Updated MAR 30, 2015 1:26p ET  Dale Earnhardt Jr. entered Sunday's STP 500 as the most recent winner at Martinsville Speedway and was eager to win his second grandfather clock trophy. Those lofty hopes, however, were dashed when a wreck on Lap 227 sent him behind the wall.  The incident, which occurred going into Turn 1, started when Casey Mears was spun in the middle of the corner and the rest of the field stacked up behind him. Running in the back of the pack, Earnhardt could not get slowed up and drove hard into the back of Paul Menard's No. 27 Richard Childress Racing Chevrolet.  "There was just a lot of checking up getting into (Turn) 1," Earnhardt said as his crew thrashed on his car in the garage. "Somebody must have got turned sideways. They all stopped pretty hard getting into the corner. It happens here. We were in the back of it and couldn't get slowed down. Knocked the radiator out of it. It happens getting in the back there and getting in all that traffic. It's good fun racing, though.  While this incident sent Earnhardt's No. 88 Hendrick Motorsports Chevrolet behind the wall, it was hardly his first issue of the day. Starting in the 14th spot, Earnhardt struggled with a significant vibration in the drivetrain that eventually broke the shifter inside the car.  The team made multiple pit stops throughout the race in an attempt to fix the issue, and changed the shifter lever three times before the Lap 227 incident sent the team behind the wall.  "My car was really, really good, except we had a real, real bad vibration in the drivetrain that kept breaking the shifters off right on top of the transmission," he said. "It was vibrating real bad and that shifter is like a tuning fork and just snaps it right there at the transmission, so there's nothing there for me to use. We finally put a third shifter on it that was unlike anything else that was in the car. I don't know whether that was going to last the rest of the day."  With the shifter issues miring Earnhardt deep in the field, Earnhardt said the wreck was simply "bad luck" racing at the back of the pack.  "You've got to be doing it right and there's a lot of wrecks back there. It bit us today," he said. "I'm not going to second-guess what we're doing, and I feel like our team is strong, we won't have any problems coming back."  When the race restarted, Earnhardt remained behind the wall and in the 39th spot. The team was able to replace the radiator, removed the hood, front sheet metal and sent him back on track on Lap 276. But by then he was 47 laps down to the race leaders.  Logging laps with a heavily damaged car, Earnhardt finished Sunday's race in the 36th spot as Joe Gibbs Racing's Denny Hamlin earned his first victory of the season.  VIDEO: Dale Earnhardt Jr.'s No. 88 Hendrick Motorsports Chevrolet takes on heavy damage in incident
Dale Earnhardt Jr.'s difficult day in the STP 500 at Martinsville Speedway goes from bad to worse when he's involved in multi-car accident. His hopes for winning a second grandfather clock are dashed.