Cunifer, short for copper-nickel-iron, is a brake line material made from roughly 90% copper and 10% nickel, with a small amount of iron and manganese added for strength. It’s sold under a few trade names (Cunifer, CuNiFe, NiCopp), but they’re all the same underlying alloy, and all a step up from the plain steel line most vehicles ship with from the factory.
Why copper-nickel instead of steel
Steel brake line rusts. That’s the whole story, road salt and moisture get at it from the outside, and eventually a line that’s held up for years fails at a corroded spot, often exactly where it’s hardest to inspect. Copper-nickel doesn’t rust the same way. It’s the material most commonly reached for on a car that already lost a factory line to corrosion, and increasingly what gets used on a full brake line replacement from the start, corrosion-prone climate or not.
It also behaves better under a flaring tool than either of its alternatives. Pure copper work-hardens fast, bend and flare it more than once or twice and it gets brittle enough to crack right where you need the seal most. Steel doesn’t have that problem, but it takes real force to bend and flare by hand. Cunifer sits in between: it flares cleanly with a standard tool, doesn’t harden against you the way pure copper does, and takes noticeably less effort than steel to bend into a clean run.
Fittings and flares
Cunifer isn’t a special case at the fitting end. It flares to the same standards as steel line, SAE 45° double flare or ISO/DIN bubble flare, depending on what the vehicle calls for, and takes the same fittings. Nothing about switching to copper-nickel means sourcing different hardware for the rest of the brake line.
What we stock
BrakeQuip Products carries copper-nickel line as BQBRAKETUBE, sold in the common brake tubing sizes. If you’re building or replacing a full line and want the material that isn’t going to be the reason you’re back under the car in five years, this is it.