Topic: What is the purpose of the copper front brake line?

[Tugboat]

Why not just run a hose from the switch to the caliper?

[bryanj]

Stops the hose flopping into the spokes

[Don R]

 It has been done.

[PeWe]

There are sets like that. MC- pressure switch-caliper.
The old metal pipe is not used. I ordered on eBay:
Goodridge FRONT SS BRAKE Hoses HONDA CB750 K1-K6 76-77.

The Honda pipe is slimmer and is routed nicer to caliper.
I changed to the metal pipes when I added dual brakes. The line to right caliper has less space than left.

[web]

These are the rubber hose days. Keeps flopping and flex down.

[gtmdriver]

I did it on my CB350F.

I have a single braided hose running from the switch block to the caliper. I still run it through the original wire clip and rubber grommet so there's no danger of it chaffing anywhere.

[Bankerdanny]

Why not just run a hose from the switch to the caliper?

You can. Many companies sell a replacement hose to convert to a single line. I think the reason for the hard line on the K models and early 750 F's is that the caliper is mounted in front of the fork leg, so the hard line helps reduce the risk of the line rubbing on the tire. The 750F 2 and 3, which have the calipers mounted behind the fork leg like modern bikes is a single line setup.

[PeWe]

Steel braided lines might be a newer alternative not available when the old CBs were produced?

[robvangulik]

I put teflon/steel braided lines on my Honda's in the 70's and 80's.
And the 2018 CBR1000RR Fireblade still has rubber brakelines from the factory....

[PeWe]

I put teflon/steel braided lines on my Honda's in the 70's and 80's.
And the 2018 CBR1000RR Fireblade still has rubber brakelines from the factory....

Good to know. I bought longer stock looking rubber to my K6  with higher bar and longer fork back in 1980.
Did not see nor heard about anything else.

Rubber for the feeling or saving the seals due to SS harder function?

[robvangulik]

Rubber for the feeling or saving the seals due to SS harder function?

Cheaper to produce probably?

[madmtnmotors]

If you have "copper" brake lines then I suggest replacing them with either hard steel pipe or flexible hose purposely designed for brake hydraulics. Copper does not stand up well to the crushing forces in a flare fitting and they also tend to crack under vibrational stress. I believe copper is also forbidden for fuel line application in many places for these same reasons.

[mark ward]

Wilbur, i have experienced the copper flair-fittings issue..... Too soft, I guess.

[bryanj]

Copper pipe is not normally 100% copper but an alloy of copper and nickle (i think) trade name "Kunifer"

[web]

Yup. Which does not have the cracking issues. Good stuff, common in car restorations too. Lasts pretty much forever if properly supported and not loosened an re tightened a million times.

[scottly]

Hard brake lines are made from "double wrapped" steel, not copper or any alloy of copper. It is double-flared, while copper pipe will crack if a double flare is attempted.
As to the original question, I have no idea why Honda thought it necessary to have a piece of hard line connected to a moving caliper, or why they used the adjuster screw and spring; no other disc brake I've ever seen has used these!?? Honda abandoned both on the F2/F3 upgrades and all subsequent bikes... 

[web]

Scottly look into cunifer uses and then again at that stock hard line on a CB front, that stubbornly refuses to rust 

It's amazing how far you can change metal properties by alloying it. Wouldn't touch a pure copper brake line indeed!

[pjlogue]

I replaced my hard line portion with the copper-Nikle alloy.  Works well and polishes up beautifully.  I tried stainless but forming the flair was impossible as it was too tough to work with on a hand flavoring jig.  Have had no issues with the copper-Nickel line and it was easy to form the bends needed around the lower fork leg.

-P.

[MauiK3]

Copper nickel alloy is also known as Monel, used a lot in marine applications. My hard lines are monel.
There is a super version of the alloy called K-Monel that is copper nickel aluminum. Believe it or not it makes
some of the strongest nuts and studs you've ever seen and it does not corrode. Great stuff.

[Don R]

We removed a boiler with a cooper-nickel heat exchanger. Yes, the guys called it cooper nickel. The scrap guy was delighted to get it.
  My 2003 GMC dually has badly rusted brake lines, making my own lines with copper nickel tubing was an option because it flares beautifully and lasts as long as you need it to. Instead I purchased a pre made SS kit with new fittings already installed but I'll need to remove the bed so I'll probably get a new fuel pump and fuel lines at that time too.

[HondaMan]

Copper nickel alloy is also known as Monel, used a lot in marine applications. My hard lines are monel.
There is a super version of the alloy called K-Monel that is copper nickel aluminum. Believe it or not it makes
some of the strongest nuts and studs you've ever seen and it does not corrode. Great stuff.

Now, THAT sounds like a great idea to tell everyone who has these bikes in Hawaii and Florida. I get many parts (even whole bikes) from those areas that needs something less corrode-able.