jakes

have had classic MY 99 for 3 yrs..occasionally when starting, started motor grinding on ring gear, car initially had warranty,dealers changed starter. problem sorted for 6 months then recurred endud up with damaged ring gear had to change flywheel and starter.now happening again. ? is this a common problem as brother has had same probs on his MY 99 also. any ideas to stop this happening. all connections fine.