Re: wheel shake
My guess is suspension. An imbalanaced wheel would vibrate as you pass through a speed range whether accelerating or braking. Warped discs would more likely cause a vibrabtion in the brake pedal rather than a steering issue.
Track rod end and wishbones become tensioned under braking so any wear or play will show up. TRE is my chief suspect of the two.
Warped discs don't usually cause a vibration in the brake pedal, because the brake pads are moved in opposite directions by the deformity in the disc, resulting in very little change in system pressure. The reason it's always most noticeable in the steering is that when the disc is warped, using the brakes means that the pads will try to force the disc to run straight. The vibration from this is more severe the further you get from the axis of rotation, so it's transmitted into the wheel and from there into the steering, where of course there's a direct mechanical link to your hands.
The reason I know this is that my front n/s caliper seized a little while ago, overheating and warping the disc. After that I suffered the same problem - vibrating steering wheel when braking from motorway speeds. New discs+pads solved it. I can discount the track rod ends as mine are new.
Hope that's helpful
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