Anyone had this problem with there '08 450


12 replies to this topic
  • Weapon X

Posted May 05, 2009 - 08:28 PM

#1

I would be racing and about 2 laps in and my front brake lever gets stiffer and around lap 4 the front wheel starts locking up, I let a little bit of brake fluid out of the resevoir and I already replaced the stock fluid with belray dot 4. I think this gets worse when I mount my dna rims too, are the spacers out a touch ,not sure what the actual problem is here everything looks straight and spins true. Any help would be appeciated.

  • grayracer513

Posted May 05, 2009 - 09:10 PM

#2

Have you replaced the front brake lever?

  • BC3

Posted May 05, 2009 - 09:39 PM

#3

[COLOR="Blue"]I had this happen to me once and the cause was that the return hole in the master cylinder was plugged......It is the smallest hole in the floor of the master cylinder (there are two holes) either that or your piston isn't returning all the way back and letting the pressure back into the reservoir....you need to have some clearance between the lever and the piston with the lever relaxed.....(free play) Hope this helps [/COLOR]

  • psmith85

Posted May 06, 2009 - 04:05 AM

#4

Is there any reason to think that the rotor might have slight warpage?

  • aj_yz426

Posted May 06, 2009 - 04:37 AM

#5

What BC3 said. I had it happen on an old bike. Rebuild of master cylinder fixed it. Piston wasn't returning all the way. When cool there was a gap or freeplay in the lever, when hot the lever became firm (no freeplay) and the front brake locked up. You might try to drain, clean everything, and replace brake fluid first and if no help, rebuild master cylinder.

  • davcon

Posted May 06, 2009 - 05:51 AM

#6

I've noticed odd behavior as well. The lever becomes stiff then loosens for no apparent reason. Usually just once per ride. Never had the wheel lock up tho. Have to pay more attention to this, sounds like the situation could get worse.

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  • Stepdaddy

Posted May 06, 2009 - 05:56 AM

#7

Happened to me after i changed my break lever out, be careful not to over tighten the bolt that holds on the lever, because the movement of using the front break will actualy tighten it up and lock your front wheel up...I found this out the hard way.

But there are many other things that can cause this problem, this was mine

  • grayracer513

Posted May 06, 2009 - 06:30 AM

#8

Have you replaced the front brake lever?

The reason I ask this is because there is a known issue with some aftermarket replacement levers on the '08. They don't fit the MC plunger correctly, and cause the fill/return port to be blocked off.

Read (From Common Threads):

http://www.thumperta...853#post5844853

  • Weapon X

Posted May 07, 2009 - 02:59 PM

#9

Ya gray I have ASV on the bike ,what should I be looking for?

  • grayracer513

Posted May 07, 2009 - 07:23 PM

#10

Read my post just above yours. The '08 takes a different lever (ASV# BLH13 or BFH313). If that's the one you have, check for the described condition. If you don't have the right one, get it.

  • lanham

Posted May 08, 2009 - 07:44 AM

#11

The reason I ask this is because there is a known issue with some aftermarket replacement levers on the '08. They don't fit the MC plunger correctly, and cause the fill/return port to be blocked off.

Read (From Common Threads):

http://www.thumperta...853#post5844853


I just drilled the hole out bigger to accomodate the plunger.

  • Weapon X

Posted May 12, 2009 - 05:30 PM

#12

looked into it and there is definetly the wrong lever on the bike ,it for the 07 250f only.

  • grayracer513

Posted May 12, 2009 - 06:35 PM

#13

looked into it and there is definetly the wrong lever on the bike ,it for the 07 250f only.

That's an older listing. The '07 YZ250F lever is the correct lever for the '08 YZ450. The '08 450 uses the smaller caliper/master cylinder combo from the '07 YZ250F.

http://www.asvinvent...off_roadc5.html (BLH13)





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