Note: The rear radius arms can get bent slightly. eg. if they impact a kerb or after a heavy sideways force/impact.
(Maybe compare if equal distances between rear subframe and the radius arm / shock absorber as a reference point on each side of the car).
Also check for wear/play in the rear radius arm pivot/bearings due to lack of greasing. Jack up and check for sideways movement of the arm.
For small precise adjustments, you can buy adjustable brackets for the rear subframe which replace the standard fixed outer brackets bolted to the subframe which locate the radius arms.
Minispares sell some (see link below) which are adjustable for both camber and toe-in.... however a Mini as standard factory set up has toe in at the rear, so you can just use suitable thickness shims/spacers between the radius arm outer brackets and the subframe to adjust toe-in without the need for buying the dual adjustable brackets.
CAMBER AND TOE REAR TRACK ADJUSTMENT BRACKETS MS73EVO
https://www.minispar...stment-brackets
Edited by mab01uk, Today, 08:21 AM.