It doesn’t hurt to bring these topics to the fore occasionally, as I feel that they are often seen as basic issues & not worthy of further thought. The subject of brake judder is an interesting one & it is possibly not as straightforward as many technicians may first assume.
I recall a few years ago a similar problem to which this thread is devoted. The old Ford Sierra (Sapphire in my experience), had a problem with repeated brake judder & my local dealer was inundated with warranty claims.
It was the same pattern as seen here, where new discs seemed to cure the brake judder for a few weeks, but eventually the problem would return. The dealer workshop would eventually insist on replacement bearings & flanges, before honouring any repeated warrantee claims. Their explanation was that the judder was caused by a variable thickness of the brake disc & not a warped disc.
When new discs are fitted, they are of uniform dimensions. The problem is that when discs aren’t mounted onto a “true” surface, they will wear on the high spots during brake application. The high spots are worn away & before long you end up with two thin sections on your brake disc.
It is quite hard to put across in words alone & I can’t draw circles