I would advise all IRS owners to inspect their car's rear trailing
arms for cracking, as a breakage here could ruin your whole day. During an examination
of my car's rear suspension about a year after the diff mounts were fixed I noticed
25+mm cracks in both trailing arms. These cracks were in the outermost web of metal
connecting the mass of the arm to the cylindical section containing the hub mounting.
This is viewed most easily with the car on a ramp, the web runs longditudinally with
respect to the car, and is adjacent to the brake back-plate. Check carefully for cracks
here. I replaced both arms with ones from a scrapped 4A.