HPI clutch springs are constructed of red steel. Stronger spring than stock clutch setup. Are you looking for more punch from your Baja 5B? Then take a look at this. Our 8000 RPM Clutch Spring for the Baja 5B allows the engine to rev to a higher RPM before the clutch engages, delivering more punch and higher engine response off the line. The 8000 RPM Clutch Spring is a direct replacement for the stock clutch spring in your Baja 5B and comes standard with the High Response Clutch Shoe and Spring Set. Pick up an HPI Racing 8000 RPM Clutch Spring and put the pedal to the metal! When using the 15449 clutch spring with standard Baja 5b clutch shoes, engagement starts at 7000 RPM and is fully engaged at 8000 RPM. Required Parts Installation