On lap 318 Pierre Kaffer brought the GTLM class-leading #62 Risi Ferrari in after only 15 laps. An engineer brought out a laptop and attempted to divine the nature of the problem, which after —the car started up and took off. The team manager said only that the engine had lost power.
The team installed a new ECU, but the problems persisted and a couple of laps later the car pitted and went behind the wall.
This left Ryan Briscoe in the #3 Corvette with the GTLM lead, ahead of Wolf Henzler in the #17 Falken Tire Porsche and Simon Pagenaud in the #4 Corvette.
The battle in GTLM was somewhat muted temporarily by the loss of the Risi Ferrari, but the fight in GTD made up for it, with Rene Rast in the #48 Miller Racing Audi R8 chased the #33 Riley Viper driven by Jeroen Bleekemolen. The Viper had an excess of power; the Audi had much better brakes. For the first several laps of the battle, power was triumphant. Then the lapped #73 Park Place GTD Porsche got between the two GTD leaders, giving Bleekemolen a slight margin.
Finally, after ten laps, Rene Rast managed to fight his way past Bleekemolen, taking the GTD lead on lap 330.
On lap 326 Jordan Taylor used a bit of racecraft to take the overall lead. Taylor in the #10 WTR Dallara-Corvette pitted a lap ahead of Kyle Larson in the #01 Ganassi Riley-Ford Ecoboost.
While Larson struggled to warm his tires, Taylor made his charge, his tires already having a lap of heat in them. Larson’s Riley-Ford squirmed while Taylor’s Dallara-Corvette was firmly planted; Larson could not hold off the charging Jordan Taylor.
On lap 347, at 11 hours, 11 minutes, the race’s ninth yellow flag waved.
When it did, Jordan Taylor in the #10 WTR Dallara-Corvette held a rapidly shrinking lead over Kyle Larson in the #02 Ganassi Riley-Ford EcoBoost, which was a lap of ahead of team car #01 with Scott Pruett at the wheel. Fourth came AJ Allmedinger, who turned in the fastest lap of the race at 1:39.724 on lap 340.
In GTLM, Ryan Briscoe led in the #3 Chevrolet Corvette C7.R led a pair of Porsches, Marc Lieb in the #911 and Earl Bamber in the #912 (which had made up a five-lap deficit incurred when its alternator failed early in the race.) Simon Pagenaud, in his first drive in a GT car, came fourth in the #4 Corvette.
The Porsches were circulating nose to tail—just a bit too close. The 911 and the #007 Aston Martin of Christoffer Nygaard bounced off the curb and collided entering Turn One. Bamber in the #912 stomped on the brakes but couldn’t slow; he slammed the already injured #911’s left rear corner. Bamber punctured a right front tire which destroyed the front bodywork and tore up the suspension; Lieb suffered a severely damaged left rear. In an instant, Porsche lost its chance to repeat its 2014 triumph in GTLM.
John Bennett retained the PC lead in the Core Autosport Oreca, Rene Rast in the #48 Miller Racing Audi R8 LMS led GTD.