Front Brake ????

[gumby302ho]

  I was coming back from a ride with my daughter today and didnt figure it out right away but my front brake was fading, I was glad to find out just before we got back home. Now there is nothing, no pressure, no leaks, proper fluid level, everything seems perfect. I am thinking master cylinder piston/cups have failed but I have never seen a master work great one minute then fried the next. Am I missing something........ anti dive     

[Tuneforkfreak]

Sounds like it's time to take a look see. Weird scenario for sure

[ribbert]

  I was coming back from a ride with my daughter today and didnt figure it out right away but my front brake was fading, I was glad to find out just before we got back home. Now there is nothing, no pressure, no leaks, proper fluid level, everything seems perfect. I am thinking master cylinder piston/cups have failed but I have never seen a master work great one minute then fried the next. Am I missing something........ anti dive     

M/C's can fail internally. That is, no external leaks and full of fluid.

Noel

[the fan]

I have never had one apart, but could the anti dive be leaking internally?

[red]

I have never had one apart, but could the anti dive be leaking internally?

The Fan,

I have.  The brake fluid would then be going into the front forks, but only in droplets, not the total loss of brake pressure that the OP has reported.  If a master cylinder seal fails, it can be all at once, as reported.  The most likely cause would be some grit in the brake fluid, causing a leak in the same way that front fork seals can leak, caused by dirt.

A MC in otherwise good condition might be rebuilt with new seals at low cost, or if no seal kits are available,  there are many options for a new replacement.

Cheers,
Red

[simi_ed]

It could be the pistons have pushed back into the bore, if you had a steering bump and caused a rotor wobble.  If it pumped back up, that was probably the problem.  Otherwise, I'd guess MC, as others have.

My 2¢