Master Cylinder Experiment

[Mister 4x4]

I had some stop-leak issues with my new brake lines. I remember ordering them from Inline Tube, and went with the standard brake lines, thinking that if the standard brake lines in my car had lasted that long, that stainless was more or less a waste of money. I think I remember reading something about the flares on stainless lines being super hard to get seated as well.

I'm not entirely 100% sure, but I'm thinking I might've wound up with stainless lines, because I had Hell getting them to seat on all new fittings. The lines were pre-flared (you'd think that professionals would make good double-flares) which I further de-burred just to make sure. I installed everything "as normal" (roughly 25-30 ft-lbs) and filled it up to begin gravity-bleeding. Once I got all of the bleeders closed back up, I noticed brake fluid seeping from every flare fitting in the system. I had to torque every fitting beyond reasonable specs to get the lines to seat and stop leaking - I'm surprised I didn't crack any of the flares or strip anything out.

Suffice it to say, I am not a fan of stainless lines either.

 

[72HCODE]

I broke 2 prop valves installing stainless lines. stainless does not give an inch and the double flairs do not stretch to seal on the cones.

that right there should of been the indication to stop but i felt stainless is the way to go.

i spent about 5 months chasing down leaks from all the different fittings around the brake system.

it was a disaster from day one, i wish i never checked stainless when i ordered my new brake lines 10 years ago.

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then after that i still had weep leaks from the rear cylinders and the master.

i swapped the master 3 times, and i swapped the rear cylinders 2 times.

i had a never ending weep leak from the disc fitting on the master and last year i made my own brake line and bought a double flair tool and replaced the stainless from the master to the prop block that solved that leak and what do you know seating mild brake lines was like butter it sealed instantly with very little torque on the fittings.

but the dot 5: At this point i expect to see leaking in the rear cylinders again when i get to them.

the only saving grace of Dot 5 is it will not eat paint, but if it just keeps leaking whats the point.

a modern brake system with tight tolerance would be fine designed for dot 5.

but we are dealing mostly with 40 year old rebuilt parts with loose tolerance and poor re-manufacture in either china or mexico, so of course it will leak unless the o-rings swell up all the time.

I'm just so aggravated, i tried everything and i just cannot undo some mistakes they just keep coming back again and again.

so stay away from stainless lines and dot 5 do your sanity a favor.

 

[midlife]

I used DOT 5 in my 66 Mustang, with new brake components, all except the prop valve. I had to re-tighten a few joints, but it never leaked after that. I was very happy with the DOT 5.