Clav, how many miles are on the caliper? I presume that you have the J55 brake set up? If for some reason you don't, make sure that you have the correct pin. Some of the replacement pins have two grooves to allow them to be used in both the standard and J55 setup. Another possibility, without having the benefit of actually seeing the caliper is the wear factor. If for some reason the aluminum housing on the caliper is worn or in some way out of spec, that could create some slop and allow for some travel that could put some weird stress on that "E" clip. Re-check (again) your installation, and let us know wht you find.