Is the problem one of a faulty batch that QA has picked up or simply poor initial selection and limited development/testing? If the design is ok but faulty seals, manufacturing shortcomings then two options. Ditch the supplier. Get tighter QA in place with the supplier. A third option is to have more than one supplier. Problems with one are covered by the second ( third even). I guess that selecting parts for a car of known weight/ performance is fairly straight forward for stopping capability with space available to fit a second factor. My plus8 had Austin Princess callipers. Off the shelf and suitable. Rocket science not needed.
