Ultimate front brake bleeding.


12 replies to this topic
  • earl69

Posted April 14, 2009 - 06:19 PM

#1

I posted about a month ago because I had problems bleeding my front brake on a 2003 YZ 450. Well I tried everything. I put about a quart of brake fluid through the thing, I tried taking off the top banjo, I used a pneumatic brake bleeder, I tried talking nice then dirty but nothing.

Then I was taking off the brake and I noticed when I had the brake lever straight up and down I had brake. When I would lay it sideways, like it would be on the handlebar, I lost my brake. So this is what I did.

I took the front brake completely off. My master cylinder was full.
I put the brake lever/mastercylinder on an old set of handlebars.
I opened the pads as wide as they would go, then I hung the bars so the lever was straight up. I let it sit for about 12 hours then I pumped the brake up and tied off the lever.
I again hung the brake so the lever was up. I noticed when the brake lever was straight up the little 90 degree bend where the top banjo connects into was parallel with the ground. Exactly where a bubble could sit and not go up into the master cylinder. So I moved the handle bars so the top banjo was a bit lower then the bottom of the master cylinder. I tried my best to get a straitght line from the caliper to the very top of the master cylinder.

24 hours later I have a full brake. :p

It make sense to allow the air to do what it naturally wants to do. It will self bleed in a day or so and you will have a great brake.

Cheers

earl

  • mandark

Posted April 14, 2009 - 06:46 PM

#2

Oh sure...write your post right AFTER I take my front brakes apart because of the same symptom, LOL!

I'll give that a try tomorrow. Thanks for the post. Good gas comin at ya

  • Burnrider

Posted April 14, 2009 - 06:49 PM

#3

I think this is why some of us opted to drill a 2nd hole in the banjo bolt at 12 o'clock.

  • mandark

Posted April 14, 2009 - 06:52 PM

#4

I think this is why some of us opted to drill a 2nd hole in the banjo bolt at 12 o'clock.



What the hell does lunchtime have to do with it?! :p
















J/K

  • 2001YZF426Rider

Posted April 14, 2009 - 07:13 PM

#5

Another trick is force the new brake fluid in from the bleeder valve, that pushes the air out through the master cylinder.

  • CaptainKnobby

Posted April 15, 2009 - 07:45 AM

#6

I dont see how you all are having this problem. I put new pads on the front and rear and changed the brake fluid out also.

All i done was took the cap off and pulled the diafram out. Then took a clear plastic tube and slipped it over the bleeder nipple and let it hang over a bowl.

Then I just applied brake pressure and opened up the bleeder and fluid shot out and then closed the bleeder back up. Done it two more times and then added some new fluid.

Bled it some more and added more. Done this till I used a half bottle of fluid to make sure I had all new fluid in.

That was it and all was fine and no problems.

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  • mandark

Posted April 15, 2009 - 11:55 AM

#7

I dont see how you all are having this problem. I put new pads on the front and rear and changed the brake fluid out also.

All i done was took the cap off and pulled the diafram out. Then took a clear plastic tube and slipped it over the bleeder nipple and let it hang over a bowl.

Then I just applied brake pressure and opened up the bleeder and fluid shot out and then closed the bleeder back up. Done it two more times and then added some new fluid.

Bled it some more and added more. Done this till I used a half bottle of fluid to make sure I had all new fluid in.

That was it and all was fine and no problems.


You don't "see" because you have no clue what happened to mine. I only mentioned that I had the same symptoms. I never mentioned what caused the problem.

What "caused" the problem, and resulted in the need for a complete rebuild of the caliper assembly and master cylinder up front, with the rear caliper assembly ultimately requiring complete and total replacement?

My bike was stolen and thrashed for 16+ months by a moronic thief who knew nothing about motorcycles. A fact which he aptly demonstrated by using a lawnmower sparkplug instead of the proper one, using cooking oil on the air filter, and ******* LARD as chain lubricant. (no joking)

So...it would seem as if the "maintenance" you did to yours was just a little bit different than what I had to do to mine. Congrats on your smooth maintenance procedure results, though.

  • CaptainKnobby

Posted April 15, 2009 - 12:41 PM

#8

You are lucky just to get by with a caliper rebuild.... Running the bike on a lawn mower plug and using corn oil for air filter oil:jawdrop: Its a wonder if it will still run right.

I would find that theif and make him pay for the damages.

  • mandark

Posted April 15, 2009 - 02:46 PM

#9

You are lucky just to get by with a caliper rebuild.... Running the bike on a lawn mower plug and using corn oil for air filter oil:jawdrop: Its a wonder if it will still run right.

I would find that theif and make him pay for the damages.



Let's just say the caliper rebuild is just one of the minor repairs I had to make when I got it back...

http://www.thumperta...t=740671&page=2

  • earl69

Posted April 15, 2009 - 04:17 PM

#10

I had to replace the piston in the master cylinder. I think I had a bunch of air after that.

I had gone through post after post and couldn't find a solution.

earl

  • grayracer513

Posted April 15, 2009 - 05:25 PM

#11

This works for me:

http://www.thumperta...ad.php?t=499749

  • earl69

Posted April 15, 2009 - 06:16 PM

#12

Gray

I read that about 10 times. I couldn't figure out what to do with the brake line after I disconnected it. I was concerned that I would get air in the line by taking it off. When I would bleed the banjo, under pressure, I would get a bunch of brake fluid flying all over the place.

earl

  • grayracer513

Posted April 15, 2009 - 07:52 PM

#13

When I used that method last, it was to fill and bleed the system after replacing the front brake line, which, of course, was completely empty. Once you get fluid to start flowing down the line on its own, it will do a fairly good job of pushing the air out in front of it. If you also crack the lower banjo bolt loose while the fluid is flowing, it will chase the air from that point as well. Then, "tickling" the lever should pop the last of it up.





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