Technical brake lines

[Pugglt Auld Jock]

Just had another wee thought concerning patching in to a length of pipe - often front to rear. I like to use a connecting block as I've shown in my previous post. What I've also seen done is to use a male connector on the end of one pipe with a No1 flare and a female connector on the other pipe with a No2 flare. I was taught in college not to do this - I forget the reasoning behind it after all these years - and I think MOT inspectors are not keen on it. It seems to be generally frowned on as not good practice so I just don't do it.

 

[jackwhoo]

Just had another wee thought concerning patching in to a length of pipe - often front to rear. I like to use a connecting block as I've shown in my previous post. What I've also seen done is to use a male connector on the end of one pipe with a No1 flare and a female connector on the other pipe with a No2 flare. I was taught in college not to do this - I forget the reasoning behind it after all these years - and I think MOT inspectors are not keen on it. It seems to be generally frowned on as not good practice so I just don't do it.

From memory Citroen 1980s 1990s did the male/female union hard brake line joint at the factory over the rear beam.
But they are French

 

[jackwhoo]

Hmm. I'm just reconsidering your question here Jack and wondering if I got hold of the right end of the stick.

You asked if I use new SAE tube nuts when making new SAE flares.

Well, my "problem" - which has turned out not to really be a problem - is that both my tools produce SAE flares so I have no option to make DIN flares. - I'm very attracted to that DIN tool Frost are doing for 30 something quid though.

Your question sounds a bit "horse before cart" if I can say so without giving offence. So, yes, If I'm making an SAE flare and the tube nut required is an SAE (imperial) thread then I will be using new nuts wherever possible (which is pretty much always. However I may be making an SAE flare on a pipe which I'm going to be using a Metric Tube nut with (which Ideally I probably shouldn't be doing, but it works for me for the reasons in my above earlier post) and I would, in this situation, be using a new metric nut. In other words I will always use a new nut if I can get one and would only consider using a second hand nut if a new one is not obtainable and I had a used one which was in very good condition.

I'm not quite sure if that's the answer you were looking for? If not please do rephrase and ask again.

Hi again,

I wondered if when you made sae flares you fitted a new sae metric tube nut(thanks for reminding me they are called tube nuts I was struggling with correct name) .
Sae tube nuts are available in metric threads and appears to be the Asian car manufacturers way.

The upshot is you have had no problem using din fittings with sae flares.

I think using the din tube nuts give less chance of the nut jamming on the tube making undoing the tube nut without twisting the brake pipe to destruction.
New Brake pipe unions require very little torque to seal correctly.

Apologies for my cart / horse question.


Cheers

Jack

 

[Pugglt Auld Jock]

Very helpful because I was concerned about using sae flares with din nuts-now I am not.

I had a feeling sae flare nuts are fully threaded and din partially threaded this is not correct you have to check visually.

As I said Jack, it's worked for me and I've never had a problem but you need to be aware it's not how it's designed to be done so if it all goes pear shaped you might be in legal trouble? Mind you how anyone could take apart an assembled - and therefore distorted by compression - joint and tell whether it had been made with a DIN or SAE forming tool? Liability wise though you're probably at risk? In other words, if the brown sticky stuff hits the fan don't say I advised you to do it, I'm not, I'm just saying it's worked for me - so far!

Interesting what you say about the partially threaded metric nuts. I used to come across those a lot but of late it's mostly fully threaded ones I've seen. They seem to be interchangeable? so I don't know why they exist? You'll notice that the ones in my spares box are all fully threaded but the one I used in the example of fit is only partial - No reason, just what came out the box!

The really important bit is to produce a nice full well formed flare. Make sure the end of the pipe is cut off nice and square. deburr it well, both inside and out. If you don't deburr the inside the forming tool "PIP" will wear more quickly. Make sure the pipe is fully entered into the forming tool. If it's not inserted to full depth you'll never get a nice "fat" flare and watch the pipe isn't slipping through the clamping of the die as you tighten the forming screw or, again, you'll not get a fully formed flare. A wee dab of lubricant, not mineral oil based - rubber lube works quite well - on the forming end helps get a nice smoother result too and cuts down on tool wear.

 

[Pugglt Auld Jock]

And one final wee safety related thought. When you're all done and the job is finished. Nice shiny new pipes in place to admire, all unions fully tightened, system bled out and then fully pressure checked - that's one of Mrs J's most useful rolls, sitting in the driver's seat pushing down very firmly on the brake pedal whilst I wriggle around under the car checking every single joint for leaks and that's not just the ones I've been fiddling with, and flex hoses for signs of damage or swelling under pressure. I learned to do this when working in the trade. It's very difficult to prove that, when you've been doing brake work and something subsequently fails, even if you've been nowhere near it, that it's not your fault! Anyway it's just good general safety practice.

Even when I'm completely "happy" with everything I will be checking the fluid reservoir level daily for the first few days and then probably a couple of times a week for the next month or so. If it's one of the "family fleet" I've been working on I'll show them the reservoir and insist that they follow my checking regime. Just works for me.

 

[Pugglt Auld Jock]

Sae tube nuts are available in metric threads and appears to be the Asian car manufacturers way.

The upshot is you have had no problem using din fittings with sae flares.

I think using the din tube nuts give less chance of the nut jamming on the tube making undoing the tube nut without twisting the brake pipe to destruction.
New Brake pipe unions require very little torque to seal correctly.

Now you're teaching me something. SAE tube nuts configured with metric threads? Could this be the reason I've never had a problem? I'll be asking some rather more in depth questions next time I'm at the factors!

Brake pipes rotating as you attempt to slacken the nut is a right pain in the backside isn't it? Plenty of Plus gas and a modicum of heat sometimes works but I don't like using heat as it melts the plastic coating used now a days by most manufacturers. Having to replace an otherwise perfect pipe because it's twisted to a dangerous degree is very frustrating isn't it.

I think especially with "soft metal" - copper based metal in other words - you're absolutely bang on to say they require relatively little compression to achieve a seal. In fact if over tightened, in my experience, you are virtually guaranteeing that the pipe will be jammed to the nut when you attempt to undo it! which can be so frustrating if all you're trying to do is renew a wheel cylinder of flex hose. As with so much to do with cars, tightness is a matter of "feel" which either you have or you haven't.

 

[jackwhoo]

Thought about this a bit more. I definately think better off using a DIN tube nut into a DIN fitting as much less likely to jam on the brake pipe plus more nut material pressing onto the flare.

Ah the things we end up pondering upon with the help of different opinions and ideas

 

[Pugglt Auld Jock]

Thought about this a bit more. I definately think better off using a DIN tube nut into a DIN fitting as much less likely to jam on the brake pipe plus more nut material pressing onto the flare.

Ah the things we end up pondering upon with the help of different opinions and ideas

Aye Jack, think I've just about convinced myself to buy that DIN flaring tool!

 

[Pugglt Auld Jock]

But they are French

Says it all really doesn't it! I've never been able to get "enthusiastic" about mass produced French cars.