brakes FIXING CROSS THREADED BRAKE PIPE FITTINGS

[JayMac]

Making some progress on my fixer upper and it is a good feeling putting some part back on the car versus taking them off. Found out I suck at blogging but do enjoy the post others make to share their efforts. While I was putting the rear end back in I cross threaded one of the rear brake pipe fittings on the rear of the car. I looked at all of the options and before I decided to pull the junction fitting above the driveshaft I decided on the following steps of action:

Determine which threads you have damaged, male , female or both. Since I have the front pipes off I had access to male threads but I needed to find out if they were good. I could check the hose(female)threads simple by threading in the front pipe fittings to the rear hose. If you have a metric bolt that is the correct thread you could use that but good luck with that one as it is a pretty rare thread. M10x1 is what you need. Most places have 1.5 or 1.75 and most die and tap sets don't have the M10x1 thread tools. So you can order one on line for @$20 or you can go to your local auto parts store, mine is Advance. They carry the M10x1 nuts but no bolts. Since the hose end seams to be a harder metal it will probably be the male threads on the pipe fitting that are damaged. I took the nut and coated the threads with antiseize to work as some sort of cutting lubrication. The nut requires a 17mm wrench or socket. The male fitting should be an 11mm wrench. For this you do not need the proper flare nut wrench but this might be part of the reason you are in this situation in the first place. Mine was simply to being sloppy and in a hurry to finish this in the time allowed. Anyway, after threading the front pipe into the hose I knew the hose was good so I starter the nut on the pipe fitting and slowly turned it by hand until I hit resistance. Once I found that I slipped a 17mm box over the nut and used the flare to tighten the fitting into the nut less than 1/4 turn at a time. I loosened and tightened a bit more in each series of turns slowly working my way through the damaged area. As the resistance started to fade I switched over to a socket and slowly wound the fitting all the way down into the nut repairing the threads. It should be mentioned that if you choose to use the box wrench you need to put it over the fitting first before you start threading the nut. Hopefully you never have to do this but if you do this worked well for me.

[Simeon]

Not going to be preachy about this but I am not sure I would trust threads re-swaged in this way (the thread is not cut). Not on something as critical as brakes. That thread needs to hold the flare tight against the corresponding taper inside the fitting. You don't know if that is going to last under vibration.

You sound like you went into it with your eyes open. Just saying it's not something I would do.

Brake unions and head bolts should be capable of being wound by fingers alone until they bottom out. If you meet any resistance stop and wind it back out. If you can (the pipe doesn't always let you) push the flare into the bottom of the port so that the thread as it is tightened doesn't have to pull the flare into position.

[M3M3]

craftsman and others make thread cleaner kits.  sort of like tap and dies, but they do not cut, they just form threads.  everyone should have one of those kits as part of their tool box, especially when working on old cars with old fasteners.

 

nice save.   for a brake line i would have just replaced the fitting or the line. 

[JayMac]

I thought about replacing the line but in my opinion there was no need for it if this worked. This was not a fitting that got put on an threaded all the way on cross threaded. It was damaged very high on the male thread. I would not have minded replacing it as I do have new pipes for the fronts waiting to go on. What I measure was damage to the existing parts, my ability to cut and flare the existing pipe (which would have been the second choice), or putting on a new pipe. I weighed each and factored in that I bought this car as a project and that these things may and will come up. Not saying it is correct but I am not worried in the least bit. Write up my make it sound more dire than it was. I just go forward and back because that is how I tap something and thought it was not only correct but made sense to me which is what I use for the litmus test.

[JayMac]

As an update this turn out to be a fail. When I inspected the male fitting it appeared to be good and when I tested the female (hose) I was able to get it all the way on. Both of you guys had great points so I took a closer look. While I was able to thread the nut on the pipe, the hose fitting actually had a thread that was messed up. It was pretty far in so it threw me off but Simeon's comment about ease of coupling made me look at it closer and the comment about replacing the hose was driven home by the date on the old hose (March 1992). So I will reload with new hoses. Thanks for the comments as it made me go back to look it over one more time!

[Hans]

I got a comprehensive thread chasing kit on Amazon. Not to be confused with tap and die sets that actually cut threads. These are handy for cleaning and make minor corrections to old threads. As mentioned above, I would not take a chance on iffy brake line threads. This is one place you do not want to force a fitting into place.

[JayMac]

That is kind of the direction I was going for. I have a tap and die set, I have a set of thread chasers but the m10x1 thread is what was kind of an odd nut. Did your kit have that one? It would be nice to have one ( a kit) that has all the items needed for our cars. When doing research for this I stumbled across a couple of threads on Corvettes that claim the newer cars come from the factory with hoses that are cross threaded. My situation was self induced due to bad lighting and being in a hurry to finish up. In the end new lines will be better for me or the next owner down the line. Thanks for the info on the kit if you have it.