The rear brakes on my '97 850 N/A squeal when applied at low speeds, i.e. just before the car comes to a stop, or when rolling along in stop-and-go traffic. The brakes were done by a non-Volvo shop so in all likelyhood no shims are installed.

I noticed there are three types of shims: the solid square, the square with a small window cut out in the center, and the ones with a large cutout on one side. Which type should I use, in combination with which pads? Bay 13 makes reference to different shims, but I am still confused, plus they don't talk about the center cutouts at all.

Could someone please advise on a suitable shim/pad combination for a basic
brake job? I don't need anything high-performance. Also, will it be necessary to get new pins and springs?

Thanks in advance.
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'97 850 n/a Wagon, 120K mi