexible hose. It would make the install more clean and clear any dangerous items.  Prefab hard lines were not really an option as they normally arrive bent, and I have some aftermarket parts that may would change up stock routing.

Thanks for the info guys.

[RustyCrankshaft]

I have heard some C6's had NPS threads, I just have never run across one yet. The thread in modulator case I have was definitely NPT and most of the newer cases still had the adapters for the hardline and none of these had any seal on them and were all tapered thread. I'm sure the numbers are lost to posterity but it would be cool if there were records of the case revisions.

The original C6 in this truck I put the temp sender in the pan along with a drain plug. It had an odd lube issue that destroyed the sprag and the shop was full and I paid a "reputable" shop to rebuild it and that went sideways and I bought a no core TCI from Summit with a POS, but for now it'll work until I get around to the rebuilding my professional rebuilt original and that's why I currently have the sender in the test port.

I agree, JIC is just a much nicer fitting that leaks less and is just more reliable. And since I deal with equipment and big trucks and boats, so I have plenty of JIC stuff around.

[Falcon67]

>I'm sure the numbers are lost to posterity but it would be cool if there were records of the case revisions.

Wish same.  In all the years I've messed with C4s and made/shipped adapter fittings all over the planet I never found any references to the case thread or installed fitting data.  Had people return fittings because the C4 case they had used 1/4 NPS or NPT vs the nearly common 1/8 NPS o-ring.  And all the time spent poking through piles of transmission in wrecking yards I never turned up one to test with.  Early, mid 70s, "C5" units etc.  Be super nice to find some application data somewhere.