Originally Posted by Dan Stokes

Nobody wants to hear me say this but here goes.......

Again, a trip to your Parker or Swagelok store. Get an INSTRUMENT GRADE compression fitting and be done with it. DO NOT head to the hardware store - hardware store compression fittings are worthless and WILL leak or even blow off at as little as 50 PSI. Instrument grade compressions are good for 2200 PSI and probably even more - way more than your brake system uses. This will make a permanent and safe repair.

I put my booty where my mouth is on this one. My '78 Cadillac Fleetwood lost a line and the way it was run it was almost impossible to change it out the "proper" way so I procured one of the fittings mentioned (I used them all the time for toxic gas plumbing at work) and did the deed. I later sold the car to my bros GF who used it for an airport limo - no issue up to the time she sold it for a newer model (several years). It never leaked a drop from that spot.

Stand back for all the replies from well-meaning folks who have no idea of the type of fittings I'm referring to - happens every time I post up about this. I'm NOT recommending this fix - just saying that it works.

Dan

Originally Posted by Zulfiqar

there are two kinds of bubble flare, one is a DIN or ISO type bubble flare like you see on MB, BMW, Chevys etc. The other is the ancient SAE bubble seen in morris and other british brands.

The ISO type requires a specific tool to accomplish and is not available usually at brick and mortar parts stores. Amazon has an OTC brand which is pretty good, or if you have a good vice you can buy the little cube and insert by Kent moore which are GM original service parts.

If you are running out of line, remove the line till a good servicable end like the ABS pump and install new line - the new green armor clad line is exactly the color of MB line and is also available in upto 7ft lengths with proper bubble flares and nuts. Or you can get some cunifer line from NAPA, a pack of nuts and bubble flare it yourself.

You can also sort of ham it with a larger line and make a spring like coil in between to shorten it to size. The bending tool at harbor freight is a good item for this.

a word of caution in bubble flares. It takes practice on atleast 5 or 6 flares to get the hang of it - bubble flaring requires lubrication on the flare to not damage the tooling and not damage the flare face. (use silglyde - dont worry its compatible with brake fluid, which you will be bleeding out anyway)

for bending - practice on some scrap line to get the hang of it - cunifer bends like warm wax compared to steel line and is extremely long life.

Do not fall for the "bubble is half double flare" - you end up with an SAE bubble, the SAE bubble flare of british cars used conical nuts like double flares, the SAE bubble also is narrower compared to the proper DIN/ISO bubble and using it with a DIN/ISO nut will make it let go under hard stop braking pressure.

Originally Posted by Zulfiqar

compression fittings on brakes are not legal in all states - best check on that first.

Originally Posted by Dan Stokes

Those laws were passed in response to the use of hardware store fittings which have a barrel-shaped ferrule - these are the ones I cautioned against. The instrument-grade fittings I'm talking about have a wedged cone shaped ferrule and they WILL NOT blow off or leak as long as they're installed on cleaned tubing. As mentioned, good for 2200 PSI plus.

But technically a compression repair IS illegal in some states because the lawmakers don't know the difference. And as I said I'm not advocating this repair, just saying that it works.

Dan