Is there a trick to tightening the brake line flare fittings and not leak?

I bought a new #4 brake tube (47314-04150) and it keeps weeping no matter how tight I crank it down. It weeps at the connection at both the frame and brake hose. I cranked it so hard that the flare nuts are almost rounded at the corners even with the holy grail Snap On flare nut wrench. I bought another new #4 brake tube to try again. I wanted to get some advice before trying again.

 

Alignment helps.
I try to make sure the flares are aligned evenly.
I finger tight, wiggle the line to make sure it’s aligned, 1/4 turn on the nut, wiggle, and then crank it down.

 

make sure you are lined up square, tighten it, then loosen and tighten again. Then do it again, tightening a little more every time.
here is an old timers trick with a copper flare gasket, you can find the video on YouTube


these gaskets are hard to find locally anymore, shop around for price, here is an example

$35 Parker 2GF-3-pk20 45 Degree Fitting, Flare, Brass, Flare Gasket, 3/16" (Pack of 20)

https://www.amazon.com/Parker-Degree-Fitting-Flare-Gasket/dp/B075F8P4ZN?th=1

 

I just went through this on my 1937 Chevrolet pick up project. According to in-line tube, you need to keep loosening and tightening down again repeatedly until the weeping stops. Trust me, it will stop eventually. You just have to get the swear words in the proper order for it to work out, right

 

If you tightened it that tight and it wasn't seated/aligned you probably already damaged the flare and it may never seal.

What do the seats look like?

 

I loosened the brackets that hold the brake hose so the brake tube would align and center when tightened but still weeped.

However I tightened it some more yesterday as a last ditch effort before changing the brake tube again.I checked again today and no more weeping.

I still have to change the brake tube on the driver side and I don’t want to run into the same problem as the passenger side. Is there some kind of guideline how many turns to tighten after finger tightening the flare nuts? I must have deformed the flare on then passenger side so it required extra tightening.

 

There is a torque, yes.
However, when I removed my rear axle, my line leaked.
And I thought I got it “tight”. I had to get it “really” tight to stop leaking.
I think the torque spec on the rear line was 11 ft/lbs or something?

Mine is definitely tighter than that……

 

maybe I should use a crow’s foot wrench like this with a torque wrench?

 

You could. I never used a torque wrench on a brake line.

 

I’m going to experiment with a torque wrench since the 10mm crowfoot wrench is not terribly expensive. I’ll try 11 ft/lbs first

 

The main thing is the line needs to be aligned/seated before you tighten the flare nuts.

 

Make sure the threads are clean, not cross threaded, and seat intact.
Ensure lines are correct mm size and pitch. Look at corrosion on threads/pitting/roughness and clean.
Some new lines/calipers/wheel cylinders threading may be slightly off/burred.
As already stated above hard lines are often difficult to begin threading straight on and that is where many fail - align/line up then jiggle/shake to start.
If they do not feel right remove and begin again. If threads really messed up replace and try again. More muscle should not be your first response to the leak.
Wire brush and brake cleaner can help clean threads. As brake fluid is dripping out it's hard to back off and try again I know - been there too. I keep rubber caps and plugs around to lessen that on brake jobs now.

 

Just throwing this in for future reference (and for me)

https://www.jalopyjournal.com/forum...tive-flared-fitting-leak-for-20-cents.128479/

https://koultools.com/fix-leaky-brake-line-fittings/

https://www.hoseandfittings.com/tag/leaking-flare-joints/

 

I spoke too soon. The new hard line stopped leaking at the connection to brake hose. Now it’s leaking at the hard brake line to connector block on the frame. I tightened it so much now that the threads on the connector block are damaged and I need a new one. It’s frustrating because I keep replacing components up the chain. It’s a very slow seepage that doesn’t show up right away.

At this rate I will probably replace everything leading up to the master cylinder.

 

These work great - in industrial settings a lot of people use these by default - not AFTER a joint leak. It saves a lot of grief and aggravation and having to redo the joint to begin with.

If you have a Grainger nearby, it's easily ordered for pickup - if it's not in stock, it usually comes in within 2 days. You don't have to be a "commercial" customer to buy from them anymore. I don't know how the price is compared to Amazon though.

 

I thinking of trying this but I thought they are trying to remove copper parts in the brake system.

 

The only place I'm aware of as far as any effort to remove copper is in brake pads. Copper is frequently used in NiCopp brake lines (Cunifer being another brand).

I found the Grainger page (if you have one near) - way cheaper than the Amazon price.

https://www.grainger.com/product/PA...me-_-Purchased_Products-_-HPMPPZ&cm_vc=HPMPPZ

 

It's possible that you might be over tightening it.

 

I just bought a new frame connector (90 degree metal elbow) and hard line to try again. I want to try again without the flare washer. Then try the flare washer if the new parts still leak

Do I finger tight then another 1/8 turn as a starting point?

 

I believe the spec is 11 ft lbs. I don't know what that translates to in a rotational turn. SEEMS like 1/8 of a turn would be way below that.