Preheat oven to 325°. Place ham, cut side down, on rack in large roasting pan. Pour 2 cans cola and squeeze juice from orange into pan. Add orange halves and thyme sprigs to pan. Bake ham 1 hour or until internal temperature reaches 90°.
Meanwhile, in small saucepot, heat remaining can of cola over medium-low heat 30 minutes or until reduced by half. Stir remaining ingredients into saucepot and simmer 3 to 5 minutes, or until brown sugar dissolves; remove from heat.
Remove ham from oven. With sharp knife, lightly score outside of ham, making parallel 1/2-inch-deep incisions in crosshatch pattern. Brush ham with some of the glaze and return ham to oven. Bake 45 minutes longer or until internal temperature reaches 130&