robsbird,the other racers have explained it real good I would ad a couple things to help one is drive your car in the pits around 2000rpm in low gear and smash the gas and see where the tack goes before the car moves this is your flash,if staging to high you've loaded the chassie and with out some flash it wont transfer the wight.If go to a trans break you control the launch and rule of thum is you want be 1000 or 1500rpm less than or advertised setting.