( CNN ) -- During a NASCAR race , drivers do hundreds of laps at speeds of more than 300 kilometers per hour . But the seconds spent during a pit stop -- changing tires and refueling the car -- may be the most crucial moments of any race . Greg Morin is head coach of the 48 pit crew at Hendrick Motorsports , the team that helped one of NASCAR 's most successful drivers , Jimmie Johnson , win six championships . `` It is safe to say that if you do n't have a well performing pit crew that executes well on pit road , you are going to affect the overall outcome of the race in a potentially hugely negative manner , '' says Morin . He adds : `` Our goal is to hit a 12-second pit stop , hit five lug nuts off , five lug nuts on ( on each wheel ) ... get it full of fuel and ship it down pit road . '' Watch the video above to see the Hendrick Motor Sports ' 48 pit crew in action .
NASCAR pit crews are key to a driver 's success . Crews have to make the stop inside 30 seconds . Head coach of the 48 car crew at Hendrick Motorsports explains the importance of pit crew .