it seems people change pads and get no shudder for a while or machine discs and also no shudder for some time,all your really doing is taking your brakes appart, lossening .the callipers a bit and this is why it goes away for a while.Try to unbolt the callipers and remove the pads,then use high temp waterproof grease on the sliders,carfull not to get grease on ya discs or pads