yz 450 rear brake question

7 replies to this topic
  • ktown yamaha

Posted May 27, 2008 - 05:17 PM


got my self a 06 yz450f, but my rear brake doesnt want to work, its getting oil to it, but yet it will not engage, thinking i should take aapart the brake and clean it all? but not sure, wut would u guys do.

  • sparkyz

Posted May 27, 2008 - 06:20 PM


Start by bleeding the brakes if you haven't already.

  • Ga426owner

Posted May 28, 2008 - 06:14 AM


Start by bleeding the brakes if you haven't already.

agree - use a good quality brake fluid after checking for leaks around the master cyl and caliper
check the rear pads

  • grayracer513

Posted May 28, 2008 - 07:11 AM


You need to go all the way back to the start and provide some better info as to what it isn't doing beyond "doesn't want to work".

Does the pedal travel a normal amount, have a firm feel, but the brake has less stopping power than it should?

Or does the pedal feel soft or springy and never really apply any pressure to anything?

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  • ktown yamaha

Posted May 28, 2008 - 03:22 PM


the pedel feels very springy, it feels as though there is nothing there. I bled the brakes twice with no results.

  • grayracer513

Posted May 28, 2008 - 03:40 PM


Look at the way the rear brake hose runs. There is a high spot in the fluid path right at the hose fitting on the master cylinder. Fluid will flow under the air bubble that forms there forever until you get rid of it.

Be sure the cylinder stays full during bleeding. Loosen the fitting at the M/C about a half turn, then, using a screwdriver, push the rear pads away from the rotor a ways. You should see air come from the fitting. Next, with the fitting still loose, push one full stroke on the pedal, hold it down, and tighten the fitting. The brake will now be much more completely bled, and further bleeding will produce a much better feel.

Remember that you will need to pump the pads back down against the rotor.

  • ktown yamaha

Posted May 28, 2008 - 04:05 PM


ill have to get out there and try it thanks

  • nathanyzf426

Posted May 29, 2008 - 12:21 AM


and if that aint the problem as greyracer has explained it kind of sound like you have done the slave seal in the master cylinder itself you can get a rebuild kit for them or you could try ebay or a bike wreckers for another one hope this might help cheers mate nathan

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