How much fluid do you (I) need when swapping brake hoses?

Answer: 2 L! To find out why, read on (and no - to avoid air getting into the lines I didn't decide to do the whole thing submersed in brake fluid).

Today I embarked on the task of swapping my stock lines for some nice Goodridge braided lines from eBay. Got everything I needed: fluid, small hosepipe, waste container, 5000 chemical resistant gloves, absorbent tissue, etc...

Covered all parts of the bike in absorbent tissue to protect it form any squirts, drips, etc...

Got rid of all the old fluid by pumping it with the lever through the bleed nuts via the hosepipe into the waste canister and the old lines came off OK (with a bit of elbow grease). Chuck them in the bin - remembering to salvage any holding brackets.

Attach the new lines loosely, remembering all the washers, then - after much deliberation and reorganisation to get the lines looking as cool as possible - switch back to the first arrangement. Turn the wheel from lock to lock and jump up and down on the suspension a bit to make sure the lines don't get caught anywhere and tighten the nuts nice and tight.

I chose the syringe method to fill the lines so filled my syringe up with brake fluid and attached it via the hose to the bleed nut. Loosen the bleed nut and squeeze the syringe until you get fluid coming out in the reservoir. Tighten the nut and repeat on the other side.

With my lines full of fresh fluid I though it would be a good idea to rinse out the reservoir with brake fluid. Syringed out all the brown cr*ppy fluid and syringed it straight in to the pot of brand new new brake fluid - d'oh!! So its a car drive through rush hour traffic to Halfords and an extra £8 to Mr. Castrol. So that's 2 L of fluid of which I only needed about 100 mL.

With the brief diversion over I topped the reservoir up - pumped it a few times - until no more little bubbles came up from the bottom of the reservoir. With no firm response from the lever its bleeding time. All it took was once bleeding cycle on each side and the lever was firm as [with the hose attached to bleeding nut: 1) undo bleed nut, 2) squeeze and hold lever - stuff comes out of the bleed nuts, 3) tighten bleed nut, 4) release brake lever].

I'll save doing the back brake 'til next weekend!

Anyway - hope this helps anyone who wants to fit new brake lines - I found it really quite easy. I think it seems a lot more intimidating than it is because it's the brakes - I mean if it was the horn it wouldn't be the end of the world if something went wrong!

a1istair

glad you had such an easy experience. I filled the lines up from the reservoir using the traditional non syringe method. I dont know how many times ive pumped the lever and im still only getting slight resistance. The bubbles seem to have stopped for the moment so ive come inside to see if leaving it a while will make any difference. Sounds like using a syringe is the way forward.

[Viney]

Its an art form. One that i can now replace a set of lines with about half a litre of fluid using the old spanner on nipple tecnique!!! (Fnarr fanrr)

[Luckypants]

Originally Posted by robchester

glad you had such an easy experience. I filled the lines up from the reservoir using the traditional non syringe method. I dont know how many times ive pumped the lever and im still only getting slight resistance. The bubbles seem to have stopped for the moment so ive come inside to see if leaving it a while will make any difference. Sounds like using a syringe is the way forward.

Did mine yesterday Rob. Had the same 'no resistance' problem, even though clear fluid coming through the bleed nipples. I zip tied the lever back to the bar overnight and hey presto, this morning was all sorted by the brake fairies!

You might want to try that.

Cheers Mike, think i might try that - have had it pulled in for the last couple of days but forgot that you had to make sure the system was fully primed first doh!

I've just bought some HEL brake lines, I'm not sure whether I should get the bike shop to put them on or have a go myself using my limited mechanical knowledge. Having read your write up I'm tempted to have a go myself and maybe learn a thing or two.

I've got one question though, the bolt that goes through the end of the hoses, each have a small hole through the diameter, do these holes have to lined up with the hoses or does the position not matter? I know I havn't explained this very well, but hopefully I've got the point across?

Cheers

Will

[Viney]

Brakes are not to be messed with. If you do not know what you are doing, then dont mess with them.!!!

Get someone who knows what theya re doing help you out!

[Bluepete]

Pardon?

Originally Posted by Viney

Brakes are not to be messed with. If you do not know what you are doing, then dont mess with them.!!!

Get someone who knows what theya re doing help you out!

Like you...

[northwind]

Originally Posted by Viney

Brakes are not to be messed with. If you do not know what you are doing, then dont mess with them.!!!

I kind of agree, but on the other hand the first time I did it I knew very little about it, and it worked out fine- though it took me about 3 hours It's possible to learn by doing... But you need to have the right attitude to it. If I'd not got a result I'd've had it off to the dealers, I wouldn't have been happy with less than perfect and I certainly wouldn't have ridden it if I wasn't totally confident in it.