New brake fluid

[UnknownStuntm...]

So I have looked at Korn's guide and it's pretty much what I have been doing. I'm wondering what's the best way to change the fluid though. Should I unscrew everything and drain the fluid out, clean it all, then replace and try to get it bled OR shall I just pull new fluid down the line and bleed the old stuff out of the callipers?

I realise the first method will be less effort bleeding, and the second method might leave some old stuff in there. Which is more of a ball ache?

Oh, RGV250 by the way.

[supZ]

flush it through, you dont want to empty it all out and then fill it back up. bit of a ball ache there.

an easy way is to open the res., attach a hose to the bleed nipple into a jar or something similar, then crack the nipple and pump the brake. as the res. gets low top it back up with fresh fluid. do this until you're only getting fresh out of the hose.. do the same with the other caliper to ensure all the old stuffs out.

then nip everything up and then bleed as normal to be sure.

personally i do it the other way (reverse bleeding) using a syringe and a bit of hose. i push fluid up through the bleed nipple, fill the res. then empty it. i do this until there is only fresh coming up in to the res. then top it up to the right level and job done. i sometimes bleed normally again just to be 100% but if done right it shouldnt be necessary,
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CBR954RR - Daily toy
CBR600RR - Trackbike

[Vincent]

I'd want to get all the old fluid out before sticking the fresh stuff in there to avoid contamination.
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Space Is Deep

[UnknownStuntm...]

See, that's two replies, one for each method!

I'm tempted to drain everything out, the bike has been stood for a while, but I'm exceedingly worried about forever having spongy brakes.

[Vincent]

[flumpy7]

If youre gonna empty the system completely i would reverse fill with a syringe when putting in the new fluid. Much quicker than all that pumping. Either that or use a mitivac to fill the system then bleed traditionally. Personally i haven't looked back since i first tried reverse bleeding/filling.
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2012 Sinnis apache

[carvell]

[Vincent]

[carvell]

I'm not suggesting you just top it up.

To change the brake fluid, I'd suck out what I could out of the master cylinder, then bleed the whole lot through until new stuff comes out of the bleed nipple.

Much easier and less faff than draining the entire system first.
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Yamaha TDM 850

[stevo as b4]

If your going to do any work on the hyrdraulic side of the brakes, then obviously drain out all of the old fluid first. If you only wanting to change the fluid itself, then i see no problem with using the new fluid to fully flush the braking lines and system, until your sure your getting only clean fresh fluid at either end. You can use a whole litre bottle if you must to make sure you completely change all the fluid, but it will take much less than this typically to achieve a full fluid change.

This is the method that everyone i know, uses on car braking systems, i've never heard of anyone pumping out all the old fluid, and then starting again with new fluid, probably because of what a total ballache it is to fully bleed the system again.

[supZ]

[UnknownStuntm...]

Well since the jury is split and unlikely to make a decision soon I'm just gonna pull out what I can from the reservoir with a syringe, fill that up with fresh, then crack the nipple with 2 banjos and wait till fresh stuff comes out, topping up as necessary, then tighten and do the other side.

To be fair, I've degunged the pistons both sides and there is a very small amount of pitting on some of them. Until I put new ones in, I think I'll just stick to bleeding the fluid through.

Cheers all

[Vincent]

[jay12329]

Having to bleed a dry system is a real pain in the arse. There is no reason that topping up and bleeding though until the stuff going out the bottom is the same colour as the stuff you are putting in the top is any less effective than a dry bleed.
It takes about 10mins this way, much better than the hours spent pissing about with a dry system.

HTH
J