I discovered my brake line from the master cylinder has been flattened by the previous owner probably put a bar on it for some reason and pried on it.  The brakes still work but I want to replace the line for obvious safety concerns. I have options of replacing the front line only or all of them. And if I do is there any advantage to putting larger lines like 3/8” on instead of the 5/16” it has now?  I’ve thought about a dual master cylinder and update everything. I’m pretty much ready to start driving it in the next few weeks and now I’m contemplating what I should do,any suggestions?

I wouldn’t change to 3/8” line. You’d end up with adapters everywhere, which is just more potential leaks. I’d pull the bad line and see how it looks. If it’s clean inside and out, then I’d check the outside of everything else. But since no one properly maintains (flush and replace) brake fluid like they should, I’d be prepared to find some rust. How the fluid looks will be a clue.

As a last caution. Years ago a a 55 Thunderbird I had the rear line on the rear axle fracture and dump all the fluid. It had worn thru under one of the clamps that held the line to the axle tube. Not visible until the clamp came off. I was going slow in my neighborhood, no big deal. But 2 miles before I was running in traffic and using the brakes. That would have been a disaster. So I’m a big believer in Adele clamps and dual masters.


miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I am very carefull too that’s why I needed parts to make my emergency brake operable. I may have to look at past posts that dealt with dual master cylinder install   Thanks for your opinion  

Replacing the single master cylinder with a more modern dual system is never a mistake if you drive your car often. Easy enough to convert back for the purist and a lot safer. Also as you mention the emergency brake is often a life saver.

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Hi  Are you sure lines a 5/16?  Pretty sure mine are 3/16" Easy to fix in shorter sections, pita  to do full  front  to back  axle in one section.

Thanks for correcting me on that ,I don’t know what I was thinking. The brake  lines are sure small I thought they would be bigger than that