johnH20
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| posted on 28/3/15 at 01:47 PM |
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Brake unions - how tight?
Battling with my newly completed brake system, it seems to leak at most of the unions. Flares were carefully made with a good quality tool, used a
pipe cutter not a saw on the pipes and carefully checked for swarf etc. How tight should the unions be? I know this is a bit like ' how long is
a piece of string ' because you cannot get a torque wrench on there only short open ended spanners. Is it a case of max force - I am not
particularly strong. Also what are the possible defects in the flares and or unions I should look for. Any advice appreciated.
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Dooey99
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| posted on 28/3/15 at 02:00 PM |
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go for FT (fucking tight)
use a standard length spanner and just got really tight. thats how i do mine 
Less weight more speed, more power more speed
If in doubt, give it a clout
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corrado vr6
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| posted on 28/3/15 at 02:08 PM |
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Have you done the correct flare? Sometimes you need to do a double flare depending on what your attaching to
http://r1indy7.wordpress.com/
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designer
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| posted on 28/3/15 at 02:42 PM |
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I too would say the flares are wrong.
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theduck
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| posted on 28/3/15 at 03:07 PM |
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As above, need correct flare shapes.
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rusty nuts
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| posted on 28/3/15 at 03:37 PM |
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Even when using a mini pipe cutter I always use a file to make sure there is a clean cut on the pipe before flaring. Make sure that you are using the
correct male and female dies. imperial flares are different to metric as well as single or double although I have seen imperial flares on metric
fittings being done without any leaks. Doing the fittings up FT is plain stupid as you run the risk of stripping the threads on the nuts etc .
Can't remember ever having any leaks in nearly 50 years in the trade
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owelly
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| posted on 28/3/15 at 04:47 PM |
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Are you using the correct unions? Are they long enough to squish the flare before bottoming out? Is there a gap between the underside of the hex and
the bit it's screwing in to? Is it the correct thread?
I've never had to swing on a brake union to get it tight enough to hold fluid! Usually, you feel the union touch the flare and then another half
a turn will pinch it enough to hold it.
http://www.ppcmag.co.uk
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steve m
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| posted on 28/3/15 at 04:53 PM |
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As the guys have said above, I also have made my own pipes for years, and still "dress" the flare with a file to clean up any burrs
ive never had every one leak massively, and If I did, would never make one again!
but any small weep, just nipped up with a spanner,
FT will not work, brake unions are not strong, you will strip the threads,
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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johnH20
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| posted on 28/3/15 at 05:18 PM |
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Thanks for the input so far. I am using the CBS flaring tool which forms male ( bubble ) flares and double female flares. I am not sure whether these
are SAE or DIN spec or indeed something else. I did not find them difficult to form and was happy with the quality otherwise I would not have used
them. Still not sure how I could have gone wrong. Most of my hardware is generic mostly from CBS I think but I have some flexis with Aeroquip
fittings.
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Irony
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| posted on 28/3/15 at 05:34 PM |
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I was unsure so i just nipped it up. I pressurized the system using a ezzibleed and you couldhere the leaks bleeding the air out
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Smoking Frog
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| posted on 28/3/15 at 06:08 PM |
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I made all my flares with a cheapo tool, I did have one union which did weep and further tightening made little difference. I think if you have the
same problem redo the flare. I found it best not to put excessive pressure in creating the flare but spanner the flare up in a spare union mounted in
a vice and brake fluid for lube.
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rusty nuts
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| posted on 28/3/15 at 06:23 PM |
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quote:
Originally posted by johnH20
Thanks for the input so far. I am using the CBS flaring tool which forms male ( bubble ) flares and double female flares. I am not sure whether these
are SAE or DIN spec or indeed something else. I did not find them difficult to form and was happy with the quality otherwise I would not have used
them. Still not sure how I could have gone wrong. Most of my hardware is generic mostly from CBS I think but I have some flexis with Aeroquip
fittings.
If you look at the angle at the back of the flare where the straight section of pipe is imperial flares it will be about 45degrees , a metric flare
will be a right angle .
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britishtrident
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| posted on 28/3/15 at 06:52 PM |
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If you have metric fittings you should have DIN flares but generally using an SAE flare in a DIN fitting or vice-versa won't cause
problems provided the flares have not been formed undersize.
Officially all DIN standard flares should be convex not a concave-convex double flair BUT in the real world car manufacturers use them in
female fittings particularly in pipe to pipe splice joints and connections to some brake hoses.
A concave-convex DIN flare won't seal where a simple convex DIN dome flare is required and vice-versa.
So it looks either you flares are not generously enough sized or you are using double flares where single should be used.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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johnH20
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| posted on 28/3/15 at 08:56 PM |
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Interesting comment British Trident. I have read that one should NEVER use single flares on high pressure ie brake systems. I am obviously not an
expert so not sure how to treat this info.
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tims31
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| posted on 28/3/15 at 11:23 PM |
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quote:
Originally posted by johnH20
Thanks for the input so far. I am using the CBS flaring tool which forms male ( bubble ) flares and double female flares. I am not sure whether these
are SAE or DIN spec or indeed something else. I did not find them difficult to form and was happy with the quality otherwise I would not have used
them. Still not sure how I could have gone wrong. Most of my hardware is generic mostly from CBS I think but I have some flexis with Aeroquip
fittings.
I used the CBs tool to and so far had no problems with my brake system leaking although I haven't run it yet but the brake system has been
installed for over 6 months and no leaks...yet.
Again used a pipe cutter, cleaned the end before flaring, formed the end and just tightened up to a normal torque not over tightened.
HTH
Build: http://www.martinsfurybuild.co.uk/
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rusty nuts
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| posted on 29/3/15 at 06:36 AM |
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quote:
Originally posted by johnH20
Interesting comment British Trident. I have read that one should NEVER use single flares on high pressure ie brake systems. I am obviously not an
expert so not sure how to treat this info.
Most if not all flares on your tiptop will be single flares on male brake pipe fittings .Are you using double flares instead of single? Look at the
shape at the bottom of the female components and use the correct flare. Female brake pipe nuts normally use double flares
[Edited on 29/3/15 by rusty nuts]
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britishtrident
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| posted on 29/3/15 at 10:06 AM |
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For anybody buying a brake flaring tool the best one under £100 is the PowerHand on car tool which sells under different brand names for under £40.
It is a really solid precisin tool unlike the red handled tool sold by CBS (also Sealey) it makes nice DIN flares.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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rusty nuts
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| posted on 29/3/15 at 10:22 AM |
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Franklin tools make a nice flaring tool which will make good flares on steel pipe so Kunifer etc is no problem , available for metric or imperial so
make sure you get the right one. I use one if I ever need to replace rusty pipe sections on the car using a joiner
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DW100
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| posted on 29/3/15 at 02:32 PM |
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quote:
I have read that one should NEVER use single flares on high pressure ie brake systems.
That'll be the issue then. Wrong type of flare.
Torque should be about 15nm not FT. Over tightening will cause the flare to be over compressed and end of the end of the tube nut will spread outwards
and be difficult to remove.
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