Flares & Related, 2nd try.
This is the instruction set for the Facom 347 flaring tool illustrating the difference between SAE & DIN bubble flare and the dies / blocks used to make them. They are different, yet generally interchangeable.
There is a copy-similar flaring tool sold by Eastwood, no idea if that flaring tool works. Snap-op/blue-point/Eastman-Imperial bubble flaring tool works OK, but not as precise as the Facom 347. There are others and the low cost-cheap flaring tools produce awful flares along with numerous problems that can cause a lot of grief and potential problems when least expected.
Facom 347 SAE flare die & block set. The split block has an angled recess to form the back side of the SAE tube flare. To make a single flare, OP1 die is used alone, to make the SAE 45 degree double both OP1 and OP2 dies are used.
Facom 347 DIN bubble flare die & block set. The split block has no real angle at the back side of the tube flare this creates a tight shoulder between the tube and flare end. The DIN bubble flare is a single operation with this die.
DIN die graphic illustrated the seat angle and general shape of the DIN bubble flare. The seat angle range is 113 to 117 degrees.
DIN bubble flare as formed using the Facom 347 die and block.
OD of the DIN bubble flared end. Measures 0.281".
SAE bubble flare as formed using the Facom 347 die and block. Note the back side transition of the flared end to the tube being different than the DIN bubble flare.
OD of the SAE bubble flared end measures 0.269".
SAE 45 degree double flare as formed with the OP2 die after using the OP1 die. The center area is the actual seating and sealing area of this type of flare.
Back side view of the SAE 45 degree double internal flare illustrating the transition from tube to flared end.
AN-JIC 37 degree single flare with the tube sleeve behind the flared end. This flared end was made using a Parker aerospace spec flaring tool.
AN-JIC 37 degree sigle flare with sleeve, B-nut and matching fitting. This type of flare seals by compression-strecthing the tube end rather than simple compression as with the bubble and SAE 45 degree internal flare. This difference makes these types of flare ends far more reusable with a more reliable seal over repeated cycles of assembly and dis-assembly.
The OD of the flare relative to the sleeve should be equal it the OD is too large, it will not fit into the B-nut, if too small the flare will not seal properly resulting in leaks and other problems.
3/8"-24 Girling style bubble tube nut. These are common on British cars and cars using Girling brake systems.
End view of the 3/8" Girling style tube nut. There is a small chamfer at the ID to support the tube's transition into the flared end.
3/8"-24, SAE 45 degree internal double flare tube nut.
End view of this SAE tube nut. The chamfer is to support the tube to flare transition.
M10x1.00 DIN tube nut. It is very similar in appearance to the 3/8"-24 GIrling bubble flare tube nut. These can be mixed up with really bad results.
End view of the M10x1.00 DIN tube nut, it is a bit different than the Girling tube nut, yet similar.
M10x1.00, SAE 45 degree internal double flare tube nut. These can be found on Japanese made cars. It is a variant of the SAE version. These are NOT interchanged or used with a bubble flare as the end has a large chamfer causing the bubble to sit too low in the tube nut.
End view of this tube nut. The deep chamfer is different from the other tube nut designs.
M10x1.25 DIN bubble flare long tube nut as used in FIAT brake systems. These are not easily available in the US. They can be ordered in bulk from EU suppliers.
End view of the M10x1.25 tube nut.
Used OEM FIAT, M10x1.25 DIN bubble flare long tube nut. This came from an exxe brake system. The hex is knackared which often happenes due to the nuts getting too happy with the tube, flare seat coupled with various fluids keeps then happy together.
End view of this Fiat tube nut. The end has flared out a bit due to the compression force applied during assembly at Fiat. This is problem varies with the amount of force applied to the joint. If too much force is applied, the flare end, flare seat and tube nut could be damaged causing seeping and leaks. This is why it is not a good idea to "crank down" on tube fittings that do not seal.
Side by side view of the new M10x1.25 tube nut and OEM FIAT tube nut. They are basically identical. Accept no deviations from what is shown if these are to be replaced in a Fiat brake system.
There are numerous warnings and cautions of mixing a 3/8"-24 tube nut with a M10x1.00 tube nut. It is possible to thread the wrong parts together due to their similar thread pitch. Doing so will end in tears and a host of miserable problems for all the parts involved.
Their diameters are different yet similar enough.. The 3/8"-24 tube nut measures 0.370" OD and M10 tube nut measures 0.389" OD.
SAE bubble flare seated into the M10x1.25 tube nut. Not too bad a fit.
DIN bubble flare seated into the M10x1.25 tube nut. This is what the end should look like new OEM.
DIN bubble flare installed and M10x1.25 tube nut torqued to about 12 ft/lb. This is what the bubble flare looks like post install. The flare tube seat used was a OEM FIAT brake master cylinder.
SAE bubble flare installed and M10x1.25 tube nut torqued to about 12 ft/lb. The flare seating surface is quote similar between these two. Primary difference is at the transition between the tube and flared end and how the edges of the bubble flare compresses into the flare seat.
Post install OD of the DIN bubble flare measures 0.282".
Post install OD of the SAE bubble flare measures 0.268".
What they look like post install side by side.
As for real world experience, have used both with good results. No leaks, seepage or problems. This is extremely important as brake system pressures can reach 2,000 psi. If there is a seal failure or blow out of a fitting, the results can be deadly.
All tube flare examples were made in copper-nickle alloy brake tubing. DO NOT USE HARDWARE STORE COPPER TUBING... IT WILL FAIL.
Use only DOT-TUV or similar approved brake tubing as there are very specific industry specifications for brake tubing that MUST be adhered to. Exceptions are if FAA approved annealed 304 seamless stainless steel 0.028" tubing is used or Industrial annealed 316 seamless stainless steel 0.028" tubing is use. These are more difficult to flare, bend and work with, but will meet the required pressures and corrosion resistant at significantly greater cost then copper-nickle brake tubing.
Bernice
Now, back to the last chapter of 5 speed transaxle assembly sooner than later.
