Ok, I've given braided pipe a fair bit of stick lately but some of you are stuck with the bloody stuff and don't have a choice so here goes.
Braided PTFE pipe, otherwise known as "shiny silver brake hoses" is great stuff, for brakes. Don't get me wrong because it does have its uses, just not as high pressure nitrous oxide transfer pipe.
Part of the reason you think its so good is because you don't think it leaks, well bear in mind that with a brake circuit its only under pressure for a few seconds at a time and dealing with a far thicker fluid than nitrous, you also don't think it expands, well compared to reinforced rubber it doesn't, compared to plastic it expands a lot !
For a technical post on why it’s not all that good despite appearances look here;
*******post link here*******Now on to the nasty job of fixing the stuff.
CAUTION: Nitrous leaks can cause cold burns. These aren't nice nor as funny as they sound. Stay away from leaking nitrous and if it's white with frost then don't touch it !
WARNING: You are now entering a minefieldI'll bet you thought pipe was standardised didn't you ?
Oh boy, have I got news for you !
If you're starting from scratch then make life easy for yourself and buy the hose and fittings from one place, if you don't know what size you want then this is a good test of how good the dealer is.
He should ask how long the pipe will be, if he just says "you want -3 mate" then walk away.
Funnily enough a company not very far away happens to make, sell and specify all manner of braided pipes if only you asked them, you'll find the phone number at the bottom of every page
If however you're repairing a hose then the first thing you need to do is very carefully look for a name, hopefully it'll be written on the end fitting and find a dealer of that brand.
If there isn't a name then you need to cut and measure the hose.
Wrap a piece of paper masking tape as tightly as possible around the hose.
Using a Dremel or similar with a cutting disc in it, carefully cut straight through the pipe in the middle of the taped area.
As accurately as you can measure both the internal and external diameter of the pipe and if you can the thickness of the PTFE liner (the white stuff)
OR
take or send the cut end to a local pipe supplier and see if their stuff is the same size.
As a rough guide if it’s metric and is 3.5mm inside, 6.45mm outside for example then it’s Goodridge
If it’s imperial and its 3.1mm inside then it’s probably Earls, you need to check on the wall thickness to be sure. If its 0.76mm thick then it isn't Earls but it is American, if its 1mm thick then life just got easier and it is Earls.
Common internal pipe sizes and names;
Goodridge (metric)
2mm = -02
3.5mm = -03
5mm = -04
Earls (imperial)
5/64ths (1.984mm) = -2
1/8th (3.175mm) = -3
3/16th (4.763mm) = -4
Now you know the size of the pipe and who made it or near enough !
Now check if your fittings have hexes for spanners or if they look like they were crimped on by machine, if they were crimped on then you need a new end fitting, if they were done up with two spanners you just need some spare olives.
And we haven't even got dirty yet ! Good fun this braided pipe isn't it ?
Right then, putting ends on the stuff;*Tightly wrap 1 1/2" masking tape where you want to cut it.
*Using a Dremel with a cutting disc or an angle grinder with a "laser" disc (a 1mm thick cutting disc) carefully cut the pipe at as near 90 degrees as you can in the centre of the tape.
*Carefully unwrap the tape, don't disturb the braid.
*Slide the nut on and down the pipe out of the way (make sure it’s the right way around)
*Carefully inspect the cut, trim any wires that are too long with a good pair of wire snips, have a really good look at the PTFE liner, it should have been cut nicely, not ragged. If it’s rough as hell then wrap and cut it again.
*Carefully inspect the fitting, the spigot should be PERFECTLY smooth.
*Hold the fitting in a vice (making this in the car is a real pain)
*Carefully push the pipe onto the fitting spigot, try not to swivel it too much, and try not to just force it on, have a little patience.
*Once it’s on all the way take it off again.
*The wire should have separated from the PTFE liner leaving a gap, tease any remaining stuck wires away from the liner using a little screwdriver or something. DON'T damage the PTFE !
(There is a tool for doing this, but it tends to end up getting banged about and damaged slightly, this damages the PTFE and causes leaks, besides it doesn't help all that much really)
*Make sure there isn't a single wire left stuck to the PTFE.
*Get an olive and push it onto the PTFE liner, It'll be quite a tight fit and will take some shoving on between the wires and onto the PTFE, keep going until it bottoms out on the lip of the olive.
*Push the pipe (with olive) onto the fitting spigot
*Take it off and check the PTFE liner is still bottomed out in the olive
*If it is then put it back on, if it isn't then try again until it is.
*Holding the pipe tightly onto the fitting spigot, add a drop of moly or graphite grease to the threads and wire, just a bit to help it settle without friction.
*Still holding the pipe tightly, push the nut up to the fitting and start turning it clockwise until it grips the threads.
*Tighten the nut until it’s between 0.6mm and 1.1mm from the back up hex (check with the manufacturer of your pipe fittings)
*Job done !
And you wonder why so many leak ! How much care do you think is taken by someone on £4.80 an hour ?
To check for leaksIf the pipe is out of the car then connect one end to the bottle, blank the other end off or connect it to a solenoid and open the bottle.
Coil the whole pipe up and dunk it in a bucket or bath of soapy water, there will be bubbles ! Give it a good swish around and wait for the bubbles to stop.
If one piece keeps bubbling, even if its miles away from the end then you have a leak, it travels under the braided, often for feet ! You can try tightening the pipe nut a little but that rarely works, since its leaking anyway you have little to lose by trying.
If it’s in the car, then get the trusty paintbrush and soapy water out and start painting the pipe, go as far along the pipe as you can looking for bubbles.
Now close the bottle and wait 24 hours, open the bottle very slowly and you shouldn't hear a sound, if you do its leaking somewhere. Out with the paintbrush again and see if you can find the leak.
The best braided tip I can give is leak test the damn thing before running it through the car ! If it leaks then send it back.
Braided pipe fitting tips*Don't force it, let it lie naturally. If you force it to bend or twist you will weaken it.
*Protect anything else from it. It rubs through ANYTHING ! That includes wiring, in a car stick it down to the floor or sill with gaffer tape.
*Protect it from sharp edges. ANYTHING sharp will rub through it !
Rather than use grommets when you have to get it into the engine bay, use something called a "gland compression fitting" you can get them from electrical places, get a "step drill" at the same time for drilling the hole, its the only way of drilling big holes neatly in bodywork.
*Keep it away from heat. Cold nitrous is fast nitrous and that braiding doesn't keep it cool or protect it from heat
*Before connecting it to your solenoid stand on the end or hold it with a rag tightly and open the bottle slightly to blast any crap out of the pipe
*Where it hangs in mid air (like in the engine bay) cable tie it to something. It doesn't like vibration so cable tie or clamp it every 12 inches
*Don't over tighten it, finger tight then about half a flat, as soon as it feels tight IT IS !
*Don't kink it, bend it too tight, twist it, run it near hot things, run it against soft things, run it against sharp things.
*Despite appearances take care of it !
Just think about this for a second, spare olives are pennies each, pipe is about £6 a meter, so whats stopping you practicing and making your own pipes to the EXACT length you need and not having to lose half a mile in an inner wing ?
If you have any constructive critisism then look for the button below that says "post reply" comments are welcomed and I hope its helped someone.
Personally i've got at least a dozen better options than bloody braided pipe thanks, I've had enough of the stuff.
