I had a steering wheel vibration under braking that became rapidly worse over the last 5000 miles or so, to the point that moderate braking from freeway speeds became an alarming experience. I know this problem has been encountered by many others, and there are a lot of threads on it, but I haven't previously seen the solution that I discovered.

Having replaced the front rotors and pads quite recently, my initial suspicion fell on the brakes themselves. I removed both front calipers and checked the pad and rotor surfaces for any anomalies and found nothing - no cracks, normal even wear. I checked runout of both inner and outer surfaces and found everything 0.001" or less. As a result of a friend's suggestion that it could be suspension related, I suddenly realized while looking at the suspension that the torque under braking tries to rotate the suspension in such a way that caster is lessened. The Saab doesn't have much to begin with - 3 degrees - so I began to wonder if the vibration didn't have anything to do with the brakes themselves, but was due to a sloppy suspension mount allowing the caster to reduce to the point that the front wheels become unstable. Easy enough to test this one. So I torqued all the suspension fasteners (there are a lot of them!) to spec, and test drove. Problem solved!

2009 Saab 9-3 wagon, 79K miles