Re: Cu-Ni vs. Steel for brake lines

Posted by BH On 2011/6/24 12:20:23

What has been referred to as "Cu-Ni, here, is perfectly legal for state inspection in PA, as I believe it is only a copper-nickel (electroplated) coating over steel. In fact, the part number was prefixed "CNC-", which I took as an abbreviation for "Copper Nickel Coated". It's been a couple of years since I've used the stuff, but it was only available in 25-foot coils of 3/16-, 1/4-, 5/16- and 3/8-inch diameters then.

I didn't care for the coated steel tubing that had been available previously, which was covered in a dark green polymer(?) material. It didn't seem fit in the flaring dies, and I also noticed the coating crack at the flare, which is a point that often leaks due to rust.

In contrast, the copper-nickel coated tubing fits the flaring tools the same as steel and is easier to bend. However, bulk coiled (non-coated) steel tubing is also easier to bend than the pre-flare straight lengths of steel tubing.

As I've routinely seen factory-formed steel lines rust out in much less than ten years around these parts, the copper-nickel tubing is a worthwhile investment for a daily driver.

However, I prefer to purchase 25-foot coils and/or pre-flared straight lengths of the plain double-walled steel type, as needed, for "recreational" vehicles and bend 'em myself. The key is to find some good bending tools. I have one for general purpose bends, but another that is specially made for tight bends.

Yet, just prior to installtion, I also like to pull the nut (fitting) back from the flare and apply a thin coat of Lubriplate to the outside of the tubing to help prevent rust that normally causes things to seize, later.