anyone having issues with the front brake?

randomly the lever will one minute act as if it is working where it has been adjusted to and then the next minute the lever acts like it has been adjusted further in towards the bars

the disc is perfect straight

fluid level is full

everything seems to be normal

 

 You need a new rebuild kit. I would clean up the bore first. Otherwise throw that m/c away and find an AJP.

Mine did exactly the same thing ('15 Sherco 300). I never really dug into it to figure it out, but yup... exactly as you describe. Bled it a few times, no change.

 

I have a hard time believing it needed a rebuild... especially since it did it from brand new.

Edited October 20, 201510 yr by heffergm

 Not hard believing it, pull out the piston and look at the seal lips. PS it`s not just Sherco, all the new bikes with these crap hydraulics.

Edited October 20, 201510 yr by lineaway

That I can't argue with... my Beta master cylinder leaked from the off.

 

If they're like this from new though, what's the point of a rebuild kit? Presumably it's made with exactly the same crap components, so I wouldn't expect it to solve anything.

Edited October 20, 201510 yr by heffergm

Have a hard time with actually reading? There is nothing wrong with the seal, it`s the bore and poor quality of finishing the product that ruins the piston cup seal from the get go. 

Awesome comment. Cheers for that. Spero che hai una buona sera.

Overhauled mine with a new seal kit and piston 2 weeks ago, the bike has 8 months regular use. I was unable to see any wear or damage on the originals and no sharp edges on the cylinder ports. I don't hold out much hope of long lasting success.

It would be different scenario if these were new cars etc.

Edited October 21, 201510 yr by sirdabalot

Oh, the joys of reliable hydraulics!

Two usual causes.

1) Machining crap left in after manufacture, this is fine sharp swarf and it cuts the seals or wedges in the lips causing leakage. Usually  a good flush out and a seal change cures this.

2) A poor finish on the cylinder bores and sharp edges / protruding burrs on the fluid ports. Careful work with de burring tools the lapping out the bores with 1200 or 1500 grade wet and dry, then fitting new seals usually cures this.

might be as a simple as time for a pad change.

Bring back ajp well made and only broke when you dropped the thing on its head!Thats probably why they went bust,too well made!

I've seen people using hope mtb levers.are these any good?

The bike did this when I first purchased it July 2015.  The pads are near new.

 

Last week I purchased a Master cylinder rebuild kit and installed it.  The old piston and seals looked great.  Nothing visible in the bore, but still cleaned it up as best as possible.  New piston was different than original.  Bled the brakes and I still have the problem.  Sometimes the lever is where it is adjusted to and sometimes the lever actuates closer to the grip.  Seems to be happening after a big zap or bouncing down hill.

 

Any other ideas?

Interesting observation... I hadn't really equated the two, but now that you mention it, it was always after a downhill run that I noticed it on mine as well.

Are your wheel bearings ok, sometimes if there is play in the bearings the disk will push the pads back further and the cause you to have a different position on the lever until you pump the lever and then it returns to the original position!