CV joint breakage-in a nutshell.

When the side of a cv joint gets ripped apart or torn from the drive shaft it is usually when the car is on full lock where suspension stability has been lost. This phenomenon usually happens when a car is on full lock when it hits a ditch or mound on entry or when being pulled out on full lock, or more usually where the car is sliding around such as in Rallying, Rallycross and Autocross.

One of the main reasons for this to happen is if you do not have collars or not running lock stops on the steering rack, the driveshaft can be forced sideways in the CV joint, trying to break its way out.

Inexperienced car preparation for such events as mentioned is often overlooked as this only happens under severe or certain conditions but is widely known by participants competing in arduous events from experience or trained rally mechanics. This issue is highlighted more when large diameter driveshafts or larger Allegro/Maxi cv joint are used.

Most original works cars had Mk1 racks which were a ¼ less turn each way on lock and later rally cars or any using later Mk2 racks fitted stops. Rover were aware of this fact and fitted stops (collars) to the MPI cars with 13” wheels to alleviate damage such as hitting the inner wings.