Double flare fail?

[dlundblad]

I tried splicing an existing line to some new by making 2 double flares and using this union. I’m assuming this style union needs double and not bubble style flares.

The union sits vertical on the truck so it’s hard to tell if it’s just the top flare or both, but I’m getting leaks. I wonder where I went wrong. Perhaps I didn’t make things tight enough? The flares looked great.

 

[FowVay]

The packaging for your union specifically states "inverted flare" which is a double flare style. You seem to have the basics correct. Maybe it's just not tight enough.

Here's a cutaway picture from a youtube video that might help.

 

[PF52]

What are you using to flare the lines? I tend to think the slightest off-centerness (or something?) of the flare will make it prone to leaks.

Perhaps it is a function of the flaring tools I use, but I get about one double flare out of four that leaks. For that reason I only use bubble flares which have been 100% leak-free for me.

 

[atikovi]

Perhaps it is a function of the flaring tools I use, but I get about one double flare out of four that leaks.

^This. I had one of those $40 flaring tools and the results were mixed. Bit the bullet and bought the Mastercool hydraulic tool and they have been leak free the first time everytime.

 

[dlundblad]

What are you using to flare the lines? I tend to think the slightest off-centerness (or something?) of the flare will make it prone to leaks.

Perhaps it is a function of the flaring tools I use, but I get about one double flare out of four that leaks. For that reason I only use bubble flares which have been 100% leak-free for me.

I’m using the higher end kit from HF. Made in Taiwan so I figured decent quality.

 

[burbguy82]

A flare connection very reliable, assuming it was done properly.

Your question is hard to answer.

There can be a slight variance in "go " and "no go" when you are talking flares. I would tighten it supper tight and see if that works. If not, you did something wrong, or the part is bad.

Is this for brakes or what?

 

[dlundblad]

A flare connection very reliable, assuming it was done properly.

Your question is hard to answer.

There can be a slight variance in "go " and "no go" when you are talking flares. I would tighten it supper tight and see if that works. If not, you did something wrong, or the part is bad.

Is this for brakes or what?

Yes, it’s for a brake line.

 

[andyd]

I haven't repaired brake lines in several yrs. I found using care in preparing the line to be flared. The cut edge of the tubing needs to be filed off so that you have the full thickness of the tube to mold and it is flat. Just using a HF 30$ tool

 

[sloinker]

The exposed end of the tubing in cheaper hand flaring tools is critical Too short and you don't get an acceptable double end as intended. Too long and you will get microscopic/tiny fine cracks along the face of the second flare. I have stopped having these issues with the copper alloy brake tubing, seems more forgiving. Steel and stainless steel....not so much. Used tubing is the worst.

 

[dlundblad]

The exposed end of the tubing in cheaper hand flaring tools is critical Too short and you don't get an acceptable double end as intended. Too long and you will get microscopic/tiny fine cracks along the face of the second flare. I have stopped having these issues with the copper alloy brake tubing, seems more forgiving. Steel and stainless steel....not so much. Used tubing is the worst.

Makes sense. I bought ni copper for one side and it seems fine.

Splicing new to original seems to be the issue

 

[eljefino]

Why do you have a metric union? If you're doing regular 3/16" brake line use an SAE sized one. The Blu-9c is a 10x1mm.

Beware-- a 3/8"-24 line nut will fit into a 10x1mm coupler but can blow out under pressure. The threading is nearly the same.

 

[dlundblad]

Why do you have a metric union? If you're doing regular 3/16" brake line use an SAE sized one. The Blu-9c is a 10x1mm.

Beware-- a 3/8"-24 line nut will fit into a 10x1mm coupler but can blow out under pressure. The threading is nearly the same.

The union’s threads are metric, but it’s for a 3/16” line.