Mystery rear disc brake problem.

[Andy in Germany]

Just the alcohol will do fine on the disc. Contaminated pads may be saveable if not too bad. Clean with alcohol, lightly sand the surface then do with alcohol again and should be okay.

I'm guessing you can't see the contamination? This would explain why changing pads (and everything else apart from discs) didn't help.

 

[Jody]

I'm guessing you can't see the contamination? This would explain why changing pads (and everything else apart from discs) didn't help.

No you can't see it and it takes very little oil to contaminate the brakes. I've managed to burn slight contamination from discs/pads by getting the brakes really hot.

 

[T4tomo]

Its unclear whether squeezing the lever is moving the pads and hence its a disc / friction / contamination issue, or....
squeezing the lever isn't moving the pads and hence its a lever/piston/ fluid line / set up with the new SLX's issue.

hydraulic discs are generally zero hassle and easy to maintain, but when you get an issue an absolute pig to sort out !

 

[Andy in Germany]

Its unclear whether squeezing the lever is moving the pads and hence its a disc / friction / contamination issue, or....
squeezing the lever isn't moving the pads and hence its a lever/piston/ fluid line / set up with the new SLX's issue.

hydraulic discs are generally zero hassle and easy to maintain, but when you get an issue an absolute pig to sort out !

As far as I know everything is moving just fine, so I think the contamination may be the point. The problem is exactly the same as with the previous setup and the only thing that hasn't been checked/adjusted/changed is the disc.

 

[fossyant]

I assume they aren't 'stopping' the bike well - being rear won't anyway, but if they aren't biting well, then contamination. I've had this on MrsF's BMC with SLX - usually the front. Just stop's stopping when it's been sat - also an issue is the brakes are never used 'hard' as the bike isn't used much. I tend to clean the rotor and sand the pad every so often, but if the pads get contaminated, you've generally got to bin them.