The Stovebolt Site Forums The Shop Area Driveline Brake line fittings leaking - 1940 half ton

I am just wondering if anybody else has had this problem. I have installed new brake parts from front to back. Shoes, wheel cylinders, master cylinder, hoses and brake lines. Everything came from The Filling Station except the brake line set. Ordered the stainless steel lines from Classic Parts of America, which where bent to near perfection. I did NOT install all of the brass connectors new, as after a thorough cleaning I couldn't see a reason to. When I came to bleeding the brakes nearly every flared fitting was leaking. I went back to each one and attempted to get a liiiiitttle more on them, but stopped at the point I felt I may strip the threads or round off the flare fitting. I have the flare nut wrenches which I feel is important, but my feeling is neither the flare nut wrenches nor the open end wrenches fit as snug as they should. Is it the after market manufacturing that is slightly undersized or just that fact that I do not have Snap On tools? I don't know. The leaks appear to be the flare not seating and not the threads leaking. I am hoping some one has had a similar issue and can provide a solution.

I had one connection that seeped a bit when I first tried. It stopped when I retightened it (I loosened and then retightened). The difference was that I used copper-nickel lines versus your stainless steel lines, which are harder. You might try loosening each one then retightening and see if that fixes it. The brass should deform enough to make a good seal.

But you do need to run out and buy a full set of Snap-On tools.

(No don't do that unless you're using offshore tools. Mine are either Craftsman or NAPA and fit fine.)

It's possible that the angle of the flare on the tubing doesn't match the angle of whatever you're attaching it to.

The type of wrench you're using has nothing to do with it.

The angle of the flare may be an issue but the line set was specifically for the 40 half ton application so I assumed they had that correct. SS being harder does make sense so I will try to loosen and retighten. Most of my tools are Craftsman as well, but it just seems the wrenches have more slack than they should to prevent rounding. I do love me a good set of Snap On, but sheeeeessssshhhhh they're expensive. I appreciate the tips from you folks.

About 15 ft lbs. Don't over-tighten or the flare will crack. Check to see if a metric wrench fits better. You never know what kind of crap you're getting nowadays.

Here is what I do for seating stainless steel lines to the brass fittings.

Make sure that the brass fitting seats are clean.
Install the brake line into the brass fitting and tighten it snug without the wrench slipping of the nut from overdoing it.
Back off the nut slightly, then snug it back up again and pay attention to where the wrench ends up once it is snug.
Do not remove the wrench as you tighten and loosen the nut.
You will notice as you tighten and loosen the nut numerous times, the wrench will end up further clockwise each time.
Once the wrench no longer moves the wrench further clockwise as the time before. you have completed formfitting the stainless steel flare to the brass fitting and you should have no leaks nor boogered up flare nuts.

Flaring stainless isn't always the easiest thing to do. Do you know if the person who flared your stainless is a certified automotive tubing flare engineer or the kid they hired last week, showed how to use the machine once, then left him unsupervised because stock was low and they have orders coming in? I don't think any of us do. So, inspect the flared ends for cracks, splits and proper flaring. Never assume because it was new, it was done correctly. Use all new all new connectors when possible. Those old connectors could have had 86 years of bouncing down the road subject to flexing, vibration, application of pressure then release and warped the cone causing a shape mismatch. You've already tightened them, then gave them a death grip. If they are still leaking, they are going to keep leaking.

I have found putting some grease or oil on the back side of the flare and on the threads of the nuts helps, stainless steel will be worse for galling up. A steel nut on stainless tubing will bad, but a stainless nut on stainless tube will really be bad. I have worked on stainless steel lines on Compressed Natural Gas buses for years, and without some type of lubricant on the threads, you about guarantied to galled them together.

The lines were purchased at Classic Parts but when they arrived the box was from Inline Tube. The tubing is SS and the flare nuts are brass. You all have provided me with a Mondays worth of trials to get started on. Thank you all.

DadsFirstPickup - Not sure if it's applicable to your line fitting and loose wrench fitting situation, but when I last replaced a couple of my brake lines (we fabricated them using tubing and new fittings), I found that the new fittings thread count/pitch were correct for my '51 existing parts, but the hex heads where metric and not standard inch measurement sized. I wonder if your tubing fittings succumbed to the same situation and are actually metric hex heads???

Ya know - I would have never suspected as much and likely would have argued against the need to try. But knowing your story Dan, these new line sets could very well be providing that same situation. I will also check that as I loosen and retighten all fittings.

That thing with US threads and metric hex bit me once. I bought some tailgate chains from a vendor for my truck project. The threads were 5/16 inch and the nuts should have been 1/2" hex, but were 12mm instead (1/2" hex is equivalent to 13mm.)

Well I believe I may have licked the leaking. What 52Carl said made a lot of sense to me so it was Lefty Lucy/Righty Tighty a few times. I took a caliper to the flare nuts and my wrenches and it appears the wrenches are 4-6 thousands oversized and one actually was sprung to be larger than that at the tips. Looks like Snap On may not be a bad idea for certain wrenches. 🤔 And I was mistaken when I said the flare fittings were brass. They were a nice shiny brass color but are metal. The magnet grabs right to them. Still struggling to get any pedal pressure but hope to win that too.

To get pedal pressure sooner, tighten the brake shoes tight enough to cause quite a bit of resistance in turning the wheels.
This will lessen the amount of fluid needed from the master cylinder to cause the brake shoes to contact the brake drum sooner.
Once you have an acceptable pedal, adjust the brakes to specs.

Ever so often, I take my Craftsman flare wrenches to the vise and close them back up checking with a good new nut. Yes, better wrenches are out there, but the old Craftsman keep on working with a little help every now and then. Another good option is a crows foot flare wrench, they have a lot of material around them and don't seem to spread like a wrench does. I use the 7/16" one I have all the time to break old fittings loose.

I will give that vise trick a try. I looked at the crow foot but opted to pass cuz they won’t fit in most places I am struggling with.

I have old Craftsman from the '90s so they're still USA made. Their flare wrenches were pretty good, but I found the Mac Tools ones to be the best and they were slightly cheaper than Snap-On. Then I retired from active auto mechanic duty, so I didn't need to upgrade for the couple times a decade level of service my Craftsman sees.

Sadly, both Craftsman and NAPA are now offshore tools. Craftsman says "Lifetime Warranty" however they will only warranty the identical part number-and guess what? They changed one digit of the part number on all their hand tools, even the ones that are obviously clones of older USA made ones. So they won't actually honor the lifetime warranty like Sears used to do. More epic private equity skinflintery.

Not necessarily true about the part number change. I recently had a 3/8 10mm socket that was getting a little worn. I contacted them thru their warranty website and was sent a replacement with no questions asked. And I still have both the USA made "V" socket and the new one, which is made in Taiwan (slightly better than China IMO.) Still has a lifetime warranty on it and looks like it'll work.
Both sockets have the same PN, although the new one on the right is slightly different, without the business end knurling to say it's metric.

My Craftsman are all old enough to be made in the USA also. I can’t recall how many ratchets I returned for new ones but eventually started just buying other brands. One was as bad as the last. My wrenches I still use and like. Just never had the Craftsman flare nut wrenches and now I am willing to cough up the extra for good ones after my experience on this project. I should say this is probably the most need I have ever had for those wrenches though. 😁

Happy to report we have brakes.

What was the solution to stop the leaks?

Carls procedure. Tighten, loosen and retighten until the wrench stops going any further. That’s where my poor wrenches dilemma was painful.

I would like to add one more thing to this thread addressing the bleeding process. Adjusting the shoes to almost stopping the drums is excellent advise and there is no substitute for the old fashioned two man show of a pedal pumper and a bleeder valve person. I bought the vacuum pump and canister kit since I was alone. Bled and bled and bled to no avail. Got a pedal pumper in the cab and quickly had pressure. New gadgets aren’t always the best. Was that 2 things?