Tubing and Tools
Authored by Wes Vann, last revised on September28, 1997
PLEASE NOTE; Any of the fluid lines in your car should be checkedfor leaks prior to doing that high speed run down the road!! A gas leakcould cause a fire, a trans line leak could trash your trans, and a brakeleak could, well, you know what would happen. Check the lines after theyhave been under pressure.
ALSO NOTE; When shopping for hose line, be sure that the hoseis designed for the type fluid and pressure that it will see!
Hard lines; These are the steel tube lines.
Most of the original hard lines and the stuff that you buy at your localcar parts store is just mild steel. If you look inside the standard tube,you will notice that there is a seam where the tube has been put together.
I will sometimes refer to "bundiflex" and this is thetubing that you can get at your auto parts store with the ends alreadyflared and the fittings in place (bundiflex is just a generic name). Youcan buy this stuff in differing lengths and is the cheap and easy way toget a job done. The stuff bends real easy and the smaller sizes can evenbe bend by hand. No show quality here, but it may get you back on the roada few days faster!
There is nothing wrong with buying a bundiflex line and cutting it shortto fit the exact requirements for what you need. By doing this, you onlyhave to flare one end, and you also already have the fittings.
"Stainless Steel" hardlines are made of (you guessed it),stainless steel. This type tubing can look just fantastic when buffed outwith a brillo pad. The stuff is extremely strong and requires that youuse the high dollar tubing benders and quality flare tools. It's normallyreferred to as "seamless" due to there being hardly any seamwithin the body. This stuff looks good, but is real costly. If you aremaking the lines, I'd recommend that you experiment with a lot of the cheapline before spending the money for the stainless. I've thrown away a lotof stainless line due to it not being "just right"!
Hose lines (or flexible lines); These arethe rubber tube lines.
Vacuum line is just a rubber tube and there isn't any form of wovencloth body within the tube. This type line is not intended to be underpressure and only a small amount of vacuum.
Fuel line has a woven cloth (or rayon) material within the body of thehose to prevent it from expanding under pressure. The type of rubber issuch that the gasoline that you are using will not eat at it. I'm underthe impression that if you run high concentrations of nitro-methane ina standard fuel line, it will destroy the line. It's for this reason thatif you don't know, ask! If the guy behind the counter doesn't know,go somewhere else!
Standard brake lines have a woven material within the body of the hoseto limit the expansion when you hit your brakes. There is expansion, andthat is one of the reasons that steel braided hose is used for race cars.
The "steel braided" hose that most people think about hasa woven stainless steel outer cover. There is also "steel braided"hose where the braiding is covered with an outer cover of rubber. As withall other types of hosing, there are different types depending on the typeof fuel used. It's possible for a steel braided hose to look great onthe outside, and yet the inside is being eaten out by the fluids it carries.
Tapered "pipe" fitting; When "pipe"is put together, the threads on both the male and female ends have a taperto them. It's this taper that forms the seal and some form of sealant isnormally used.
An example of where you would find a pipe fitting on your Chevelle wouldbe at the oil pressure sending unit at the end of the block. On my car,I am running Autometer electrical gauges and I also wanted to retain theidiot light. To do this, I had to remove the stock idiot sending unit,add a short pipe extension, and then a "T" fitting. All of thesewere stock "Edelman" pipe fittings.
Hard line "single flare";
This type flare should only be used on "stainless" hardline.Due to the strength of the stainless line, a double flare isn't requiredand would be extremely hard to do. Note that the inside of the tubing isthe sealing surface. Stainless tubing is referred to as "seamless",in that there is very little seam on the inside surface. Keep in mind thephrase "very little seam"! Due to the small amount of seam, stainlesstubing can be a problem to get to seat correct. Farther down, I'll talkabout brass washers that can solve this problem.
Hardline "double flare";
This is what you will see on most production hardline tubing. The tubingis first flared out, and then back down on itself. Note that the sealingsurface is the outside of the tubing. The reason for doing a double flareis to prevent the tubing from splitting at its seam and also to have thesmooth surface of the outside of the tubing become the sealing surface.
You will see this type of seal on some power steering lines and on airconditioner lines. This type of flare or crimp can't be done without costly(major money!!) tools. The tubing is crimped to create a seat for the o-ring.If you find that you have to modify this type of fitting, I recommend thatyou find an existing section and modify the other end.
"AN" fittings; The cool and costlyfittings used on stainless braided line. The term "AN" goes backa long time and stands for Army/Navy. It has to be noted that the angleof the seal on AN fittings is not the same as the standard flare.
(as a personal note, I am not going to talk about fake AN fittings asI feel that it's just a cheap show item that kids use. Sorry if this offendsanybody)
There are three basic manufactures of AN fittings, Aeroquip, Earls,and Russells (although I question if Russells really makes them).
The inside of the fitting end had a serrated edge that grabs onto themetal braiding of the hose to prevent it from pulling loose. Although thefittings are not difficult to install, you have to have a cutter that cancleanly cut the metal braid. The fitting can be removed and used over (butyou trash the end of the hose).
There are various types of AN fittings available. 45 degree, 90 degree,Bango fittings, etc.
The hose (once constructed and installed) can be disconnected from whatit's attached to (the carb?) with no damage to the hose or fittings.
It should be noted that standard AN fittings have no provision for rotationof the hose once installed. For that reason, it's recommended that at leastone end has a "swivel seal" fitting. This is the term coinedby Earls and is for a fitting that can rotate after being hooked up.
There are tons of different types of adapters for AN lines however,sometimes you have to dig to find them. (I've done my fair share of digging!!)Chances are that anything that you want to do has already been done andthere is the correct adapter sitting in a box on a shelf!
TUBING CUTTERS AND BENDERS;
This photo shows a tubing cutter and a "high dollar" tubingbender.
A tubing cutter has a cutting bit that cuts the tube by rolling aroundthe tube. The good part of this is that the cut is "square".The bad part is that it rolls in the end slightly. Most cutting tools alsohave a cutter for cleaning the inside edge.
The "high dollar" bender is the type that you will have tohave in order to bend stainless tubing. They are costly (the one showncost me about 50 bucks!) and only fit one size tubing. I've ended up buyinga 3/16" for brake lines, and a 3/8" for trans and fuel lines.
This is a photo of a "low dollar" tubing bender. With this,you can bend a variety of different size "mild steel" tubes.Don't even think about using this for stainless steel tube! You will kinkthe tubing and hurt your hand (BTDT).
This is the tool required to flare hard lines.
The tool is easy to use for most soft steel hard lines, and slightlyharder for stainless. A quality flare tool will have serrated edges wherethe tool clamps the tube (to prevent it from sliding while flaring).
The tubing is clamped between the two side plates in the correct holefor that size tube. Then the clamp is installed and the cone wedge screweddown.
When doing a double flare, the little round adapter is first crimpeddown on the end of the tubing. Then it's removed and the flare cone screweddown again, making the double flare.
I promise that I'll get a photo here!
Not a "box" wrench, not an "open end" wrench, a"flare-nut" wrench is one of those wrenches that go almost fullcircle around the nut. The opening is only large enough that it can befit over the tubing.
If you are doing brake lines, you have to usea flare nut wrench or you risk rounding off the nut! They can begotten at Sears, so there is no reason for not having one (or several).Buy them a week before starting the job, just so that you know you havethem and are not tempted to do the work without them!
Due to their being several postings by people who have leaks at fittingswhen installing stainless steel hard lines, I'm adding this new section.It's totally a "been there, done that" subject. I did most ofthe hard lines on my 64 wagon in stainless. This includes the bending andflaring of the fittings. I ended up with a fair amount of leaks that werewell beyond what I would contribute to poor workmanship (heck, I did it).After swallowing my pride, I talked to the owner of the hose supply shopthat I buy stuff from. It ends up that it's not that uncommon, even withthe pros and their major high dollar tools!
The problem is that stainless steel tubing is NOT seamless. Don'tbelieve me? Just look inside and you will see the seam! It's small, butit's there.
When flaring stainless tubing, you only do a "single" flare.(as far as I know, it's not possible to do a double flare with stainless)As a result, what was the inside of the tubing becomes the sealing surfaceand that little seam can cause problems.
Here is the trick; You can get soft brass, cone shaped washers. Thesewill conform to the non-perfect shape on the end of the stainless tubingflare. They go between the item the hose is connecting to and the hose.They come in several sizes however it always seemed that I ended up havingto sand down the diameter in order to fit correctly. Maybe somebody hasa larger selection of sizes. I wouldn't recommend that you reuse the washersa second time due to their having already deformed.
I order to locate the washers, I recommend that you find the shop intown that rebuilds hoses for things like fork lifts. If you live in a farmtown, try places that service tractors.
The simple fact is that I don't know who the manufacturer is or if theywill send you just a couple. A minimum order of 500 would sure last a lifetime! If anybody knows of a supplier that will dealin small quanities, please let me know and I'll post them as a source!