49 replies to this topic

[mbolt998]

That old tube nut does look like a metric one. I've been a mechanic for 40 odd years and don't recall seeing a mix of a square back metric type flare with an imperial threaded nut. You need to measure the thread diameter or buy an m10 x 1mm pitch tube nut. If you can screw that in then it's an m10. There is a serious risk of it popping a thread under pressure and an instant brake failure if you put a 3/8" tube nut into a 10 x 1 thread. As regards spanner sizes, a 7/16 af will happily fit on a 11mmhex nut.
We never used copper pipe as, has been said, if it's not securely clipped up it can work harden and fail. I have seen this. Cupro nickel was our favoured type. As for flares, we always refered to them as op1 and op2. If you want a concave flare to match the seating then it's op1 followed by op2. NEVER JUST OP2! I've also seen this and it was weeping fluid. I don't agree with the idea of doing both op's on everything but maybe it just makes it "idiot proof".

 

Thanks. I do have some M10 nuts but the nut I was trying didn't seem to want to fit into them. But I will try with some of the others, get to the bottom of this, and update this thread. Have been doing some bodywork in the meantime while I think about it :)

 

Yes OP2 on its own looks all kinds of wrong. I tried it on some test pieces. So it will all be either OP1 or OP1+OP2 (currently the latter).
 

[mbolt998]

So it turns out this thing has M10 threads for the unions. Actually quite death because the imperial nuts feel like they're going in OK and almost go tight enough. Thank you to whoever it was in this thread who pointed out to watch out for that.

 

 brake_thing.jpg   53.28K   0 downloads

 

My wheel cylinders are definitely all imperial thread (both the old ones and the new replacements from Minispares), as is the junction at the back. This rear brake force limiter thing is metric and I suspect the master cylinder (not original but an aftermarket part from 25y ago) is metric too. It seems to have an M13 or something on the front circuit (I'm just reusing the nut for that one).

 

[mbolt998]

Update to this as I now have the car back on the road and have done about 100 miles. The double-flares are all fine. No leaks, everything works perfectly!

[8mini]

Do you have double flare on the male fitting as well?

[mbolt998]

Do you have double flare on the male fitting as well?

I put SAE double flares on all the pipes (which are all new). That's the only tool I have. I used imperial unions on the wheel cylinders and metric ones on the rear brake force limiter thing (which is metric). My master cylinder also takes metric unions (and one of them is larger than the usual size, so I just reused that union). But the flares are all the same.

 

I also have an inline junction on the pipe that goes to the back of the car. I got a new one of those. But still used double flare on both sides. Basically I think "half-double" flares if you have an SAE tool should never be used.

 

I'm pretty sure my pipe is copper, but Minispares said earlier in this thread their pipes were all Kunifer. But he might have meant their pre-made ones. Or I might have got the pipe from Moss. Not sure. It looks like copper-- I think Kunifer is a bit yellower.

 

The material may matter because how it all squashes up may affect what kind of flares you get away with.

 

The car has now done lots more miles and the brakes work flawlessly.