struggling with stainless line leak - Team Camaro Tech
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post #1 of 13 (permalink) Old Oct 3rd, 01, 05:43 PM Thread Starter
mwh
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Marc
 
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For my ground up resto, I replaced all brake lines with stainless steel lines. All of the lines except for the one going into to the prop. valve under the driver's door are leak-free. For some reason I cannot get this one to stop leaking. The flare looks okay, the seat in the valve looks okay. I even tried repeatedly loosening and tightening the fitting thinking that it would help seat the flare. It still leaks. Does anyone have any suggestions to get this sucker to stop leaking? I thought I remember reading somewhere that roughing up the flare with a little sandpaper might help it seal?

Thanks,
Marc
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post #2 of 13 (permalink) Old Oct 3rd, 01, 06:04 PM
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Try giving Earls a call and ask for a conical seal for the line size that is leaking. The hardness of the stainless, bad flares, non-seamless tubing, etc. can cause the connection to leak. The conical seal is a small brass insert that goes between the line and seat and will conform the tube irregularities.

You may also want to try http://www.bakerprecision.com

Though it's not the preferred way to do it I have cleaned up stainless tube flares by using either a 37* or 45* countersink, but care must be exercised on brake lines. On brakes the conical seal is a better option.


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[This message has been edited by CarlC (edited 10-03-2001).]
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post #3 of 13 (permalink) Old Oct 3rd, 01, 07:10 PM Thread Starter
mwh
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Marc
 
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Thanks for the quick reply! I see that these conical seals come in sizes: 3,4,6,8,10,12,16. Any idea what size I need to get for my brake line?

Thanks,
Marc
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post #4 of 13 (permalink) Old Oct 4th, 01, 03:40 AM
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Carl
 
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Measure the outside diameter of the tube. It should correspond to what's called the "dash" number. -3 = 3/16", -4 = 4/16", etc.

Brake systems usually use a 45* SAE flare. Verify that the line and conical seal have the same flare angle. SAE = 45*, AN = 37*.

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post #5 of 13 (permalink) Old Oct 4th, 01, 05:26 AM Thread Starter
mwh
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Marc
 
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Thank you very much! I'll get the line measured and get some seals ordered. I hope this does the trick.

-Marc
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post #6 of 13 (permalink) Old Oct 4th, 01, 04:56 PM Thread Starter
mwh
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Marc
 
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Well, I think I found the cause of the leak. Looks like some moron (me) overtightened the flare onto the seat when the tube was slightly off-center. It cut into the flare and damaged it. There goes another $75 for new lines.

-Marc
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post #7 of 13 (permalink) Old Oct 4th, 01, 05:52 PM
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Mabye you can get the end re flared?
David

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post #8 of 13 (permalink) Old Oct 4th, 01, 07:02 PM
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I agree with David. If you don't have a flaring tool remove the line and take it to a hydraulic shop. Have them re-flare but keep as much of the length as possible.

Join the rest of us morons!

I'm a moron too!

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[This message has been edited by CarlC (edited 10-04-2001).]
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post #9 of 13 (permalink) Old Oct 5th, 01, 06:59 AM Thread Starter
mwh
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Marc
 
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Should I do an SAE 45* or an AN 37.5* flare? I've read conflicting viewpoints for stainless tubing.

Thanks,
Marc
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post #10 of 13 (permalink) Old Oct 5th, 01, 08:49 AM
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I read somewhere that for stainless you should use a 37.5* flare due to the higher possibility of cracking the stainless line. Do not know what truth there is to that however.

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post #11 of 13 (permalink) Old Oct 5th, 01, 03:08 PM
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If screwing into standard automotive components, they are 45 degree, so the lines must be 45 degree too.
Aircraft and race car fittings are 37 degree.
The 37 degree provides better sealing with lower nut torque when using aluminum aircraft fittings. I believe there is a half degree difference between male and female 37 degree fittings for a better seal.

I don't remember reading about stainles lines cracking because of 45 degree flairing. But a 45 steel line flare MUST be double flared for brake use, a 37 degree brake line can be single flared and a backup collar used to reinforce it. So I guess it's true the 45 degree is more likely to crack -if single flared.
David

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post #12 of 13 (permalink) Old Oct 5th, 01, 03:09 PM
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You can either measure the angle or use another fitting to determine the angle. If you seat a fitting into the flare and a line contact occurs then the angles are not compatible. If a large contact area shows then you are good to go.

You must use the correct flare angle regardless of materials.

Stainless only requires a single flare. It is too hard and can crack if a double flare is used.

Aluminum requires a double flare for -6 and smaller.

If your brake line is stainless go single flare. If it's mild steel it must be a double flare.

Carroll Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook is a handy book to have around.

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post #13 of 13 (permalink) Old Oct 29th, 01, 06:18 AM
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CarlC,

All of the stainless brake lines I have seen are double flared. I just installed a new front-to-rear line on my car.

Also, I had a problem a while back finding someone in Dallas that could double flare a stainless line. Because stainless is much harder, most shops said their equipment couldn't do it. The only place I could find was an aerospace hose shop and they only did AN spec flaring. I would up getting a new line.
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