A machine comprising: an outer member; an inner member mounted for rotation about an axis relative to the outer member; and a seal system comprising: a seal housing mounted to the outer member; one or more seal rings held by the seal housing and having an inner diameter surface ; and a seal runner mounted to the inner member and having a first outer diameter surface portion contacting or facing the inner diameter surface of the one or more seal rings , wherein: the seal runner has a circumferential array of mounting features ; and one or more weights are mounted to one or more of the mounting features ; wherein the seal runner has: a mounting section mounted to the inner member; a sealing section including the first outer diameter surface portion radially outwardly spaced from the mounting section ; a first hub between the mounting section and the sealing section , wherein the first hub is an aft hub extending from near an aft end of the mounting section radially outwardly and forwardly to merge with a forward end portion of the sealing section so as to leave the remainder of the sealing section axially cantilevered aftward to a free distal aft end ; a balancing section including the mounting features ; and a second hub between the mounting section and the balancing section , the second hub extending radially outwardly and forwardly to merge with an aft end of the balancing section , wherein the mounting section , the sealing section , the first hub , the balancing section , and the second hub are formed on a single metallic piece, and wherein the one or more seal rings are carbon seal rings. an outer member; an inner member mounted for rotation about an axis relative to the outer member; and a seal system comprising: a seal housing mounted to the outer member; one or more seal rings held by the seal housing and having an inner diameter surface ; and a seal runner mounted to the inner member and having a first outer diameter surface portion contacting or facing the inner diameter surface of the one or more seal rings , a seal housing mounted to the outer member; one or more seal rings held by the seal housing and having an inner diameter surface ; and a seal runner mounted to the inner member and having a first outer diameter surface portion contacting or facing the inner diameter surface of the one or more seal rings , the seal runner has a circumferential array of mounting features ; and one or more weights are mounted to one or more of the mounting features ; a mounting section mounted to the inner member; a sealing section including the first outer diameter surface portion radially outwardly spaced from the mounting section ; a first hub between the mounting section and the sealing section , wherein the first hub is an aft hub extending from near an aft end of the mounting section radially outwardly and forwardly to merge with a forward end portion of the sealing section so as to leave the remainder of the sealing section axially cantilevered aftward to a free distal aft end ; a balancing section including the mounting features ; and a second hub between the mounting section and the balancing section , the second hub extending radially outwardly and forwardly to merge with an aft end of the balancing section , wherein the mounting section , the sealing section , the first hub , the balancing section , and the second hub are formed on a single metallic piece, and wherein the one or more seal rings are carbon seal rings. <EOS>