The Stovebolt Site Forums The Shop Area General Truck Talk Brakeline Frustration

Well I went and redid my whole brakeline over winter. I rebuilt all wheel cylinders and the master as well. All new flex lines, copper washers, and steel lines. I flared the lines myself to the point you can't tell a factory end from mine.

The front and rear flex lines do not leak at their junctions on either end. Unfortuneately, the problem is that all the original brass junction blocks leak (rear wheel blocks, diff. block, and m.c. block). It doesn't matter if I use the factory end or mine, or if I retighten. I was under the impression these could be reused. Is this not the case? Can you even find these blocks. I'm really quite frustrated with the time and money already spent on this. Or am I missing something?

Kyle

I was able to find brass blocks at Home Depot and/or Lowes...

I just redid my '51 GMC 1/2 ton completely about 2 months ago. The only parts I didn't replace in the hydraulics were those brass junction blocks (I couldn't find them either). When I tightened everything up and put fluid in it, the blocks all leaked. Oh yeah, I used preformed brake lines that were made for my truck.

After doing some research, I realized that I was using the wrong type of wrench to tighten the brake line fittings. If you don't have one, you need a flare wrench. I got one from NAPA with a 3/8" on one end and a 7/16" on the other for about $10. What a difference! The attaching nuts I thought I had tight were not. The flare wrench reaches nearly all the way around the nuts and gives you better leverage. After retightening everything, I got it down to a few leaks. I kept working with them and now my brakes are tight and leak-free.

BTW I did new (repro) Master cylinder, wheel cylinders, brake lines and flex hoses. Had about $400 in all the parts.

Good luck with it,

David Bush

An automotive inverted flare hydraulic system is actually a one shot deal. It's not designed to take apart and re-use. A properly formed double flare on a steel tube should not be crushed completely flat as many people do with the clamp type flaring tools. The double flare should have a little give or crush left in it until it is tighten down in its final resting place. That way it conforms to the shape of the inverted flare in the brass fitting. At the same time the inverted flare in the brass fitting gets crushed a little bit also since it is softer then the steel line. After the joint is tight you have a unique matched seat until you disturb it. When you break the joint and try to reseat it, sometimes if you luck out there is still enough give in the brass inverted flare to form a seal but quite often there is not and you will have a leak.

When you break a hydraulic brake line open you create a domino effect which ends only when you terminate at a pipe thread or a flat seal with a copper washer. (Those copper washers are also a one shot deal unless you anneal them and remove the grooves.) In other words, you are way ahead of the game if you replace all the fittings and start with fresh double flared tubing.

With the steel line into the steel master cylinder your can usually get away with a couple shots before the line is crushed so much that it will not conform to the inverted flare in the master cylinder. This is also true in the case of the bleeders, after numerous bleeding sessions the bleeder screw will become work hardened and your better off replacing then, they are quite inexpensive.

Denny Graham
Sandwich, IL

Denny, Excellent advice!

I understand what Denny is saying but if you took a survey here, I think you would find that the majority of Bolters here replaced the brakelines without replacing the blocks. One of the critical things in getting a leak free joint is to make sure that the line is straight on before threading the fitting. The fittings are very unforgiving if this isn't the case.

I'm not going any further than to say this Fred, but I'll bet that the majority of the Bolters here, that didn't replace the brass had trouble with leaks somewhere down the line. Like I said, you can get away with it sometimes, but to be 100% sure you have a solid leak-free system I'd just bite the bullet and start from scratch. Using the old brass or lines is just a coin toss. Once you have a new system in place there is no reason to break into it for 100,000 plus miles, which in most cases is the life of the vehicle.

And of course at if you have to change a wheel or master cylinder the first or second time you will probably get away with using the old line. And I repeat, steel to cast iron you can some times get away with a couple of times before the tubing work hardens and will not conform to the seat. Your local Midas and repair shops and Sunday mechanics change cylinders all the time with out changing the line, me included. And it’s with the hope it goes out the door without leaving a trail behind or until the 90 day warrantee is up. If the line has to be changed then the domino effect enters the picture.
Mind you now, it’s a hobby for me, not a way to make a living and this is just my opinion and the way I do my work. So I be done with this subject for now, no argument from me, if you don’t like my way then quite simply, do it your way!
Denny Graham
Sandwich, IL

Sometimes you can flare the line and not run the flare tool all the way in so you have some crush room when it goes in the brass block. Also, grease the back side of the flare and the tube around it so you tighten it with out binding or twisting.

Joe

You should be able to look inside the brass block and see the angled seat that the brake line tightens against. If you see any distortion at all then then you have found the problem. Also push the nut all the way against the flare and make sure that the threads on the nut are square with the actual flare on the end of the steel line. As mentioned above, tighter isn't always the deal. If you have distortion your going to have a leak and usually if you clean everything up good and get out a magnifying glass you should be able to see why its leaking.

Thanks for the advice. I'll search for some new blocks and a better wrench. I might a have enough slack in the lines to creates some new flared ends as well.


Kyle

No offense, Joe H, but I wouldn't grease any of the brake fittings anywhere. The grease can contaminate your brake system. It's the same as putting wheel cylinders together: use only brake fluid as a lubricant.

David B

Well I would agree with ya about not greasing the flare nuts Dave, and, no offense, but I would disagree wit ya on not using any grease. I've been greasing the adjusting threads, links, a dab on the contact points of the springs and a wipe at the shoe-bearing surfaces on the backing plate. Oh yes, and the parking brake links also get a dollop of Lubriplate.
Been doin’ it this way for better than a half century and never had a come back or complaint.
Denny Graham
Sandwich, IL

No problem David. I like a little grease on the threads and back side only of the flares, I use a silicone grease made for brake assembly, much like Denny pointed out. Most of the time they go right in with out any problem, but the ones that do leak, the grease lets me get them just a bit tighter and most of the time seal them.

Thats what so good about this site, you can get four or five different ideas for the same problem. Joe

David is right. A set of tubing wrenches is a very good investment. They save a lot fittings from being rounded off

I respectfully disagree with Denny. I've run and replaced lines on a lot of vintage vehicles, and have written several tech articles on the subject, plus talked with most or all of the industry suppliers for repro brake and fuel lines: Master Power Brakes, Inline Tube, Classic Tube, Stainless Steel Brakes Corp, Baer, etc.

The brass fittings ARE reusable. The tube flare seats down on the nipple inside the brass fitting, and laps onto it. That is where the seal is made. Steel is much harder than brass, and if you don't make the flared end on the steel completely flat with the flaring tool, you will destroy the nipple inside the brass fitting, as it will collapse or deform from the force of the steel tubing. The brass nipple will NOT deform or move the steel.

I have gotten the odd brass fitting that has the nipple crushed--they're junk at that point, and won't make a good seal.

A lot, if not most, of the brass fittings are unique to specific applications: for instance, the junction block on top of the rear end housing. Your local parts store isn't going to have that one. A lot of fittings are also manufactured with some sort of provision for securing the fitting to the chassis, with either a tab for a bolt, or grooves for a clip (such as the front line fittings, where the hard line goes into a tab welded to the frame, and the rubber line to the wheel goes in from the other side). When I go to junk yards, I like to grab a couple of these kinds of fittings from different vintage vehicles--they come in handy. 90-degree and T-fittings particularly.

It's not uncommon at all to have leaking fittings after a complete rebuild. The fix is very simple: rather than crank down the union and tighten the beejeezus out of it, instead back off the nut and snug it up, repeating three or four times, then firm it up and call it done. This will seat the flare on the brass nipple, lapping it in. I've had your same problem time and time again, and this fix has worked nearly every time. I learned it from one of the brake line companies, and have used it on my '54 Buick, '62 Suburban, two Dodge Dakotas, and the brakes on my dad's boat trailer. Before I learned that tip, I cranked 'em down like you are.

If that doesn't fix the leaks, take it apart and look at the nipple inside the brass--if it's crushed, distorted or has a huge gall across it, you'll need a new fitting. I've seen one completely crushed, and another with a huge gash across it like a piece of debris was smashed in it.

This months' issue of Hot Rod Deluxe magazine has a story on bending and flaring your own lines.

-Brad

Ok, my view on this topic: I agree most with Brad on the brake line issue. I too, have replaced many brake lines and cylinders without trouble, and have made many double flares on steel lines. My experience with double flares is that the first dozen or so should be for practice, then go cautiously with some for 'real.' Also, with double flares, if you get a bad one, you have to cut off about an inch of line before trying another- the steel line work-hardens, and if you just cut off the flare, the hardened line won't flare properly- although it might look alright. I didn't see any reference to the flare angle in this discussion, but the wrong tool will give the wrong angle, and after tightening the new flare, the flare seat will be distorted and unusable for anything.

In my opinion...

Harvester

I bought a good Snap-on flare kit 20 years ago when I was 17, and it's still offered by Snap-on, for only $130 (it was $97 when I bought it). Worth EVERY penny. I highly, highly HIGHLY recommend it. I have never made a bad flare on stainless or mild steel lines. I haven't had good luck with the new green coated "soft" lines in the parts stores these days.
Inline Tube offers a straightener that will take the curl out of coiled brake line (bought in a box). I've got one ordered.

Do NOT go with a cheap tubing cutter--they work harden the area more, and it's tough to get a square cut with them. I also have a set of cheap needle files I added to my kit, to deburr the newly cut ends.

All automotive fittings are a 45-degree double flare. NOT 37-degree flares, such as A/N fittings.

-Brad

Actually, that is not true. Most newer cars use the ISo Metric flare, more commonly know ans the "Bubble Flare". It kind of looks like a 1/2 finished 45 degree, but most definetly is not. while this doesn't really apply too much to our old 'Bolts, it can come up, especially to those among us that are using late model parts in the brake system. If the incorrect flare is used, the fitting will most definetly leak. so make sure that you properly ID the fitting that any doner parts use, late F-Body and S trucks are ones that can have the ISO type flare.
Anyone needing a good instruction on how to properly flare brake lines, check out my Webshots album. I beleive the Denny also has a demonstration in his, only using the Fed-Hill flaring tool instead of the Snap-On tool that I used.
I would also like to ention, I work prefessionally as a brake/alignment mechanic, and re-use the brass all the time. never had one leak, exept in cases where the threads were bunged up.

Longbox,
I had a look at your flaring pics in your album. That is a very nice set of flaring tools. It doesn't even resemble the cheap junk tool that I bought and discarded! For anyone wishing to look at the photos, they are on page four of the Longbox album.