Soft Front brake


16 replies to this topic
  • gawarrior

Posted December 13, 2004 - 07:29 PM

#1

My WR426 front brake has for some reason gotten really soft. Maybe it has been that way but I really noticed it this weekend at my first Harescramble. I have bled the fluid and it didn't seem to have air in the line. I will get some more fluid tomorrow and keep bleeding it to see if it gets stiffer. But I would say it goes at least an inch to an inch and a half before it even starts to engage, then pretty much have to squeeze it all the way to the bars to stop. Quite frustrating. I am used to my R1 where it just takes 1 finger to come to a stop.

And suggestions or help would be greatly appreciated.

  • gawarrior

Posted December 13, 2004 - 08:41 PM

#2

nevermind. I have been reading lots of threads on this. It seems that the Yamaha just has softer brakes unless you do some mods. I am going to try bleeding it first then if that doesn't help I will get some steel braided lines. And then go from there.

  • Gadsen

Posted December 13, 2004 - 09:11 PM

#3

Check for a frozen piston caliper or a floating caliper that no longer floats. (this is its able to slide on the pins) and make sure the master cylinder is comong all the way back to the end. It needs to expose the replenishing port, or it wont take anothe gulp or release fully. Basically, just make sure there is free play at the lever. Any of these conditions will create the trouble you speak of.

  • oldbones

Posted December 13, 2004 - 09:20 PM

#4

This happened to me recently when I crashed and the bike spent a little too much time upside down. I had to bleed the heck out of the brakes before they came back to firm. Even then, they seemed a little softer than before. After my next ride, I noticed some dust sticking to the brake line right where it comes out of the master cylinder... A SUPER small leak had developed there. I tightened the banjo bolt, bled em again, and BAM, they were back.

Check your entire system for any signs of leakage. Squeeze the brake all the way, and hold pressure on it for a while. That makes it easier to find a leak.

Happy hunting!

  • Chas_M

Posted December 13, 2004 - 10:43 PM

#5

A simple little trick for getting rid of soft brakes that often works wonders for many bikes is to turn bars so that the master cylinder is close to the highest point, then carefully pry the brake pads away from the rotor with a large screwdriver, then pump brakes until firm. Repeat a couple of times. What this accomplishes is to force brake fluid together with air bubbles out into the master cylinder reservoir thus firming up the brakes.

  • Dan_Lorenze

Posted December 14, 2004 - 06:20 AM

#6

You should check to see of your rotor is perfectly straight, a bent rotor spinning gradually opens up the piston and gives you a bad brake feel, if that doesn't help I would put new fluid in a bleed the whole system..

  • gawarrior

Posted December 14, 2004 - 08:38 AM

#7

Thanks a lot fellas. I am going to try all of the above tonight when I get home. Hopefully I can get them a little firmer than they are now.

  • BrandonW

Posted December 14, 2004 - 10:34 AM

#8

You should check to see of your rotor is perfectly straight, a bent rotor spinning gradually opens up the piston and gives you a bad brake feel, if that doesn't help I would put new fluid in a bleed the whole system..


This is exactly what I was going to suggest. I have heard of bent rotors being the #1 cause for SBS (spongy brake syndrome).

:cry:

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  • gawarrior

Posted December 14, 2004 - 10:43 AM

#9

I will definately check that too. I have a disc dsp disc guard, but as much as I bust my butt I may have bent it some. :cry: I will see tonight.

  • pattch

Posted December 14, 2004 - 11:45 AM

#10

I have the same problem on my 01' 426 and will try those solutions.

  • gawarrior

Posted December 14, 2004 - 12:01 PM

#11

And I thought it was just me. Hopefully one of these solutions will get me a firmer feeling front brake.

  • Jackazz

Posted December 14, 2004 - 12:21 PM

#12

My guess is that a good "proper" bleeding w/ new fluid will get it back, but if you want it to stay that way for any length of time you probably want to switch to a direct (CR style) routed braided line. I'm planning on switching as soon as I can afford it. IMHO, the way the stock brake line is routed seems like it lends itself to problems, I know that the lever on my '04 is quite a bit mushier than it was when new, & it has less than 200 miles on it. My buddy with an '02 wr426 has had the exact same symptoms as yours & has bled his several times, only to see an improvement that fades away fairly fast. Neither of our rotors are bent (at least not detectable by eye, while spinning wheel with bike on stand). He may need new seals in his caliper & MC, but I would hope that my '04 with less than 200 miles on it does not... :cry:

  • jerryls

Posted December 14, 2004 - 01:34 PM

#13

Assuming you don't have a leak or other mechanical difficulties, here's my low tech approach: The night before I go riding, I use a zip-ty to pull the brake lever up against the grip. In the morning cut it off and the brakes are nice and firm. :cry:

Bleed your brakes occasionally in addition to this method.

  • ETP

Posted December 14, 2004 - 06:42 PM

#14

Sometimes these front brakes will get a stubborn air bubble in them and next to impossible to bleed. One time at a race, we had to remove the entire brake assembly off a bike and hold it upside down to get it to bleed out. Spent about 4 hours inspecting parts and bleeding before we tried the upside down trick. A power bleeder would work for this too.

  • gawarrior

Posted December 17, 2004 - 06:21 PM

#15

Assuming you don't have a leak or other mechanical difficulties, here's my low tech approach: The night before I go riding, I use a zip-ty to pull the brake lever up against the grip. In the morning cut it off and the brakes are nice and firm. :cry:

Bleed your brakes occasionally in addition to this method.



Yeah, I did that. It actually works pretty good. I wonder how long it will last though. I am planning on getting steel braided lines pretty soon so I hope that helps too. I am not sure about the CR routing. I have read good and bad on it. And there doesn't seem to be a 100% conclusion that it does help better than stock routing.

  • drewpeacock

Posted December 17, 2004 - 07:49 PM

#16

Same problem with my wifes 250f and my old 426. I heard I needed to rebuild the master cylinder or pick up new O-rings. I will try your recommendations first. We've lived with spongy brakes for too long. Please write back if you have any luck. Thanks...

  • gawarrior

Posted December 19, 2004 - 07:54 PM

#17

Same problem with my wifes 250f and my old 426. I heard I needed to rebuild the master cylinder or pick up new O-rings. I will try your recommendations first. We've lived with spongy brakes for too long. Please write back if you have any luck. Thanks...


I did flush the brakes some. And then I tryed the zip ty the brake lever to the throttle method. It did seem to help firm them up some for sure. But still not like I want. I am hoping to get steel braided lines soon. I hope that helps even more.




 
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