Brake Line Flaring - Procedure + Questions

[RWBeringer4x4]

Hey everyone,

I made my first attempt at some brake line flares yesterday. I also took some pictures outlining the process. I'll put them here in case anyone else is looking to try this, then ask some questions pertaining to flares and flare nuts - as usual, my first attempt left me with more questions than answers!

I had never done this before, and didn't see this procedure outlined, specifically, anywhere. So, while it may be "basic knowledge" to most, it certainly wasn't to me, so I thought I'd share!

First off, the procedure:

Tools:

• Brake Line - 3/16in (I used Nickel-Copper-Iron Alloy, called Cunifer and NiCopp in some places)
  Note: Stainless Steel, Steel, or any line approved for brakes will work as well.
• Tubing Cutter: I have this one, but any will do.
  http://www.otctools.com/products/heavy-duty-tubing-cutter
• Double-Flaring tool. I have this one (because it was cheap). Eastwood sells a much better hydraulic one.
  http://www.otctools.com/products/double-flaring-tool-set-cutter
• A metal file
• Flare nuts - I bought two #14 Nut Packs from Federal Hill. 10mmx23mmx1.0 Fine Thread w/ non-threaded lead
  http://store.fedhillusa.com/14nutpack.aspx
• Brake Fluid (for lubrication)

Note that in this case, I was just practicing flares - you'll notice there is little (if any) brake line attached in most cases. That's because I was cutting off the flares and trying again. I'm hoping to get good at this before trying this on my actual lines.

PROCEDURE:

VERY IMPORTANT: If you are flaring your ACTUAL brake lines, ALWAYS be certain to put your flare nuts on BEFORE you flare the line. Otherwise, you get to do it twice!

Use the tubing cutter to cut as flat a cut through your brake line as evenly possible. You will need to de-burr and chamfer the end of the line. But starting with a straight cut is essential.

I apologize in advance for blurry pictures - close ups and iphone do not work well together...

STEP 1.

I found mounting the flaring tool upside down, with a very small section of tube exposed, was a good way to provide a level surface to file the end of your brake line down flat against. Just leave a small section of tubing exposed, then file until you make contact with the flaring tool - this will get the line nice a square.

STEP 2:

Use a reamer (usually attached to your tubing cutter) or a metal file to de-burr the inside diameter of the brake line.

STEP 3:

If you were using the back-side of the tool to flatten and prep your line, flip the tool over in the vice. Load the tubing back through, with just enough material exposed to be as tall as the first shoulder on your 3/16 adapter (part of the tool kit).

CLAMP BOTH NUTS DOWN FIRMLY. Once you start flaring, the tubing can't be allowed to slip. This is key to an even, centered, flare.

 

[RWBeringer4x4]

STEP 4:

Chamfer the outer edge of the tubing, slightly. Then, lubricate the end of the tube, and the adapter, with a little bit of brake fluid.

STEP 5:

Insert the adapter onto the tube, then attach the clamp apparatus, and twist until the upper shoulder on the adapter is flush with the top of the tool.

This creates the outer portion of the double flare.

 

[RWBeringer4x4]

STEP 6:

With the adapter REMOVED, re-align the clamp. Twist down the cone on the clamp into the inner diameter of your tube. I lubed the clamp-cone with brake fluid here as well.

This results in your final, double flare.

 

[RWBeringer4x4]

Now, my questions:

The Flare Nuts: I bought 24 flare nuts from Federal Hill that matched the specifications for the stock nuts on my land cruiser. That said, there are some definite differences. Particularly, in how the flare seats in the Toyota nut, vs. the Fed Hill one:

Aside from being considerably longer, the flare tends to sit "on top" of the nut on the Fed Hill line (in the back) where it sits "down inside" the Toyota nut, with just the top of the flare protruding.

It appears that the inner edge of the toyota nuts are chamfered, to allow the flare to seat more deeply in the line. The Fed Hill nuts do not.
Is this going to be a problem, once installed on the truck? Or is this just a slightly different design that should not cause issues?

 

[Weber Sarge]

You're overcomplicating it a bit , no offense . First , using a tubing cutter should result in a decently square cut , or at least square enough to work with . Second , set the line height to the step on your forming die and lock the line down in the frame , it is really important to get that line clamped as tight as you can - it must not slip . With the die in place form the first step of the flare head , remove die and use the press screw to finish the flare - that's all you need to do . Lubricating it does help , good tip for those that are starting out .

In the last pic , that final flare is not seated all the way and the line will leak over time . The final result should have a wall on the opening of the flare equal to the wall thickness of the tubing itself so it can form and seat onto the male fitting when assembled . Look at a factory formed double flare - you'll see what I'm talking about .

Good pick of flaring tool , I've had one from Matco for years and it's never let me down .

Sarge

 

[Weber Sarge]

We must have posted at the same time , lol . The difference in chamfer shouldn't matter , the line is intended to form to the male fitting . You'll know if the fitting and line flare isn't right - you won't be able to start the line more than 1-2 threads by hand and it's not enough to pull down and form the line seating face .

Overall looks fine to me , how well does it seat against a wheel cylinder fitting , ect ?
Sarge

 

[RWBeringer4x4]

Question 2: Flare Quality

I ran into a couple situations with my practice flares - and I'm not entirely clear on how any of them will affect the flare's ability to seal.

1. Inner chamfer - how much is "too much?" Unlike the adapter step - you can keep cranking the clamp down pretty much indefinitely, and really mushroom the flare (some good example of that in the pictures above). How do you know when to STOP tightening the clamp when pressing in the inner angle.

2. Flare centering: I know it is important, but in some cases, there was an obvious, if slight, off-centered-ness to my test flares. Is this the nature of hand making your flares, or will this cause problems once installed?

 

[RWBeringer4x4]

"Bumps" on the outside of the flare due to the gab in the flaring tool:

Not sure how apparent they are in these pictures, but in some cases, I ended up with a "lump" on the flare, I believe from where the gap in the tool is formed when clamping around the tubing. Is this caused due to the line slipping, or is this the nature of the tool?

 

[Weber Sarge]

Centering is sort of a learned process - allow the A-frame press tool to sort of "float" it's tip against the line before applying pressure to lock it down against the line clamping frame , this should self-center it . I've used this tool underneath a vehicle , that takes a bit of practice but works perfect and the lines seat with no leaks .

Yes , you can overtighten the the A-frame and thin out the flare walls too far - this will result in the formed end of the line breaking off . Just need to teach yourself and your hands the correct torque to apply , that Nico alloy line is softer than most types so be careful , may have to remove the tool and inspect your progress at first until you learn the limit .

Sarge

 

[Weber Sarge]

The bumps should not affect the line , they are from the clamp frame and normal with this type of tool .
Sarge

 

[RWBeringer4x4]

Sarge, as usual, thank you for your (downright immediate) responses.

You're overcomplicating it a bit , no offense . First , using a tubing cutter should result in a decently square cut , or at least square enough to work with .

Good pick of flaring tool , I've had one from Matco for years and it's never let me down .

Sarge

I am no doubt overcomplicating it - it's what I do, but this is all new to me so I'm erring on the side of caution. Glad to hear I'm on the right track though. The tubing cutter is providing a (mostly) square cut, but I end up with it being "raised" slightly toward the center of the tube, so I file it flat and then ream it.

The difference in chamfer shouldn't matter , the line is intended to form to the male fitting . You'll know if the fitting and line flare isn't right - you won't be able to start the line more than 1-2 threads by hand and it's not enough to pull down and form the line seating face .

Overall looks fine to me , how well does it seat against a wheel cylinder fitting , ect ?
Sarge

I haven't tried to seat them yet - I wanted to make sure that nothing was catastrophically wrong first! I have an old clutch cylinder and a proportioning valve I can try to seat them in - maybe I'll give it a shot.

Yes , you can overtighten the the A-frame and thin out the flare walls too far - this will result in the formed end of the line breaking off . Just need to teach yourself and your hands the correct torque to apply , that Nico alloy line is softer than most types so be careful , may have to remove the tool and inspect your progress at first until you learn the limit .

Sarge

This is what I ended up doing - stopping and checking occasionally on some. Over-thinning is obviously bad, but I'm assuming you can also not turn the screw enough, and wind up with the walls too thick. I guess that part will be "trial and error"

The bumps should not affect the line , they are from the clamp frame and normal with this type of tool .
Sarge

Good to know - just seems like the interfere with the line seating against the nut. If you look at the last picture, the steel line is a "Toyota" flare - looks a lot different than mine - hopefully they'll both work...

Lastly: Here are several of mine, lined up - how do they look? They seem to seat against the nuts OK - but they all seat higher in these new Fed Hill nuts than they did in the chamfered Toyota one.

 

[Weber Sarge]

Yes , the flare seating height is related directly to your nut choice , er ....

Anyway , a different brand of nut may help - I usually just use the good zinc coated ones from any Parts Store (other than VatoZone) . The taper in most is identical to the oem nuts , the ones you have are different for some reason although they'll probably work just fine .

Also , I know the cutting tool leaves the end of the line a bit convex or tapered at the end , this is not an issue as the extra material will be used in forming the flare and help prevent it being overly thinned in the process . So , don't file it off - that was my point earlier .

Sarge

 

[RWBeringer4x4]

Yes , the flare seating height is related directly to your nut choice , er ....

Anyway , a different brand of nut may help - I usually just use the good zinc coated ones from any Parts Store (other than VatoZone) . The taper in most is identical to the oem nuts , the ones you have are different for some reason although they'll probably work just fine .

Also , I know the cutting tool leaves the end of the line a bit convex or tapered at the end , this is not an issue as the extra material will be used in forming the flare and help prevent it being overly thinned in the process . So , don't file it off - that was my point earlier .

Sarge

Thanks Sarge -

These nuts from FedHill say they can be used with inverted flares or ISO/Bubble flares, so I might keep them, run them, and see how they work out...

My final question: refer to the photos back up in Post #7 - See how the edges of the flare are slightly asymetrical. From the top, they look pretty centered, but from the side, one shoulder is clearly a little wider than the other. Would this cause problems or am I splitting hairs?

 

[B y r o n]

One of the reasons your seeing differences in the flares you are making and the ones on the car is because they are different. The FJ40 comes with ISO bubble flares and you are making double flares. They may provide you the necessary information to clear it up. There are also videos on YouTube showing how to make bubble flare with double flare tool.

 

[RWBeringer4x4]

This is the first I've heard that - everywhere on this forum I've read indicates 45-degree inverted double flares. My steel brake line I was using for comparison came off an FJ62, not a 40 but that may not matter...

In short, I'm not sure this is true...I'm pretty sure the FJ40 uses 45 degree, inverted double flares.

 

[RWBeringer4x4]

I realized there might be some confusion above: The "bumps" in the tubing I'm referring to are not from the clamp teeth, but rather, the gap in the clamp:

Maybe this is what Sarge was referring to as well, but it seems like this would prevent the shoulder from sealing properly against the nut?

 

[vtgbeemer]

I read the description of the nuts as being for either bubble or double flare but a double flare does not look right at all. Have you tried screwing a test piece into a female fitting and tightening, then taking apart and examining? When a flare is right, the tube should slip in smoothly against the seat and the nut slide easily on the tubing , into the fitting and thread (by hand) until you cannot wiggle the tube in and out. The final tightening should be short and sweet, sealing the joint.

 

[RWBeringer4x4]

I read the description of the nuts as being for either bubble or double flare but a double flare does not look right at all. Have you tried screwing a test piece into a female fitting and tightening, then taking apart and examining? When a flare is right, the tube should slip in smoothly against the seat and the nut slide easily on the tubing , into the fitting and thread (by hand) until you cannot wiggle the tube in and out. The final tightening should be short and sweet, sealing the joint.

I have not tried screwing it into anything yet...next time I'm at the shop, I'll try running some of the flare (including my stock toyota flare/nut) into my old clutch master cylinder I have laying around. I have a Wilwood proportioning valve as well, but my guess is it won't want the long, unthreaded neck portion that the Toyota female fittings require.

 

[RWBeringer4x4]

I read the description of the nuts as being for either bubble or double flare but a double flare does not look right at all. Have you tried screwing a test piece into a female fitting and tightening, then taking apart and examining? When a flare is right, the tube should slip in smoothly against the seat and the nut slide easily on the tubing , into the fitting and thread (by hand) until you cannot wiggle the tube in and out. The final tightening should be short and sweet, sealing the joint.

Ok, I messed around with these flares some more tonight. @vtgbeemer & @Weber Sarge, I'm hoping you guys might have some more input.

First - the test fitting: a very old, crusty Clutch Master Cylinder I had laying around.

It also turns out I'm dealing with 3 separate flare nuts. One from FedHill (the shiny new one) and two that came off the brake caliper hard-line of an FJ62. I did notice that one FJ62 nut has a non-threaded lead, like the FedHill ones do, while the other one is threaded all the way to the end.

Deeze nuts:

And, as mentioned before, the Toyota nuts have a beveled/chamfered inner diameter that allows the flare to sit more deeply in the nut:

 

[RWBeringer4x4]

So I first installed all the nuts (without flares installed) to ensure they threaded nicely/properly. They all did. Obviously, because the FedHill nut is considerably longer, you wind up with some exposed threads, but size and pitch were both good, it ran right in:

Next, I installed some sections of flared line. "Gray" steel line is the old Toyota brake line I butchered, and the bronze looking line are my practice flares in Ni-Copp/Cunifer.

Toyota Flare and Flare Nut:

My Flare/FedHill Flare nut:

Both appear to function the same - the unthreaded lead nuts both "lock" the flare in place when tightened. Neither line could move in/out or rotate once tightened. Neither bolt had an issue being twisted in. Both could be run in by hand without any real effort or interference. In fact, the only place where I noticed a difference, was with the completely threaded Toyota nut. In this case, the line was able to spin freely after tightening (probably just the wrong nut for the application). In short - outside of performing a leak test to see if these FedHill bolts actually SEAL, it seems like they will function the same - even though they are fundamentally different. Does anyone see any reason to think otherwise?

Lastly, after being driven home, the flare developed a new "lip" around the top. Not sure if you can make it out in this picture:

I'm assuming this is "normal" and part of how the flare creates a seal when it seats? Is the inside surface, or the outside surface of the flare the "sealing" surface?