When their friends were listening to the Beatles or Led Zeppelin in the 1970s, Jim and John Harbaugh were listening to Bob Ufer–even after their mom, Jackie, told them to turn it off and go to bed.

That’s one of the intimate details in Overtime, John U. Bacon’s new book. Bacon follows the Wolverines through last year’s football season, painting vivid portraits of everything from the team’s workouts to its video crew. But the book is also a mutigenerational portrait of the Harbaughs.

“At the center of their family life,” Bacon writes, “was football.”

Jim Harbaugh was paid $7.5 million last year. But “you can’t say that any one of these guys got into coaching for the money,” Bacon says in a phone interview. As he points out in the book, when Jim’s father, Jack, was a U-M assistant coach from 1973 to 1979, the family “could afford only one car, a yellow Dodge station wagon. Many days Jackie would drive Jack to the football building early in the morning then drop the kids off at St. Francis Elementary … The Harbaughs may have lacked a big house, fancy cars, or fame, but they all remember their years in Ann Arbor as their happiest.”

Bacon grew up in Ann Arbor, too, but he says his childhood was nowhere near the “alpha A-plus environment” of the Harbaughs–and “none of us were that talented. ” But he allows that his own life experience may have helped him empathize with theirs: his previous Michigan football book, Endzone, “came out a few weeks before Teddy,” Bacon’s now four-year-old son.