Brake Pipe Flaring
Figure 1. Moprod pipe flaring tool, cheap
but very effective bit of kit.
Figure 2. Snap-On flaring tool, the 3/16"
die was missing so I couldn't show a flare done using this tool.
|The brake pipe flaring tools usually
seen are similar to figure 2, these are fine if you want to
do several sizes. But the flares produced are not symmetrical,
sometimes they need to be wound on to a hard seat to reform
them so they seal and they are a bit more fiddely to use under
a car than the tool shown in figure 1.
||The tool shown in figure 2 cost
about £20 the tool in figure 1 £3.50. As supplied
the flaring tool comes with another casting that bolts to the
2 blocks, the 2 holes through the two blocks are threaded 5/16
UNF, The other casting is meant as a handle, but I usually use
it in a vice and I lost the handle, so I use an old alternator
bracket as a handle if I am going to use it in situ.
Figure 3. Moprod tool in action, if possible
I use it in a vice.
Figure 4. Tube in flaring tool ready to
|The threaded die has one end formed
for single flares and the other end formed to collapse a single
flare, figure 7 shows the stages of flaring that corresponds
to figures 4, 5 and 6.The groves machined in the threaded die
are for pipe-die depth setting. When the single grove is in
the position shown in figure 4
|| the pipe is the correct depth
in the die for a single flare; you can still see the groove
when the blocks are bolted together. The other end has 2 grooves
I just ignore these and collapse the single flared pipe as far
as the die will screw in, the single flared pipe is in the position
it was left in after being flared
Figure 5. Single flare formed.
Figure 6. Die reversed and flare collapsed,
|A pipe cutter is a good idea if
your doing very many brake pipes, I have a Rothenburg pipe cutter
its like a miniature plumbers wheel pipe cutter. However I couldn't
find it so I had to use a hacksaw. Figure 7 has a sawn piece
of pipe a single flare and a double flare. When you cut the
pipe try and cut it square,
||use a file to square and clean
the end up, also remove burrs inside the pipe. The pipe used
for the single flare in figure 7 looked like the sawn end shown,
the double flare still had some burrs in the end of the pipe
you can see what's left of them in side the double flare.
Figure 7. The three tube ends, left to
right: plain, single flare and double flare
|I didn't use any lubricant when
doing these flares, they look a bit cleaner when the ends are
lubricated with brake fluid. You don't want any traces of oil
in your brake system it destroys the type of rubber used in
brake seals. Someone asked about Flare nuts and the difference
between metric and imperial, the two types are shown in figure
|| On the left are the imperial ones,
3/8 UNF On the right are the metric ones, 10 mm these do come
in several different pitches is it 1.25 and 1.0 mm I am not
sure and it is very rarely that we ever need the not so common
one. I buy these in boxes of several hundred[500?]they cost
about a fiver a box, I have no idea how much single flare nuts
Figure 8. left are male and female imperial
flare nuts, right are the metric counterparts. Sometimes you
will find fittings that look different to these, I think Yank
imperial fittings have a much shorter unthreaded bit.
I did have a turret brake pipe tool, it wasn't the one you
see in the draper/sealy catalogue's but a rather nice old
Churchill thing. It made perfect flares in everything I ever
tried in it, including 5/16" stainless steel. Someone
wanted to buy it and this tool does the job so well that I
said OK. The Snap On tool does the job but not as well as
the other tool, under a car flaring steel pipe can be very
difficult. Usually a pipe with a male union going into a cylinder
will have a single flare, but sometimes a hardened convex
seat is in the cylinder, so that a double fare will be needed.
So check the old pipe before flaring the pipe.
|Something to always remember is to
check the pipe union is on the pipe before flaring the pipe,
I still forget now and again.