PA24 THROTTLE CABLE MALFUNCTION CAUSES RWY EXCURSION.

Narrative

I WAS TAKING OFF USING RWY 29 AT SBP FOR A FLT TO WHP WITH NORMAL INST INDICATIONS. I ROTATED AT 85 MPH AND THINGS AT THAT POINT DIDN'T FEEL OR SOUND RIGHT. I ABORTED THE TKOF AND RAN OFF THE END OF THE RWY ON TO THE GRASS. I EXECUTED THE SHUTDOWN PROC AND WE EXITED THE ACFT. THERE WAS NO DAMAGE TO THE ARPT; ACFT; OR INJURY TO PERSONS ON BOARD. A SUBSEQUENT EXAMINATION OF THE ACFT AT SBP REVEALED THAT THE FRICTION NUT ON THE THROTTLE CABLE HAD COMPLETELY BACKED OUT AND COME OFF ITS NORMAL SCREW MOUNTING. THIS SIT REDUCED THROTTLE TRAVEL SLIGHTLY AND I BELIEVE WAS THE CAUSE OF THE LESS THAN MAX TKOF PWR SIT. THE ENTIRE LENGTH OF RWY 29 WAS NOT AVAILABLE FOR USE DUE TO CONSTRUCTION AT ITS S END. THE PURPOSE OF THE CONSTRUCTION IS TO EXTEND THE LENGTH OF RWY 29. TO USE THE MAX RWY AVAILABLE DURING CONSTRUCTION REQUIRED BACK TAXI FROM TXWY G APPROX 500 TO 1000 FT WHICH MOST PRIVATE ACFT PLTS CHOOSE NOT TO DO. WHEN CONSTRUCTION IS PROLONGED; AS THIS ONE HAS BEEN; I WOULD SUGGEST THAT A TEMPORARY TXWY ENTRY BE BUILT AT THE MOST AVAILABLE RWY POINT. TO REDUCE CONSTRUCTION COSTS THE TEMPORARY TXWY ENTRY COULD HAVE ACFT WEIGHT LIMITS SUCH THAT THE MAJORITY OF ACFT WOULD HAVE ACCESS. THIS WOULD ENHANCE SAFETY BY ELIMINATING THE NEED TO BACK TAXI ON RWY 29; ELIMINATING THE TEMPTATION FOR AN INTXN TKOF; AND INCREASING THE TIME TO REACT TO ANY UNANTICIPATED ACFT CIRCUMSTANCES.