MG Sports Cars

Wiring went well... not finished, but easily would have been if I hadn't switched to working on the brakes.

A friend came over to help so while I had the 2nd set of hands (or feet in this case), we decided to fill & bleed the brakes. Since I didn't have any leaks when I did the clutch, I was expecting good things. Well, probably 1/2 of my brake fittings leak. About the time we'd get one to stop, another one would start leaking. Very frustrating. I was confident the leaks were from the flares I'd made so I replaced a couple lines with pre-flared lines -- they were longer than needed so I had to put some extra bends in them but at least the factory flares wouldn't leak -- or so I thought. Some of those leak too. I even put a new T in on one thinking the flared part in there was damaged (brass T/steel lines) but still leaked. The only good news is neither of the bubble flares I made for the brake master leak. And, none of the AN fittings leak. It's only the 45* inverted flares that leak -- of course, there are a bunch of those!

Not sure what to do at this point so going to finish up some other stuff & make some calls to see if there's a local shop that will do the brake lines for me w/o breaking the bank.

Other suggestions welcome.

Rob

Rob,

It takes a better mechanic than me to replace all the brake lines on a restoration. I've tried it several times and the leaks I create can never be fixed - without a guy who knows his stuff. Then he just has to almost start all over again to fix my mistakes.

Good luck in finding such a mechanic ! He is worth his weight in gold and may bill you accordingly.

Wishing you much luck with the most difficult part of a rebuilding project.

Keep them on the track

phillip g

Rob, bad news but I'm sure you can fix it. Just a thought, did you use new flare nuts with the new lines or reuse the nuts from the old MG lines? The flare nuts for bubble flares will not support a 45 degree flare properly and vice versa the nut has to match the type of flare. Second the 45 degree flares have to be double flared or the flange won't be thick enough to be properly seated by the backing nut. I figure you probably already knew this stuff, but just in case it was all I could come up with since the bubble flares you made sealed fine.

Good ideas Bill. Used new flare nuts for 45* inverted. I got all the brake line from the local AutoZone -- it has a dark green epoxy or powder coat finish on it. One of the pieces I remade was plain steel & it seems to be holding. I'm beginning to wonder if the line (or combination of the line & flaring tool I have) are what's causing the problem. I think I'm going to get another piece of the plain, unfinished steel line replace another section & see if it holds... But, I think I'm going to finish everything else first.

Rob, the first Bucket I plumbed leaked so bad I kept pie pans under the connections. I flared and re-flared, practiced and did it again. The brakes will punish you until they feel you've suffered enough and then by some stroke of luck they will give you a break, pun intended. After fabricating brakes on a number of these things and making countless double flares I still have no idea what the secret is, but my bucket has been on the road for five years now and hasn't dripped a drop since. I haven't plumbed my GT yet and to be truthful I'm not looking forward to it because I know I'll spend some sleepless nights before it thinks I've suffered enough. I'm pretty sure it’s all done with mirrors or maybe it's just plain magic.


Advice from me might not mean much, but DON'T skimp on a good flaring tool, particularly if you’re using pricey synthetic fluid. Get your hands on as good a one as you can and spend some time in front of a TV with scrap brake lines. After five years it's paid off but I still get a hemorrhage occasionally!!



Edited 1 time(s). Last edit at 06/21/2010 11:48PM by pspeaks.

Rob,
Like Paul said, a good flaring tool is important. I was using a sustandard tool on my project and had more leaks than I expected. All the leaks were corrected by further tightening of the connections. Obviously, there's a limit to how much you want to torque these down to, but keep in mind, you'll probably never disassemble them again and you want it done. What I'm trying to say is, are you sure you have all the culprits tight tight?
Ken

Rob,

I can only think of one other thing that hasn't been addressed:

When you tightened the nuts, how were you holding your mouth? Was your tongue stuck out the left side or the right? You know you have to hold your mouth right to get the proper torque on those lines.

; ) Looking forward to seeing you car in INDY!

Dan B

I've tightened quite a bit but will tighten some more to see if that helps -- can't get worse (I think there's a leak on at least one end of each section of pipe).

LOL Dan... all I can say is whatever way I was holding my mouth wasn't right. Tongue was moving along the lines of $*@& son of a $*#&@!

Rob, as I understood it you were having trouble with the British bubble flares? Those use a flare nut which has a section on the end with no threads, about 3/16" long. Take the nut before flaring and make sure it will turn by hand all the way in to the seat. Often the end of the nut itself gets flared out from over tightening and this will cause trouble so do this check every time. Then on the flare itself, prepare the end of the line carefully, removing any burrs and smoothing the end in order to get a clean, defect free bubble. Finally, make sure that the finished bubble has the hole properly centered and is symetrical, with no flat spots or bulges. Do all of that and it should seal properly. I've made many flares this way over the years and rarely have problems with leakage but the devil is in the details so take your time with it.

JB

Actually Jim, the bubble flares I made aren't leaking at all. There's only 2 of those (at the master cylinder). It's the 45* inverted flares that are leaking. I'm my flares aren't perfect because I had a T with 2 of the 3 ports leaking. After replacing the 2 leaking lines with new lines that had "factory" formed flares on them I still had leaks. Next step was to remove the T itself & inspect it -- sure enough the cones on the inside of the two ports that were leaking had been deformed (mashed down a bit part way down the cone). I replaced the T with a new one, but still have leaks -- don't know if the deformed T damaged the factory flares.

1st step will be to tighten even more. If that doesn't work, next step will be to replace both the T & the lines at the same time to see if that solves the problem. If that doesn't work I'll have to take it to someone who knows what they're doing!

Rob, I can't address bouble flares because I haven't done one. All I've done is inverted double flares and they take a bit of practice. Eventually you'll get where you can look at them and tell if they're going to work, well, a lot of the time anyway. Jim is right, sometime you just have to tighten them until your eyes cross, but you can tighten a really bad flare and it won't help, still, try anyway, what have you got to lose!. Probably everyone on this site has been through this, some more than once, and will tell you to keep your head up, it will get better.


"P"

Instead of just tightening them more, back them off and then retighten. Do this a few times for each fitting and see if it helps.

Steve

I must be doing something right because my Harbor Freight flaring tool has made many leak proof flares over the last few years. In fact, I just made several lines for a "C" and none leaked. There are a couple of tricks I use to ensure a good flare.
1) I found that use of a secondary C-clamp near the work to keep the clamp halves from spreading during the flaring process.
is required
2) To Jims point, the end has to be flat and burr free and then I found that lubrication of the bubble flaring tool helps keep the flare even/centered - if the tool/tube is dry during the flare forming process, I found the incidence of poor flares much higher .

Graham, though our flaring tool is a MAC, we too use a lot of Harbor Freight stuff. I didn’t think to suggest it but we do exactly as you described and get about the same percentage of pass/fail flares. The distance the tube protrudes from the face of the tool is also important. "P"

I guess I've been lucky over the years, never had any leaks, but I've had to redo some flares that cracked in the tool etc. I was lucky enough to be taught how to flare lines by the mechanics in my dad's dealership back in the 60s. As Paul says the distance the tube protrudes from the flaring tool clamp is critical. Here's a link to a pretty good description of the process with a good photo of that measurment. [www.carcraft.com]
One tip I was given as a kid was to lubricate the end of the tube by dipping it in some brake fluid. That acts as just enough of a lubricant and won't contaminate the lines in any way either.

Coated gree fittings are metric, brass color or adonize brass color are standard flare whic is 45 degree.
AN flare is 37 degree. Also some green color fittings have a shoulder in them and will never seat correctly unless you have the proper recieving end.

Overtighten double flare (45's) will distord the flare thus making it leak during bleeding or when you apply heavy pedal force to stop. It is a safety issue.

Tighten correct fitting until it seats and turn about 1/8" that should be enough to make it seat properly.

Bill, YOU SAID IT, as an airplane guy I should have thought to mention that, but didn't; My Bad! "P"

Ed,
You're using flare nut wrenches right? If not that could be part of the problem.

Abbreviated from Wikipedia; Flare-nut wrench - it has a narrow opening just wide enough to allow the wrench to fit over the tube. This allows for maximum contact on plumbing nuts, which are typically softer metals and therefore more prone to damage from open-ended wrenches.

Standard open end wrenches can distort the fittings when you tighten them and the distortion can get worse it you over tighten trying to stop the leak.

I feel you pain. I connected my clutch hydraulic lines and got the clutch working but have two leaks. One where two purchased fittings connect and one at the flexible hose connection at the slave. The double flare I made at the master cylinder does not leak. Go figure.


Steve

Good info Steve. I do have flare nut wrenches but didn't always use them. In some of the tight spaces, my smaller open ends were easier to use. I'm surprised a standard wrench would do more damage than rounding over the corners, but at this point I'm ready to try any & all tips when I'm able to get back to the brakes -- hoping that will be next weekend.