65StangFB

Does anyone put anything on the brake line threads when connecting the lines to blocks or cylinders. I have replaced all line and cylinders (Master and wheels) and I started to do a brake bleed last night and notice a bad leak directly out of the MC connection to the main brake line. I thought those lines tightened down to a seal, but maybe thats only on the whel cylinder or disti blocks. Can anyone help. Are you supposed to put anything on the threading of these connections? Thanks again for your help.

dozierstang

If they are stainless then I put a dab of anti-seize on the threads, other than that, nothing. The seal on the brake lines are at the flare. You may have a piece of trash between the flares, undo it, clean it good then snug it down good.

65StangFB

Thanks. Yes they are stainless. I only inspected the engine compartment and the disti block looked good, but not the MC. It almost feels like the line going into the (NEW) MC keeps tightening down. Would it hurt to use some nylon or RTV?

66 Restomod

If the hard lines are new, they should be doubleflared. When you tighten them down the first time, they do crush a bit as the doubleflare takes its permanent shape. This is needed to stop leaks since the system will be under so much pressure when you step on the brake pedal. You shouldn't need or use anysealant here.

dozierstang

+1, Don't use sealant here. Only anti-seize, as if you were to pull the line later on, it prevents galling. Tighten it down snug, if it leaks then snug it a little more. Stainless is harder than carbon but galls much, much easier.

This is a lesson, if you put any stainless bolts, lines, etc.on your car, use anti-seize. You will be much happier when you decide to pull the part and you don't have to drill out a stainless bolt. Trust me, stainless is a booger to drill, cut, etc.

65StangFB

Thanks Dozier. I will continue to work on it. Like I said it seems the line wont tighten on the MC. I may end replacing it if it appears the threads are stripped. They dont appear stripped because the line keeps tightening down but doesnt ever feel tight. Thanks everyone.

gothand

Loosen it up several turns, push the line in straight and hold it in place and then tighten it back up while still holding the tube. If you allow the nut to pull the flared tubing in, sometimes it will come in at a little angle and not allow it to seal property.

JMD

[:@]Shi* ---- just lost this post to the ether,,, ok once again....

There are two prominent issues that may be giving you problems....

Some master cylinders are not set up to accept brake tubing directly. On these, you need to use an adapter from the port of the master cylinder, (pipe threads) to the style of lines you are using, (flare or inverted flare, more on this below). Master cylinders that require this are usually of the aftermarket variety, but not always. You can look into the ports of the master cylinderto see if there is a cone shaped device inside for the end of the line to seat on.

<<There are some master cylinders that require special fittings (adapters) that utilize copper gaskets between the fitting and the M/C body,, instead of the "pipe threads" as mentioned above>><edit>

It has always been my understanding that stainless brake lines are assembled using standard or "single" flares. This is done because stainless is too brittle to use the inverted flare (double flare) method. Inverted flare is the standard used on brake lines. If your master cylinder is set up for inverted flare, and you are trying to install standard flare lines, you will have two issues, the threads on the end of the brake line will be wrong, and the line will never seal because the pitch of the flare is different. Again, adapters will be needed.

Brake plumbing sucks.... there can be many variables...[:@]If your lines are not compatible with your M/C, consider yourself fortunate that the fittings would not tighten up.....

You can find these adapters at a well stocked parts store that deals with lots of comercialmechanics etc, you will probably not find these at an "autozone" type establishment.....

65StangFB

Thanks guys. I do have to tell on myself though. I had to go to a local parts store at lunch and took a look at their lines from the MC to disti block and it appears one side of the line has longer threads. I will check tonight, but if I have this line switched then that would explain why the MC side is not tightening down all the way.

I will also keep in mind the details you all have explained as well and apply them. Thanks

JMD

Hopefully, it will be that simple,,,,