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Brake fluid bleeding query.

22K views 31 replies 20 participants last post by  VenomRR  
#1 ·
So i've just changed the oil and replaced the air filter for the 18000km service and now it's onto the brakes.
All, or most of the how-to threads i've serched for so far state that to bleed the the brakes you should just pump the lever till it's air only. But what I would like to know is - doesn't any fluid stay over in the calipers because the pistons are extended out? Don't you have you remove the calipers, push in the pistons to force all fluid back into the lines and then bleed using a vacuum?

Thanks,
 
G
#2 ·
Do not pump the brakes until it's air only. That will only make bleeding the brakes much more of a headache.

Just bleed the conventional way by applying pressure to the brake lever, then opening the bleed valve and closing it, then repeating that for each side and at the master cylinder until the fluid comes out clean. A vacuum bleeder will work as well with that method.
 
#3 ·
Or just got get the one man bleeder kit from auto parts store. +1 on what Demented said bleed tell the fluid is clean, just make sure the system does not get any air.
 
#4 ·
Do it with 2 people...makes it sooooo much easier. You can do it with one but trust me.......2 is better.
 
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#5 ·
the point of bleeding is to get the air out. why would u pump until there's nothing but air left in there? once u fill it with fluid again, you'll have a ton of air trapped in there. the key to the whole thing is to never let ur reservoir go empty or you'll be starting all over. you want the air out so that when u brake you don't get that mushy feeling. you want a solid feel. with regular oem lines, the rubber will expand under pressure. if air's in there it will make this worse. more air = squeeze a lot harder on the lever in order for enough pressure to be applied to pads. this is why people switch to steel braided lines. heres what you do.

1) get wrench that will fit nut on bleeder (don't lossen the nut yet)
2) attach hose to bleeder nozzle
3) pump ur brake lever a few times and on the last time keep pressure on the lever (hold the brake lever in) and losen bleeder nut. You'll see a little fluid come out along with air bubbles.
4) with the brake lever still pressed in, tighten the bleeder nut.
5) repeat this until you don't see anymore bubbles come out.

** bubbles are bad, you don't want those in there
** MAKE SURE THAT YOUR RESERVOIR DOESN'T GO EMPTY OR YOU'RE GONNA BE DOING THIS FOR A VERY LONG TIME

remember you have 2 callipers in the front and one in the back. bleed them all. if you have no bubbles initially then you're good
 
#6 ·
thanks guys, especially Sadt3arZ on that last post.
If I were to change the fluid for a higher rating one, which method should I use to remove all of the old brake fluid and to refill the new fluid? If I were to use this method, surely the fluid would get mixed, ye?
 
#9 · (Edited)
yeah, I used that video too! found it a few days ago. Thanks though.

Anyone know the capacity of the system? Is there any sure way to know I've flushed out all(most) of the old fluid and have the new one in.
I've just done a bleed and the old fluid wasn't dark and although I removed a few air bubbles at the front(hardly any at the rear), the lever isn't any stronger than before.
I've used about 3 * the fluid in the rear reservoir and 3* the front reservoir at each nipple at the front(left, right, master). All in all about 300ml of brake fluid.
Just asking because now that it's done it seemed too easy.
Oh, and I see that some guys remove the rubber thingy from inside of the reservoir? And when refilling, I fill till just above the LOWER line so that after installing the rubber seal and close it up, the level shows just below the upper line, ye?
 
#11 ·
You can tell your brakes are done bleeding when there isn't any air bubbles coming out of the lines anymore when pumping the brake levers. Also you should feel a good amount of pressure on the levers now when bled right. You will know what I'm talking about if you emptied all the fluid.
 
#12 ·
I just replaced all the brake fluid in my bike. Thanks to the help I found in this forum I realized it is much easier than I thought. I also can't believe the difference it has made in my braking ability. I will be changing my brake fluid more often than the 2 year / 12000 mile recommendation due to the high humidity here. When I looked at the fluid in the reservoir I saw there was water in it and it was much darker than new fluid, that's when I knew that that was why my brakes were feeling spongy. Not anymore though, thanks again.
 
#16 · (Edited)
Correct me if I'm wrong but there isn't a bleed nipple on the stock m/c of an '05-'06 RR is there? There certainly isn't on an '03 anyway.

It's just a case of bleeding each caliper. If you're running stock lines then you'd want to go right caliper first then left; top down (with stock lines, the right caliper feeds the left one). With the 2 line setup it'd be whichever line comes from the m/c first, then the other.

I can highly recommend giving the calipers a full overhaul now and then too though. Did mines just before the winter and, although they aren't perfect, it made a hell of a difference!
 
#21 ·
Just a fyi brake bleeding sucks imo.. id rather adjust my valves!. I just always feel like theres some air left in the system. Reverse bleed is an option too. Seems much better imo buy ive never done it.
 
#24 ·
#26 ·
These tools allow you to use the brake lever to pump out the air, or flush the system. There's a ball valve that suits right next to the nipple, so when you pump the brakes air or fluid is forced out but air can't get back in. Slicker and easier than having to create suction with another tool.

Also, the wrench is part if the same tool, so you don't have to deal with both a wrench and a diction kit.

Again, this just makes bleeding easier, not better. But if you don't yet have the tools and/or you will do this single handed a lot, these are the way to go in my experience.