On my TD, rear brake squeal has always been a problem despite squeaky clean calipers.
Today I replaced the rear discs on the TD (they were well worn) and I spotted it has no anti-squel shims fitted.
Should they be there? I've not seem them mentioned before and pad kits don't seem to include them. Interestingly, pr.net makes no mention of them for either the XANTIA I or II but do list them for the C5 which appears to use a very similar (identical?) caliper. Maybe my Activa had C5 pads fitted
My Activa has always had very quiet rear brakes, even when the calipers were bady corroded and the pads were worn wedge-shaped.
These shims may just be a cure for a persistent squeal.