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Old 21st June 2020, 16:06   #1
edwardmk
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Default Question on 190 rear flex to rigid brake union.

Been trying to release this union. My learning curve started with thorough cleaning, WD40, Ferrosol, Plusgas, and finally De-block oil. 11mm flare nut spanner too large, 10mm too small. Tried a few other spanners and found a 7/16 crowfoot on a ratchet fitted best, but the Hallelujah moment was short when I noticed the flare nut was turning the brake pipe. Custom cut a plumber's insulating mat, bit of tentative hot and cold ( possibly too tentative since I'm being v. cautious), but flare nut still is seized on the pipe.
So my idea was that if the flare nut was stuck, why not just rotate the flexible hose out instead? With care not to crush, I put a mole wrench on the metal collar of the flexi pipe ( due for replacing anyway ). It rotates easily, but only about 1mm either way and then seems to lock. What is stopping the rotation of the flexi-pipe or should I be able to turn it now the connection is released ?
Still trying to avoid brake pipe renewal as the rigid brake pipe is fairly new and looks OK. New respect for those who earn a living working on brakes
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Old 21st June 2020, 16:22   #2
David Lawrence
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Quote:
Originally Posted by edwardmk View Post
Been trying to release this union. My learning curve started with thorough cleaning, WD40, Ferrosol, Plusgas, and finally De-block oil. 11mm flare nut spanner too large, 10mm too small. Tried a few other spanners and found a 7/16 crowfoot on a ratchet fitted best, but the Hallelujah moment was short when I noticed the flare nut was turning the brake pipe. Custom cut a plumber's insulating mat, bit of tentative hot and cold ( possibly too tentative since I'm being v. cautious), but flare nut still is seized on the pipe.
So my idea was that if the flare nut was stuck, why not just rotate the flexible hose out instead? With care not to crush, I put a mole wrench on the metal collar of the flexi pipe ( due for replacing anyway ). It rotates easily, but only about 1mm either way and then seems to lock. What is stopping the rotation of the flexi-pipe or should I be able to turn it now the connection is released ?
Still trying to avoid brake pipe renewal as the rigid brake pipe is fairly new and looks OK. New respect for those who earn a living working on brakes

The flexi is locked in to a star shaped keyed hole in the bracket if you mean the end by the rigid pipe.

It might turn a very small bit then stop, but shouldnt really turn at all.

Depending on what job you are trying to do, if it is removing the caliper, i usually manage to unscrew the flexi from the caliper by swivelling the caliper around once its unbolted from the carrier
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Old 21st June 2020, 16:35   #3
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The flexi is locked in to a star shaped keyed hole in the bracket if you mean the end by the rigid pipe.

It might turn a very small bit then stop, but shouldnt really turn at all.

Depending on what job you are trying to do, if it is removing the caliper, i usually manage to unscrew the flexi from the caliper by swivelling the caliper around once its unbolted from the carrier
Thanks David. I suspected that something was stopping my simple solution lol. There is play because the union is loosened. I want to replace the flexi hose so it has to come off, but I'm trying to avoid damaging the flare nut and rigid pipe on the other end.
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Old 21st June 2020, 16:53   #4
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Thanks David. I suspected that something was stopping my simple solution lol. There is play because the union is loosened. I want to replace the flexi hose so it has to come off, but I'm trying to avoid damaging the flare nut and rigid pipe on the other end.
Slacken the flare nut by 1/4 turn, then tap the face of the union with a parallel drift, and tighten, repeat a couple of times, but if the pipe is truly seized inside the tube of the flare nut, then it's time for a new pipe




The serrated flange is what prevents the hose rotating
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Old 21st June 2020, 19:23   #5
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Slacken the flare nut by 1/4 turn, then tap the face of the union with a parallel drift, and tighten, repeat a couple of times, but if the pipe is truly seized inside the tube of the flare nut, then it's time for a new pipe




The serrated flange is what prevents the hose rotating
That's a really useful pic and I'll try the parallel drift. I'm guessing the serrated flange means no need for two spanners on the assembly line. Now I understand why no nut is needed to tighten the flexi from that pic. It's only the serrated section stopping me from rotating the flexi pipe out. If the parallel drifting fails me, as a last resort, could I section the spring piece ( I have the new ones you suggested on another thread ) to give enough space to disengage the serrated flange and rotate out? My replacement flexi pipe is a Wezmoto, but it has a nut and no serrated flange to complicate re-fitting. Your pic also looks like a really nicely made pipe. If yours is OEM, then my old one is aftermarket or a different OEM design. Just thinking out loud.
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Old 21st June 2020, 19:59   #6
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Yes, you could snap the strongback clip then pull the flexi out of it's bracket and wind it off the flarenut, the problem comes when you come to reattach it to the new flexi..........as you need to get the flarenut free on the pipe to do that.

When I fit new rigid pipework, I always smear the pipe with coppaslip, then slide the flarenut up to the flare and work the stuff around so the inside of the flarenut is well coated.

This prevents any chance of what you are battling at the moment happening in the first place.

Best of luck

Brian
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Old 21st June 2020, 22:33   #7
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Many thanks for taking the time to reply so quickly. Plenty for me to try here tomorrow, starting with carefully drifting! Really helpful and much appreciated.


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