Bulk brake line replacement - fittings and flaring?

[LonghouseIndian]

Sent: 11/13/2006 2:32 PM

  I am replacing all of the brake lines and hoses on my '73 Indian and decided to use a roll of soft steel tubing rather than the sections with fittings already on them. The package says it is brake line but it looks nothing like the other stuff. I use the same flaring tool that I used on the soft copper plumbing. Is all of this safe and do I need special fittings (is brass compatible with steel)?

[brians1969]

Sent: 11/13/2006 2:45 PM

As I understand it, brake line has to be double flared.   I will be replacing all my tubing too, so I will be watching this thread for any comments or tips.

Brian

[denisondc]

Sent: 11/13/2006 5:38 PM

Ever since I first worked with brake lines on motor vehicles I understood they had to be made of Bundy tubing. I know it comes in rolls, as well as standard lengths. I expect to try a roll of the tubing when I redo the lines on my winnie, along with using some of the standard lengths. My intention is to have as few mid-line couplings as I can, but still be able to install the new lines on/around the existing stuff on the frame. And to have a safe system......

I got some parts from a wrecked RV chassis that had recent replacement brake lines. They must have been made from a roll, because they werent nice and straight. They wandered and curved; touching the frame in several places, and were not firmly clamped. It occurred to me that any place where the brake line would rub against the frame was a bad thing. The reason that RV was wrecked was because it had smashed into the back of a piece of heavy construction equipment. I couldnt tell whether the crash was due to driver inattention or brake failure.

I recall many years ago needing to make the double flares that are required. It took a fair amount of practise, a quality flaring tool, and some luck to get the tubing flared properly (i.e. without cracks). 

[Cooneytoones]

Sent: 11/13/2006 6:09 PM

Yes Dave, I believe you are correct bundy tubing must be used due to the corrosiveness of brake fluid....about the most corrosive fluid in a vehicle....the only other fluid that is as corrosive is the solfuric acid in the battery....And it won't take long to etch away a brake line if it is touching the frame and not stabilized.

Rolled tubing is the cheaper way to go to get a longer run...but it is not very easy to flair...as you said it cracks very easily. I would recomend using a good "Ridget" (brand name) flairing tool...they are a little more costly, but will make it easier, the holding clamp is much better than most flairing tools,   and that is the key to getting a good flair, no movement of the tubing keeping the tubing from slipping through the clamp, and keeping the flair even  or square for 360 degrees, and doing it in one shot....that is the best way to crack the tubing by haveing to tighten down on the flair more than one time, it is not real hard, but takes some practice. Bundy tubing flairs much harder than copper, due to the fact that it is steel, and can be a harder steel than most cheap pot metal flairing tools.

Yes ...brass fittings are compatable with steel...

Keep it safe...
Timmy

[LonghouseIndian]

Sent: 11/14/2006 1:22 PM

  Thanks. Glad I've only done two because I have no idea what a double flare is. I think I'll use the pre-measured lengths for the rest. Just wanted to avoid using unions to go to the back.

[Slantsixness]

Sent: 11/14/2006 2:34 PM

Another Brake Rant !!

Buy pre-made brake lines. they come in many lengths (including ones long enough to span all the way to the rear in one shot in a 21 foot motorhome (which is 16ft), they MUST be double flared, and if you want to make your own, there's a talent along with a $125 tool to make double flares. I started to do this myself, but quickly found out that the correct diameter brake lines are readily available, and considering the cost of the Double flare tool (which takes some effort to make perfect flares every time by the way)....

anyway it was A LOT cheaper to buy the various size lines and connection adaptors and unions, and bend them myself. I redid ALL of my brake lines, with a professional tubing bender that I bought at (of all places) Auto Zone for less than $20. 
Using the brass or "Japanese stainless" unions is perfectly acceptable in any hydraulic application (Japanese stainless is a stainless steel that almost looks like it could be brass but has a rainbow or pearlescent effect to the brass tint) Aluminum unions are not good, they are fragile and can crack or leak in automotive applications and are very easy to cross thread.

Use DOT 4 brake fluid, and replace it all, do not mix various types of brake fluid. Brake fluid also has a finite shelf life. That old can of DOT 3 that's been sitting there for 10 years is useless, and has probably introduced the coating from the can or bottle into the brake fuid. Old brake fluid can cause all sorts of premature corrosion problems. Use new sealed containers. And remember, the fluid in your brake lines will go bad too, in around 5 years and begin to eat away at the rubber parts it comes in contact with (like the master cylinder, piston cups and seals, caliper seals... and it will corrode the wheel pistons over time also. Brake fluid is nasty stuff, but it's better than cable brakes!
I've never seen a benefit to Synthetic Brake fluid either, just a waste of money... maybe it's ok in some Corvette, or Ferrari.. but hydraulic fluid overheating is not an issue in a motorhome, so don't waste your money.

   NEVER NEVER NEVER use compression fittings or single flare couplings in hydraulic brake applications. If you do, you're taking your life in your own hands, and let us know so we can stay far, far away from your rig on the highway! They will fail, and when they do, you don't stop!

Tom   

[denisondc]

Sent: 11/14/2006 3:10 PM

I would agree with almost all that Tom said. Making the double flares may be as much an art as it is a science. I didnt think to ask if they could order me the pre-made lines in lengths longer than 60", but I will now.

There have been several types of brake flares in use, but I think only the double "reverse" flare kind has been used in the U.S. since the end of WW-II. I once had a British car whose brake lines had "bell" flares. The ends of the brake lines looked like a little round ball.
I would say the useful life of brake fluid is only 2 years, unless you live in a very dry climate. By this time it will have absorbed enough water from the air to be rusting the inside of your wheel cylinders, master cylinders, or calipers (all made of iron or mild steel). The Bundy tubing doesnt seem to rust from the inside, as it is coated with a tin/lead alloy. So is the outside, but every brake line failure I have ever had was advanced rust from the outside in. And this rusting doesnt happen fast - so have a close look at all of your old brake lines now and then.

I also must defend cable brakes. My 32 Chevy stops allright - though I dont drive it at 70 mph on interstate highways either. There are lots of places where you need to lube its cable pivots/equalizers/bellcranks too; 49 of them.

I have a 3.5 liter Bentley with cable brakes that are superb. They are mechanically power assisted, and have an antiskid feature that still works: Anytime you hit the brakes hard enough to lock up the rear wheels, the front wheels will not-quite lock up, and you stop in a straight line. And it works equally well on dry pavement, gravel, and even wet grass!
Have a look at this URL:
www.dimebank.com/BrakePlumbing.html.

[Slantsixness]

Sent: 11/15/2006 6:54 PM

Over 60" premade steel hydraulic bake line.
Lane Auto Parts, Fredericksburg VA. I don't know if this is recurring stock, or  NOS stuff, but it saved me a couple of unions! He even had some stuff that was way too long, for City school busses, he said. This was a year and a half ago, but If you've ever been there, not much has changed at Lane since 1960 something! He did have all of Kev's wheel lugs (5 lug budd) in stock, and right cheap, too.

[Lefty]

Sent: 11/17/2006 3:30 PM

A quick note in addition to Tom's comments. I wanted to make sure everyone realized what he meant by "Compression" fittings, and why they shouldn't be used.

Brass compression fittings, such as a "union" which uses a sleeve compressed over the line, is only rated for somewhere around 150 psi or so...  This is not because of the Brass not being strong , note Brass couplings are regularly used in disc brake settings, rather, the compression sleeve itself relies solely on friction grip to hold the line together, and at high pressure the lines literally slide out of the fittings. And that makes for a very scary stop!!

Compression fittings are perfectly fine for joining water lines, or fuel lines together. But drum brakes operate at pressures of up to 300 psi. and disc brakes operate at pressures over 1000 psi. Enough to blow a compression fitting all to pieces. Be Safe!! There are special "extreme pressure" compression fittings available through auto parts dealers (NAPA,O'Reilly's,etc...) They are black in appearance, and are rated for up to 3,000 psi. if you must have a union to add on additional line.

Lefty