Fitting a Brake Line (how to)

[stinkwheel]

Tonight I spent one hour and 22 quid on my GPZ500s. The result was taking the brakes from spongy, four finger brakes with a lever coming right back to the bar to rock hard, two finger brakes with an inch of travel.

All this by simply replacing the rubber brake line with a Goodrich braided steel line and bleeding all the air out of the system.

A GPZ500s is a nice simple one, single calliper so here is how I did it. This is not necessarily THE way, but it is MY way.

Health and Safety
Brake fluid is corrosive and flammable, it dissolves paint so wash off any spills immediatley. It absorbs water so keep everything perfectly dry. It is also irritant so wear gloves or apply barrier cream before you start. You should really wear goggles too as it would not be plesant to get in your eye. Dispose of any waste brake fluid with consideration to who might get their hands on it (children/animals) and the environment.

What you need
You need of course to buy your brake line, these are available from many places, I bought mine from Busters online site. They should be able to supply one of the correct length and fittings for your bike. There are a variety of materials for fittings. I have chosen simple braided steel line with cadnium plated steel fittings as I have never had a problem with them, you can also get alloy and stainless fittings.

I also ordered new banjo bolts as they are only a couple of quid, your old ones may well be fine, but you can't tell until you get them off. You MUST use new copper sealing washers, these are supplied with the kit.

You will also need a new bottle of brake fluid. The type to use will be embossed on the top of your master cylinder. I am using DOT4 rather than the DOT3 the manufacturer recommends because I have experienced brake-fade on this bike before. Do not use old brake fluid, it absorbs water over time, Use a new, sealed bottle only.

You will also need a length of clear plastic tubing and a receptacle to catch the waste fluid. The other items are part of my particular way of doing the job and are not strictly necessary.
Stuff you need
https://www.bikechatforums.com/files/bits.jpg

Dismantling
First thing to do is to see if the bleed nipple will loosen. They are prone to corrosion and snap off easily. The bleed nipple is located on the brake calliper, I usually use a socket on this to loosen it initially. Once it is loose, I tighten it back up again, you should see a small amount of brake fluid has 'oozed' out of the end of the nipple as you loosened it, this shows it is not blocked and is good. From here-on in I use a ring spanner to loosen and tighten the nipple.

If the nipple shears off you will need to get a new one and get the bit that is left in extracted/drilled out, this is a pain in the arse. Big sigh of relief from stinkwheel as the nipple loosened off perfectly
Nipple with ring spanner on
https://www.bikechatforums.com/files/nipple_191.jpg

Next obstacle are the two screws in the master cylinder. These are also prone to corrosion and are easily burred, use the correct size screwdriver. It is not uncommon to have to drill the heads off these if they are stuck. In my case, a previous owner had already burred one of them then put it back in . I drilled the head off it with a 6mm drill bit used very slowly and carefully so as not to drill into the alloy casting. The stub usually unscrews with no effort once the lid is off.

Make sure you remove any muck and clean off the outside of the master cylinder before proceeding, muck has no place inside your brakes!

Master cylinder with one screw partially drilled out
https://www.bikechatforums.com/files/master1.jpg

The lid of the master clinder should now lift off.
https://www.bikechatforums.com/files/master2.jpg

Then lift off the rubber bit to reveal the reservoir full of brake fluid. Make sure the bike is level and steady or you might spill it on your tank!
https://www.bikechatforums.com/files/master3.jpg

Now I usually drain down the old brake fluid. I just let gravity do most of the work by attaching a piece of tubing to the nipple (with spanner in place) and opening the nipple, gravity will allow most of the fluid to run out.

Now is a good time to route your new brake line loosely alongside the old one, saves head-scratching later.

Remove the banjo bolts from both the master cylinder and the brake calliper. Use a socket set to do this. A little more brake fluid will escape from round the bottom banjo, I usually just catch this in a cloth.

Ensure the surfaces you have just exposed under the banjo are perfectly clean and throw away the old brake line having transferred any rubber boots and grommets across to the new one.

Fitting the new brake line

Simple enough, attach the new one where the old one was, use a new copper washer each side of the banjo. Remember you are screwing a hard steel bolt into soft alloy so use an appropriatley set torque wrench to avoid stripping the thread.

Filling and bleeding the system

There are several ways of doing this. I use a 3-way tap which you would be able to get from someone who works at a vets/hospital (they cost about two quid) and some drip-set tubing, any clear plastic tubing that fits over the nipple will do.

My way I set up a closed, airtight circuit by attaching one side of the tap to the nipple, one side to a syringe and the third to a pipe leading into the waste container. A 3-way tap allows you to have any two of the three branches connected with the third shut-off. SeeRED TEXT.

You can also do it the traditional way without a 3-way tap. (see BLUE TEXT

In either case, put some brake fluid into the master cylinder reservoir, you must keep this constantly topped up from now on. If you allow the hole in the bottom to become uncovered, you will draw more air into the system and have to start again.

My way

Three way tap schematic
https://www.bikechatforums.com/files/3-way.jpg

Set the tap so 'off' is at the waste pipe, open the nipple and draw brake fluid down using the syringe. When the syringe is full, turn the tap so 'off' is at the nipple and empty the syringe down the waste. You do not need to close the nipple between times. Continue until there are no bubbles coming out of the nipple.
Stinkwheels brake bleeding circuit
https://www.bikechatforums.com/files/bleed1.jpg

Now close the nipple and pump the brake lever a few times, do it slowly and firmly, if you are too quick you will get a squirt of fluid flying up out of the reservoir when you release the lever. Now tap the calliper with a nylon hammer a couple of times to encourage any bubbles to move to the top, open the nipple and draw down some more fluid in the same way as before (5-10ml is enough). You will see that more air (tiny little bubbles) is being drawn out. Keep doing this until you are getting no more air, you should feel the lever getting firmer and firmer the more air you get out.

The system is now bled, give that man a cigar!.

The traditional way

Attach a length of plastic tubing to the end if the nipple (spanner in place) arrange it so the end of the tubing is in a container with enough brake fluid in to cover the end of the tube.

Apply pressure to the brake lever (slowly and firmly, go too fast and fluid will squirt up out of the reservoir when you release the lever) and as you feel the pressure build, open the nipple. Just before the lever reaches the bar, close the nipple again then slowly release the lever. As you repeat this process, you will see fluid being pushed out into the tubing. Keep going until there is no air coming out of the nipple.

Now pump the lever a few times with the nipple closed, tap the calliper with a nylon hammer and repeat the bleeding process. You will see a few more fine bubbles of air coming out. Keep going at this until there is no more air and the lever has a firm action.

Cigar time

Finishing up
Nip up the nipple with a torque wrench and replace the rubber dust cover. Reassemble the master cylinder reservoir ensuring the brake fluid is up to the level mark in the glass window. Wash any spilled fluid off the calliper.

My job is not quite finished as I nee to buy a set-screw to replace the one I had to drill out.

As a finishing touch, bungee the brake lever down to the bar for a few hours (or overnight). Any remaining small bubbles should work their way up and out of the brake line.
https://www.bikechatforums.com/files/lever.jpg

If the brakes become spongy again, you might need to bleed a bit more fluid out to get rid of any residual air.

This is the simple, by the book way of doing the job. Some callipers are badly designed and can be tricky to get the air out of necessitating filling from the bottom with a syringe or taking the calliper off and tilting it/pushing the pistons in/ shaking it/swearing at it. Some also have more than one nipple, I believe you would normally do the bottom one first in this case but if in doubt, consult your manual.

Tools
I kept all the tools I used to one side as I did this job just to see what you need.
10mm socket
14mm socket
10mm spanner
screwdriver
torque wrench
Nylon hammer
Drill
bleeding kit

https://www.bikechatforums.com/files/tools.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[mr jamez]

[landy.s11a]

Stinkwheel = Mr Haynes

Excellent step by step instruction

want to come to the Isle of Man to do mine?

Lee

[Villers]

Nice one stinkwheel, I had hoped for the same results with the HEL lines I bought for my CBR6 but some bitch smashed it up before they were delivered!!

I take it the rear brake is sensitive enough already without putting on a braided hose?
____________________
RS125 > CBR6 > SV650S > ZX636R > GSX1300RZ Hayabusa > 06 RSVR Mille > SV1000S > Street Triple 765 RS

[stinkwheel]

Rear brake is a rod-actuated drum. Nice and simple and perfectly adequate for the job

EDIT: The 22 quid includes next day delivery (I am going away next week and left myself only just enough time for the 'buggeration' factor such as ordering new nipples etc. Which is why I wasn't waiting for the weekend, if I had, it would have snapped off sure as hell). The parts themselves cost 15 quid.

[fuzz]

Nice one I'm doing the lines on the SV at the weekend. You have most likely saved me some time
____________________
https://www.bikepics.com/members/fuzzbcf/
Bikes: '99 NSR125R, '00 SV650S, K1 GSX-R600, '97 CB500, K3 SV1000S, '16 VFR800

[Major_Grooves]

Nice one. The front brakes on my CB500 have seized at the moment, so I will have to try and strip and clean them. I've never done it before but there are several good guides on here that I will follow. I think I will change to braided lines at the same time using this guide.

Unfortunately I have neither the time nor the money at the moment to do this, so yesterday I spent half an hour spraying WD-40 into the chain of my pushbike which had been abandoned at work for 2 years. I'll be cycling to work for the next few weeks.
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About me|@Major_Grooves|My company|Digg|Flickr

[mchaggis]

A very good howto as usual, but are you sure brake fluid is flammable? I wouldn't have thought flammable brake fluid would be very clever, what with the heat the calipers get to and with hygroscopic tendencies.

Trying to set light to brake fluid is probably another thing on my to do list.
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[stinkwheel]

Well it is a glycol type thingy that is a glorified alcohol. I always assumed it was flammable. Best not to smoke round it anyway, you don't want fag-ash in your brakes.

Methanol is hygroscopic too and pretty damned flammable.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[bish777]

My mother always moaned about me nicking her syringes lol Even though she nicked them from work! (shes a nurse.)
____________________
GSXR1100J

[Major_Grooves]

I must remember to stock-pile some syringes and rubber gloves before I leave this job.
____________________
About me|@Major_Grooves|My company|Digg|Flickr

[Robby]

The old nurse dressing up eh. I like your style.

[wher2guv]

That was a great how-to !