Last year I installed some ZZP rear flexible brake lines I had put off for entirely too long. I couldn't get the new lines to thread into the OEM hard lines on the rear(body to A arm, and A arm to caliper). I was able to do the fronts years before and it was cake.

I somehow, was able to complete the passengers side, on the drivers side I was only able to replace the line from the A arm to the caliper. I for the life of me could not get the ZZP line threaded into the hard line from the master cylinder.

Here is my question, what is the OEM thread on the brake lines in the rear? The hard line leaks from the master cylinder to the OEM brake hose, and its as tight as it can go. I've heard its M10 x1.0mm but I have no way to verify.

I was going to cut the fitting off and replace, but I would like to avoid that if at all possible since there is zero room to work on anything. I also see that Permatex makes a brake line sealant, anyone have any luck with that stuff?

Any insight would be appreciated!

 

I had a very similar problem. I bought a set of FTP stainless steel brake lines. I installed the fronts with no problem, but I couldn't get the rears to go at all. It always **** to the side like it was going to cross-thread. I was certain the threads were a different size, but I had no way to verify it. A year or so later, I bought a set of Goodridge stainless steel brake lines, thinking that a well-known company like them would have the right fittings.... I only tried installing the rear lines, but had the same problem. A few months ago, one of the front FTP lines burst, so I swapped in the Goodridge lines. Since I was working on the brakes, I figured I'd give the rears a shot again. Same problem with the fittings trying to cross-thread, so I figured I'd just try screwing the flexible axle lines onto the fitting for the caliper line, AND IT WORKED! Thoroughly confused now, I put the correct line on, and it installed just fine. After some more investigation, I found out that the first circle of threads on nearly all my brake fittings was squashed slightly, preventing the flexible lines from screwing in properly. I took a tiny triangle file and fixed all the fittings and they all worked fine after that.

I also considered cutting off all the fittings and installing new ones, but I've never flared brake lines before, and I read a lot of bad stories about how hard it is to get a perfect flare.