Brake line flare fittings

In the past I have bought braided brake line kits and found that they use a "universal" or "dual seat" flare which supposedly works with any type of mating flare.

The factory Nissan hard lines seem to have a very similar shape to this flare, with a ridge at the same diameter as these dual seat fittings - so they're basically just butting the ridges together and not seating in the conical area at all.

Suppliers seem to just say "they work fine" or "no one else has complained"

I successfully hassled one supplier of these lines ages ago and after a year or two they made some with the correct flare fitting for the Nissan lines - which I have been using ever since.

I just picked up a set of D2 brakes which come with lines, and they have the universal style flare (photo attached)

I would use my old lines but the caliper end is different.

Has anyone else seen this or had problems with them?

I'm amazed that these all claim to pass all the relevant standards for road use worldwide.

Sounds like the factory hardlines have a bubble flare? could you send a photo of that end?

You could re-flare the end of the hardlines to a double flare which would be a bit stronger anyway

This is what the factory lines look like.

Last time I ran into this issue I measured them and the edge of the conical section was the same diameter as the ridge in the aftermarket fitting.

I'd rather not re-flare the factory lines since they work well and are the right length.

I also don't have tooling that would do anywhere near as good as job as Nissan does :)

The correct fittings are definitely available, it just seems that most people use the universal one.

ok I was able to measure both of these, and the Nissan hard line has the ridge at 6mm diameter, and the fitting on the D2 braided lines has the ridge just under 5mm - which leaves enough overlap that it should work, but I think it's far from ideal.

You can actually see a mark in the flare on the left side of the picture where the overlap was when they were previously installed:

Last time I ran into this issue the ridges were at the same diameter, so this set is probably just usable, but I think I'll try to get the right ones anyway.