Leaking stainless brake line

[BigBlockOlds]

I have all stainless brake lines that I mocked up and had professionally bent and flared.
I've finally installed of my brake parts on the car and bench bled the M/C and installed it. I haven't bled the brake system yet since I have a hydroboost system and can't until the engine is up and running.
But, gravity so far seems to be doing a pretty good job getting the fluid through the lines because I came out to the barn this morning and found a couple of small puddles at the rear of the car.

I didn't have the fittings tightened like I thought so I snugged all of them down, wiped everything up and let them be for a while. Come back and two of the fittings at the 'T' block on the rear end seemed to seal just fine. But my drivers side line is still leaking between the fitting and brake line. This is on the end that connects to the rubber caliper hose.



I've loosened and tightened it down a few times but its still leaking. Are there any other methods I could try to stop the leaking? I took the line off completely to check the flares and they don't appear to be bad. I was going to try to reinstall it and make sure I get the line centered perfectly in the fitting before tightening it down.

Thanks for the help,

[parsonsj]

Andrew,

I've been lucky, and never had any problems with my flares leaking, but I've heard good things about this product:

http://www.purechoicemotorsports.com...rod/prd187.htm

jp

[BigBlockOlds]

I wonder if they make those in a 45* flare design?

I had a feeling that's why all of my other fittings haven't been leaking (fingers crossed). My proportioning valve and adjustable proportioning valve both have brass fittings which are probably conforming some to the stainless I would imagine.
I guess I could find a brass adapter for that location that might help?

[JRouche]

45 degree?? I thought all the brake lines were 37* JIC or AN???

Anyway. Are you using a flare wrench?? If not get one and REALLY lean into it. Thats why they make the wrench for the fittings. You really need to put alot of pressure on the nut, specially with stainless that doesnt want to conform to the fitting as easily as standard brake line. And I use a lil brake fluid on the threads if its a bone dry system to help the dry bite of dry threads. If the flare is a lil short it will leak, even with a gorilla tightening. JR

[BigBlockOlds]

To my knowledge, GM never used the 37* flare on anything stock. I know all of the brake lines on my car use the 45* flare which is much more common.

I am using a line wrench to tighten these down. Thanks for the tip with the brake fluid on the threads, I'll give that a try as well.

[JRouche]

To my knowledge, GM never used the 37* flare on anything stock. I know all of the brake lines on my car use the 45* flare which is much more common.

And yer right again. Durrr. Ive been working on my car and dealing with 37* so I forgot the double flare is 45*.. Solly JR

[parsonsj]

Sorry Andrew, I thought you were using AN flares.

jp

[Apogee]

Andrew, there are copper conical crush washers that would probably fix your leaks without risking overtightening your fittings...I've got a baggy of them around here somewhere. Give me a call or drop me an email if you're interested.

Tobin
KORE3

[E.rodz]

stainless can realy be a bear somtimes. if you use a tubing cutter this will harden the line and make it brittle to flare i would be willing to bet that your lines have a tiny little crack in them no matter how hard you tighten them they will still leak. try cutting the end off with a cut off disk on a grinder sand the end sq.debur the inside and flare again. hopfully you have enough line to do so. also before you tighten the line up spray a little wd 40 imbetween the flare nut and the tube this helps the nut slip on the tube while tighting. hope this helps.

[parsonsj]

if you use a tubing cutter this will harden the line and make it brittle to flare

Exactly right. Never use a tubing cutter with stainless: ss work hardens much faster than steel, and the combination of tubing cutter and flaring tool (especially double flare) can cause cracks.

jp

[BigBlockOlds]

Tobin, sent you an email about the copper conical washers. Are these fairly common that can be found just about anywhere? I've done a search online for the past hour and haven't found anything but the 37* conical washers.

John, from what I can tell the tubing wasn't cut using a tubing cutter. I had a Tubes 'n Hoses shop in Indianapolis bend and flare all of my lines since I didn't have the proper equipment. Looking at the left over tube they gave me back, it appears they used a cut-off wheel judging by the burr on the left over tubing.

Also, all of the brake and fuel lines I had made were aircraft grade seamless tubing. I had read somewhere that seamless tubing has less of a chance of leaking because it won't have a ridge in the flare where the weld would be.

Thanks guys,

[JRouche]

I've done a search online for the past hour and haven't found anything but the 37* conical washers.

Might be cause the only folks that are having issues are the guys using AN flare (37*) fittings and stainless line. OEM uses 45* double flare (as you reminded me), with some really soft line (compared to stainless line) and the leaking issue doesnt pop up. So no need for a copper seal.

And really, for brake line I personally dont see a reason to go to stainless. The good OEM line you can buy for next to nuthing is engineered to stand up to ALL the hazards of the road. Track or street. And its SO much easier to work with. You can actually force a tubing end that isnt perfect into sealing do to the softness of the OEM line. Not so with stainless. It wont flow into the flare, hence the copper washer seal for 37* lines in stainless..

OEM lines have copper in them, makes them malleable.. Im thinking with a stainless line you really have to have the flare right on the money, if not, cut off and re-flare. JR

[gearheads78]

I had the same problem with mine. It was cured by tightening and loosening about 10 times at each fitting.

[GetMore]

Not sure if it'll help, but I've heard of using anti-sieze on the threads and inside the nut to reduce the friction when seating the nut, to help force the flare to conform.
I understand that it is harder to get stainless to seat, since it is a harder material than normal steel line.

[Vegas69]

I recently changed my rear end configuration to some short hoses to make the brakes servicable without opening the system. I had leaks on both sides at the adapter. I found that the fitting threads hadn't been cut quite far enough and it was bottoming out just before it was seated fully. I took a die and about one turn was all it took. Also loosening and retightening will fix it sometimes as well. Once you think you have all the leaks fixed, you want to put constant pressure on the brake pedal for 2-3 minutes and it should stay firm. Then run your finger over every connection. They better be dry as a bone.

[ProTouring442]

I've seen those damned little washers a dozen times, but for the life of me I cannot remember where! Argh!

Shiny Side Up!
Bill

[ProTouring442]

OK, I've found some!

http://andersonmetalscorpinc.thomasn...r-flare-gasket

On another site it says they are rated at 2000psi working pressure, and 5,000psi burst pressure, though exactly how you could overpressure the washer when it is buried in the fitting, I do not know.

Shiny Side Up!
Bill

[Apogee]

Andrew, you should receive a few of the SAE inverted flare copper crush washers later this week some time, so hopefully that takes care of the leaks for you. I wouldn't call them all that common as I've never seen them before at any regular auto parts stores. I had to actively go out looking for them, and even then it took some looking. The ones we carry look just like the ones that Bill linked to above at Anderson Metal Corp.

Stainless is certainly less forgiving than steel bundy tubing, especially when using steel hose fittings instead of brass.

Tobin
KORE3

[parsonsj]

On my system, all my stainless flares are mated to aluminum -- except for the two connections to the rear calipers, and the ones coming off the master. I think the aluminum (like brass) is more forgiving on the mating surface.

jp

[BigBlockOlds]

Well, it looks like the copper conical washers Tobin sent me are going to do the trick! Thanks Tobin!!!

I'm going to let it sit for a while and then double check but I did start bleeding the brakes using a hand vacuum pump and now its at least able to pump up to 25" of vacuum. Before I couldn't keep it above 5 or 10 due to the leak.

Of course as soon as I sealed up the leak at the drivers side rear caliper, the passenger side started leaking. :( So I threw a washer on it and now it seems fine as well.

As you guys mentioned, I think its just the fact that at these two locations, I'm going from stainless to steel connections. Most of my other connections are stainless to brass and they seem to be fine.

Hopefully everything stays this way and I can mark the brakes off the list.

Thanks again guys!