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Preface:
If you're doing a BMC conversion for Z32 brakes and you don't have an S13/14 junk cylinder to pillage for the special pressed in fitting (which is a proprietary Nissan part which does not show up in their parts chain), there are other ways to go about putting the master cylinder on your car.
The method I am doing this weekend- and have just tested for sealing on my new Tokico 1" BM50 BMC is as follows.
Before you start buying parts listed in this guide (while they are cheap)- remove your middle port plug using a metric 5.5 Allen Key. You can hammer it in until it sits enough to twist the plug out. A good Allen key set will get nothing more than a scratch out of all the hammering and cutting of the 5 sided allen plug Nissan chose to put into the middle port.
1 ) Before cutting your standard line- measure up your flaring bar from your Inverted/Double Flare kit and see to it that you have enough room to push a new fitting onto the line, and have about 6.5mm of brake tubing protruding from the flaring bar. This is about all you need to make a proper Inverted/Double flare with the most conventional flaring tools.
Use a line cutter that has special rollers to cut as close to the factory flare, or use a standard cutter and just get as close to a straight section behind the original flare as possible. Carefully Debur the end, and make sure you do not force metal shavings into the line. Fluid should spill out until you cap it, so it should be "self-cleaning".
2 ) put on a standard 3/16 American inverted/double flare nut, commonly found in color purple. This will work with an 11mm flare nut wrench, which should be on the opposite end of the 10mm end that you used to remove the Nissan line from the Z31 BMC.
[attachment=2:3iydi0pf]Inverted Flare Nut for 316in Brake Line 38in-24 (716Wrench) 4pk.gif[/attachment:3iydi0pf]
3 ) flare the end so that it is your standard inverted/double flare (you guys would most likely have this tool, so that's why I made this short guide), and cap the line so fluid does not bleed out.
Take a "Brake":
At this point, you are ready to prep the master cylinder by bench bleeding in a vice with wooden blocks so you do not crush the exterior/housing of the master cylinder with the vice teeth. Follow the rebuilders/manufacturers specifications for the appropriate method. Most rebuilt units come with a small 1 page guide and some plastic fittings to aid in bench bleeding.
4 ) Buy these two adapter fittings:
[attachment=1:3iydi0pf]Bubble Flare Adapter for 316in Brake Line M10 x 1.gif[/attachment:3iydi0pf]
[attachment=0:3iydi0pf]Inverted Flare Adapter for 316in Brake Line M10 x 1.gif[/attachment:3iydi0pf]
5 ) Wrench the fitting using a 13mm box end onto the BMC until it's tight. Don't be a juggernaut. The BMC is aluminum and can be easily stuffed if you force it more than you should. Snug it up, and give it one more jab. That's it.
5-B ) Optional - Inspecting the fitting by removing it and looking at the sealing surface shows that it seals in the same spot as the factory 5-sided allen plug. The 5-sided allen plug relies on the same seat width to hold the pressure of the BMC under all levels of braking. The threads on all brake fittings and plugs associated with this guide are not tapered, so the seal made by the plug and the bubble flare adapter fitting (blue fitting shown in step 4) are equally wide, and sealed to the point where neither will bypass fluid to the threads.
6 ) Bleed your system of air following proper guidelines in the rebuilder's provided guide or in the Factory Service Manual for your model year.
7 ) Go for a test drive. Once a complete test has been done and all air is out of the system- your car is ready for Z32 4 piston front calipers. -
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Special Note:
The inverted flare seat in a brake line or a master cylinder is a FULLY TAPERED bore, and you can only mess up the inverted flare if you flared it lop-sided or if you hate your car. However, the inverted flare seat on the 3/16 GM/American to Bubble or Inverted Flare Metric 1.0 adapter is a different beast. You MUST flare the line shorter than the flares you would normally do. Reason being is that the taper within the adapter on the female end is not a FULLY TAPERED seat. it does not taper right to the base of the threads. It infact has a flat section that basically has the taper machined into it. So if you crank down your arbor on your flaring bar way too tight, you will make the flare seat sit above the actual taper.
You want to have about 2 mm to a maximum of 3mm of tapered seating on the line. 3mm actually may be too much.
I had to cut my line and re-flare it due to fluid seeping passed the inverted flare I made on the line the first time. I used the same flaring technique on the brake lines in the rear and they do not seep fluid- mainly because the tapered seat is a full seat. It extends all the way to the base of the threads.
Keep this in mind when flaring. And don't crank down on your arbor until your wrists break and your palms bruise.
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Finished Product.
26mm Aluminum Calipers painted Iron Grey Metallic with shaved levers + golden coloured slider pins and HP+ Pads, covering 87-89T 26mm Front Rotors.
Goodridge Stainless Lines holding ATE Super Blue Racing brake fluid (one of the best DOT4's with good resistance to moisture contamination).
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Update:
Still running great. Had to emergency stop yesterday due to idiot drivers in front of me.
Held great. Checked the lines when I got to work this morning. No leaking or seepage whatsoever.
Fitting replacement = Great success.
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