JAG IRS brake shudder

[ollykiwi3]

time for an update:
i jacked up the car and ran it in gear to see what was going on. the LH disc was wobbling a little. I took the disc off and clocked it up in a lathe and it was only .001" out, so minimal. I found a burr on the stab axle flange and a corresponding imprint on the disc mount face. cleaned up the burr and remounted disc. problem solved.....no. did the run out check and it was still up to .015" out. still didnt think that was too bad.
pulled the stub axle off, took it and the disc to work and clocked them both up on lathe. nothing really to write about. checked the flange for run out, and was ok but skimmed it anyway just to be sure.
bolted them together on lathe and again checked run out. only couple thou. again minimal.
put it all back together and checked run out on car, again around .004" consider this minimal.
finally had some good weather yesterday and went for drive thining it was all good..not so. bloody shudder still there.
again, its only at light pedal pressure just as your rolling to a stop. wheels are barely turning.
my next step is to swap pads and pins over. Im going back to my original gut feeling that the pins are worn or the caliper slot for the pads is worn out. i cant hear it clunk as you apply brake,meaning the pads arent jumpimg forward, but maybe its not worn that bad yet, but bad enough to get a harmonic vibe going with a little pedal on and its gripping and letting go again in a high frequency.
will have a go at jacking up again and running it to see what the disc run out looks like also.
any more ideas?