compression fittings on brake lines

I know here in Maryland compression fittings will fail on Maryland inspections. But I also have customers that use them too. As far as I know they haven't had any issues with them. I know I wouldn't want them on my car. I'll only use unions, or replace the whole line.

Chas

Proof that anyone can spew advice on the interwebs

Sadly, ehow doesn't seem to have a "-1" button. I'm guessing most intelligent people take anything posted there with a shaker of salt anyway, but really, this is astonishingly irresponsible.

nate

is there a publicly available document that explicitly states that compression fittings should fail a safety inspection? This is actually pertinent as the guy to whom I was talking is in MD but not an inspector and I'm sure he'd appreciate a correction if it saves him from potential future liability down the road.

nate

will you settle for proof (almost) by contradiction?;

indicates that SAE spec J2879 "applies to 90 degree double inverted flares used on common sizes of automotive hydraulic brake tubes, and their associated tube nuts and mating ports"

every test I've ever taken, had as the correct answer for brake line repair, "use a double flare".

and that's enough for me, GW

I don't know.

A quick web search shows this discussion in multiple venues with several comments such as 'will probably be OK' without direct experience and also 'will fail inspection' but no statute cited. Of course it may be an administrative policy rather than a statute. Or not.

Frankly I don't see any problem with a normal flared line which logically seems matched to a 'high stakes risk when it breaks' application. Flares and flaring tools are cheap, well supported, ubiquitous and not complex.

If any of my cars had dual-diagonal braking systems and if I were away from civilization (new brake line and/or a flaring tool), I _might_ think about a compression fitting. But they don't and so I don't.

I agree 100% with your position, problem is that I'm advocating your position but I can't find any official backup to it (at least in MD or VA; I have found explicit references for other farther away states) therefore I'll never change the guy's mind as to what is and isn't a proper repair as I don't really have any backup.

For my own part I will continue to flare...

BTW is it just me or has steel tubing gotten softer over the years? I had to do three different flares to make the repair, one under the vehicle (which always scares me, I prefer working on the bench) and they weren't nearly as much of a PITA as I remembered. I did deburr the lines and dress with a file before attempting to flare but I was doing that before as well. Been years since I've had to break out the flaring tool and I can't say that I really miss it, but it is awful handy to have (and it just looks more professional when your lines are the exact right length rather than having loops in them...)

nate

Maryland inspection regarding brakes.

Procedures: Reject Vehicle If: (a) Hydraulic System?Visually inspect condition of hydraulic system. (i) Inspect wheel cylinders for leakage and operation. Do not remove dust covers. (ii) Inspect hydraulic hoses and brake lines for leaks, cracks, chafing, flattened or restricted sections, improper support, rusting causing pitting, and improper material. (iii) Inspect master cylinder for leakage and fluid level of all sections. (Be sure no dirt gets into reservoir when cover is removed and that the gasket is serviceable.) (a) (i) Wheel cylinder leaks or fails to operate. (ii) Hoses, or brake lines are cracked, chafed, flattened, restricted, or are rusted and pitting is visible, are improperly supported, or lines have been repaired or replaced with copper tubing or other material not designed for hydraulic brake lines. Hoses or brake lines are mounted to contact wheels or body during steering or suspension movement. (iii) Master cylinder leaks. (iv) The fluid level in any section is less than 1/2 full. (v) The gasket does not properly seal master cylinder.

Compression fittings fall under the "material not designed for hydraulic brake lines"

Connecticut:

BRAKE LINES - Tubing must be steel and properly attached and supported (at least every 18") and hoses shall not be kinked, twisted, or frayed. Hoses must not be under tension during full right and full left-hand turn, or during full compression or full extension of suspension. Automotive stainless steel tubing and braided hoses are acceptable but compression fitting will not be allowed.

In NY they are specifically called out as an automatic fail if used on any part of the brake system as well.

The problem is that some states don't have anything in the requirements other than something general like "the brakes must stop the vehicle" REALLY??

I know a few states specifically call attention to compression fittings being bad juju.

Personally by the time you get the correct compression fitting size, get the line clean enough to seal and cut correctly, it it faster and easier to spool out some line and flare it.

I keep a good supply of line in steel, stainless and cunifer on hand. plus all the fittings and about 4 different flare tools.

Some folks even argue that adding the additional flare fittings in the line is too dangerous. I disagreed with this as I have found that flare fittings once they aren't leaking they'll never leak until someone attempts to take them apart and the line breaks because the fittings are rusted together.

In a pinch to get home yeah... just about anything goes under such conditions. If I had no flare tool and all I could get a hold of was plumbing materials... ok... that's desparation mode to hobble carefully home or to the nearest place where the proper materials could be purchased. For an actual long-term repair? no.

You can always ask the State Police

Understood, but it doesn't seem like MD or VA explicitly do so...

Agreed!

Thread drift: what flaring tool do you use on 3/16" stainless tubing? I would love to be able to fab my own stainless lines but the instructions for my best flaring tool (K-D I think?) explicitly state that it's not for use on stainless, presumably because it's harder than the mild steel that seems to be the standard.

Thread drift 2: while at the parts store buying fittings for my friend's repair, the sales guy showed me some of the new copper-nickel tubing, so it's apparently on sale here now. Has anyone had any experience with safety inspections on a car that has had this tubing used? We didn't use it because his pickup is 20 years old and the tubing was very expensive, but if I end up having to replace a line on a car I plan on keeping a long time, this might be a good option.

nate

I'd agree with that but this seems to be kind of an "inspector discretion" thing so lacking a friend who's a certified inspector I still don't really have any backup for my position...

yes, that seems like a more sensible law... but that seems to also prohibit the new copper-nickel stuff which sounds like a bad idea on the face of it but apparently does not have the work-hardening characteristics that one would expect from a copper alloy, and the thought of being able to use a nice soft metal that doesn't rust is very appealing.

nate

yes brake lines seem to be softer now. the 25ft roll we sell is much softer than the straight pieces we sell too

Mastercool hydraulic for on car stuff, if I am at the bench a Sealey PFT07 Both make a flare that looks factory with very little effort. The only bad flare the Sealy did was because the tubing was made wrong.

Cunifer is legal in NY. I use it on some vehicles and it polishes up nice and doesn't corrode like steel. It's been in use on some imports for a while. It is MUCH easier to bend and form than steel.

I drool every time I see that set in a tool catalog, but I know the cost to "me using it" ratio is nearly infinite, so I don't have one.

I think Kent-Moore makes/made a nice set too, or maybe it was superseded by the Mastercool. GW

It was a "I've had it with this CHEAP POS flare tool" purchase. Took about 2 flares and a GM fuel line and it became a "Why in the hell didn't you buy this before" item.

It is great for making just about any flare needed. If you do one set of lines for one car it pays for itself in flare quality very fast. The bench unit is faster in most respects but not good under a vehicle.

Got curious and googled on this subject. Lots of opinions of course. Looks like there really isn't any reason not to use compression fittings as far as them coming apart, the only issue seemed to be leaking if the compression fittings are over-compressed. People don't like their brake fluid leaking out. And don't use brass on steel tubing. So when all is said it looks like it can be done safely if you pay attention to what you are doing but that still doesn't answer the "is it legal" question. I'd guess the reason it's not legal, if it fact it's not, is because there is an SAE spec on braking systems requiring double flare fittings and that the SAE spec is incorporated by reference into the safety regs.

Full employment acts for shops and bureaucrats. A sad byproduct of nanny states.

technically, the conical flare junction can seal better than a radial compression junction. compression may work ok most of the time, but it relies on surface finish quality which is not controlled and therefore the failure rate is higher.