Master cylinder brake line size / fittings

[Schwifty Rich]

2003 Rubicon

TL;DR
[rounded a brake line fitting and it seems the old is bigger than 3/16.
can I still use 3/16 or should I try to match the previous size? Help on identifying it? Also any help with fitting identification/verification is appreciated]


So in the process of doing a brake job ( rotors, pads, calipers) I accidentally let the master cylinder run dry while bleeding

That being said I decided I have to bench bleed the master cylinder in order the get the air out and finish the bleed. Well, one of the fittings from the proportion valve to the master cylinder (master cylinder side) became rounded as I was removing it (with a flare wrench).

Looks like it’s time to learn how to flare brake lines, yippee!

doing some research and playing with the fitting size finder at the auto parts store it seems the lines I need are 3/16 and the fittings are 1/2 - 20 and m12 -1.25

(PLEASE CORRECT ME IF IM WRONG


I couldn’t find a suitable replacement for the fitting on the proportion valve side so I figured I’d reuse it since it was still in good shape. That’s when I noticed the problem.

it seems the previous owner did some things to the brake lines and the ones installed are slightly bigger.

I took out my caliper to verify what my eyes saw and sure enough the old lines are bigger and the old fitting doesn’t fit as snug as it did on the old line.

Can anyone verify the size of these lines on a stock wrangler? I read online sometimes these small lines between the cylinder and proportion valve can be larger than the other lines used.

If the previous owner did use a larger line, it seems it’s not 1/4 inch which was my guess. Can anyone chime in on the size?

Can I still use the 3/16 or should I try to keep what was on there?

 

[Rubicon88]

There are no metric 1.25 threads used with 3/16th line or the factory metric line equivalent.

Make new ones..
Use 3/16 line
Nickel copper works well especially making a lot of bends or tight bends. You can make them with your hands.
The MC fittings are
M12x1.0 and M10x1.0 and they are a bubble flare

 

[Schwifty Rich]

There are no metric 1.25 threads used with 3/16th line or the factory metric line equivalent.

Make new ones..
Use 3/16 line
Nickel copper works well especially making a lot of bends or tight bends. You can make them with your hands.
The MC fittings are
M12x1.0 and M10x1.0 and they are a bubble flare

Thanks for the confirmation!

So I have been practicing my flares with the hand tool you can rent from the auto parts store and I got one fairly good bubble flare but my double flares are lacking. I went out of my way to rent the same tool from 4 different stores trying to find a quality one that wasn’t busted up from previous uses. I finally gave up and bought one of these tools. I’m crossing my fingers in hopes this creates perfect flares.
I also ordered some nickel copper lines to work with rather than the steel. Time to get this stuff done!

Titan 51535 3/16-Inch Double Flaring Tool https://www.amazon.com/dp/B06XPRVCPV/?tag=wranglerorg-20

 

[BC Moto]

Not trying to thread jack but im looking for the rear brake lines for my 03 and i see they are discontinued so I was wondering what everyone else is doing. This is for a drum brake on a dana44

 

[Schwifty Rich]

Not sure how the drum brakes work, but I would make new hard lines if I were you. I know my rear brake hoses and hard lines come from the factory as one piece so if I ever want to replace the hose I’ll have to make new hard lines and connect it to new brake hoses.