Larry Grant, a 49ers backup linebacker the past two seasons, has been suspended the first four games of next season for violating the league's policy on performance-enhancing substance, the NFL announced Friday. Grant, a five-year veteran, is an unrestricted free agent, and he remains eligible to participate in all offseason and exhibition-season actions upon joining a team. As Patrick Willis' backup the past two seasons, Grant might best be known for forcing a fumble that secured a December 2011 win at Seattle. Grant also was a key member of the special teams, totaling 16 tackles since 2011. Last month, the 49ers signed Grant's potential replacement in former Bengals linebacker Dan Skuta.