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CrazyMotorcycleGuy
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Is this how I can get air out of my brake lines?
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Is this how I can get air out of my brake lines? - April 20, 2011, 08:56 PM

The bike was sitting about 5 weeks or so when I was out of town. I came back and the brake is very spungy. I think some air got in the lines? So... is this a proper way to get it out?

-pull in the brake lever tight. Loosen the bleeder valve on one caliper and let the air escape... Then tighten, clean off a little of the brake fluid that comes out. Do the same on the other caliper.

-If this doesn't improve things drastically; keep the lever tight. Loosen the valve near the master cylinder. Let some air and brake fluid come out. Tighten.

Does this sound like a decent plan?
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April 20, 2011, 09:03 PM

I'm no mechanic,but I didn't think air could enter a brake system from just sitting.Actually,I would be pretty concerned.


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April 20, 2011, 09:06 PM

Quote:
Originally Posted by C2H5OH View Post
I'm no mechanic,but I didn't think air could enter a brake system from just sitting.
Neither could I, but that is the only thing I can think of as to why my front brakes would be so soft... I wonder what else it could be? The brakes were perfect before I left, and the bike has not been touched or moved during those 5 weeks.
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April 20, 2011, 09:12 PM

How old are your lines? 5 weeks seems way too short for anything that drastic to happen


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April 20, 2011, 09:14 PM

May not be air, may be water (moisture) Condensation can build up if there was any air in it previously, with the temp changes we have been having it wouldnt surprise me.

Also search youtube for bleed procedures there are a ton of videos showing you how to do it properly.
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April 20, 2011, 09:20 PM

Lots of possibilities. Another besides air would be that the caliper pistons are really dirty and the piston seals are sticking. This causes the pistons to retract to far when the lever is released.
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April 20, 2011, 10:27 PM

I got good brake bleeder/pump from Advanced Auto...researched it a bit. Good kit for $40 iirc, I'll lookup the model number if you want
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April 21, 2011, 04:43 AM



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April 21, 2011, 08:44 AM

Quote:
Originally Posted by Witold View Post
The bike was sitting about 5 weeks or so when I was out of town. I came back and the brake is very spungy. I think some air got in the lines? So... is this a proper way to get it out?

-pull in the brake lever tight. Loosen the bleeder valve on one caliper and let the air escape... Then tighten, clean off a little of the brake fluid that comes out. Do the same on the other caliper.

-If this doesn't improve things drastically; keep the lever tight. Loosen the valve near the master cylinder. Let some air and brake fluid come out. Tighten.

Does this sound like a decent plan?

You have CONCEPT down...the video should help you more.

BRAKE FLUID WILL EAT RUBBER/PLASTIC VERY FAST...COVER UP YOUR RESERVOIR UNDERNEATH WITH FOIL...

put some rags/foil around reservoir for protection
Take off reservoir cover
pump lever 3x and HOLD
open valve until brake lever goes all the way down to handle
close valve
let go to lever
repeat (re pump lever) and keep an eye of fluid level in resevior...don't let it empty out.

Just don't spill brake fluid every where...keep extra rags nearby


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Last edited by TalkofDC; April 21, 2011 at 08:46 AM..
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April 21, 2011, 09:05 AM

^ Okay NOW i'm SCRATCHING MY HEAD???

I've spilled brake FLUID everywhere scrambling to clean it up...they have managed to bleed the bike spill free and when the did spill, they weren't panicing...Are there fluids that are not as corrosive to the bike???

also I like that bleed bag...I'll have to get one of those...


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April 21, 2011, 09:26 AM

speed bleeders and a bleed bag ftw! do my brakes in minutes.. if that.


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April 21, 2011, 09:35 AM

Brake fluid is extremely bad for paint. If you let it sit there overnight it will start to lift it. The good news is that even if you spill some (and you most likely will), you can just let it sit there while you work (it doesn't do damage over short time) and clean it up afterwards doing this:

make sure all your bleeders and reservoir cap are back in place properly fastened, then simply use chemistry: brake fluid is extremely hygroscopic, meaning it likes to absorb water (which is a bad thing when it is inside your brake lines as water will boil, opposite of what you want your brake lines to do), so hosing the bike down after you do brake work is a idiot proof way to get rid of any drops of brake fluid from it. I ALWAYS do that even when I am SURE I didn't spill anything.

So basically drench the fregging bike (no hi pressure, just let the water run over the area that might have received a drop) and then you're good to go.

As for how to do it there is a little more to be said:

1) you normally have bleeding valves on each caliper AND in the master cylinder assemby, make sure to start from the lowest one and work your way up (the air bubbles will try to go upwards).

2) sometimes the bleeders are placed in stupid places and don't do a good job, especially in the calipers, a good thing to do is to dissemble the calipers and move them around so to direct any air towards the brake line so it can escape by going up.

3) monitor the brake fluid level in the reservoir closely, if it goes empty you get a shitton (metric standards ) of air in the system and have to start again.

DON'T close the bleeders like there is no tomorrow, they are threaded in aluminum and will strip it. Once it seats give it a little more force and that's it.


As a last resort you can try and force all the liquid in the calipers up by prying the cylinders open with a flat screwdriver in between the brake pads (be careful not to damage them). That shoves a good amount of brake fluid back into the reservoir getting trapped air bubbles with it along the way. In this case make sure the reservoir doesn't overflow.

One last thing, be careful when the level in the reservoir is low and you pump the lever: as the thing starts working again it can (depending on how it is built) start squirting fluid back, normally in your face... If that happens just pretend you're your bike and drench yourself, lol


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April 21, 2011, 09:37 AM

Quote:
Originally Posted by onel0wcubn View Post
speed bleeders and a bleed bag ftw! do my brakes in minutes.. if that.
They do not work as well as a thorough manual bleeding, I can guarantee you that, especially on a bike: in a car the lines are horizontal for the most part, but bikes have vertical systems. On top of that, in 8 years in the racing business in Italy I have NEVER seen a team (bikes OR cars) using one of those, if that says anything. I prefer to do it myself and save the money too


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April 21, 2011, 09:38 AM

That is a good technique and I think the manual has it the same way .. I personally like using the craftsman brake bleeding kit which is so much easy and gets it done much fast if you are replacing brake oil


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April 21, 2011, 11:35 AM

Quote:
Originally Posted by Leoallafila View Post
As for how to do it there is a little more to be said:

1) you normally have bleeding valves on each caliper AND in the master cylinder assemby, make sure to start from the lowest one and work your way up (the air bubbles will try to go upwards).

2) sometimes the bleeders are placed in stupid places and don't do a good job, especially in the calipers, a good thing to do is to dissemble the calipers and move them around so to direct any air towards the brake line so it can escape by going up.

3) monitor the brake fluid level in the reservoir closely, if it goes empty you get a shitton (metric standards ) of air in the system and have to start again.

FYI for all...

This is OPPOSITE of what SBTG video said to do...start at TOP (MC) and work your way DOWN (Caliper)

I'm sure it doesn't really matter as long as you do it right.


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