"He was a horse whisperer with racehorses," fellow trainer Barry Abrams said.
Born July 9, 1941, in New York, Frankel was the son of New York caterers. He grew up in Brooklyn and was a maverick teenager who loved racing, handicapping and gambling.
He started training in 1966 in New York, moved to California in 1972 and was known as the "King of the Claimers" for his ability to select horses before a race to purchase regardless of the outcome.
"He was very smart," trainer Julio Canani said. "He'd claim a horse for $20,000 and run him for $8,000. He had everyone confused. They didn't know what he was doing."
Frankel's horses won a record 60 times during the Hollywood Park spring meeting in 1972, one of 10 training titles he won at the Inglewood track.
He started turning claimers into stakes winners, and by the 1980s and '90s, he was attracting top owners, such as Juddmonte Farm's Prince Khalid Abdullah, a Saudi owner who became a loyal supporter.
"In my eyes, he and Charlie Whittingham were the benchmarks," trainer Ron Ellis said. "I guarantee there wasn't anybody who claimed as many horses and made them stakes winners. He moved everything up that he got his hands on."
Frankel was brash and opinionated, qualities that Dodgers Manager Joe Torre came to admire. The two built a friendship on and off the racetrack. Torre was a part-owner with Frankel of the top horse Vineyard Haven, who was sold last year as a 2-year-old for a lucrative price. Torre watched the recent Breeders' Cup from Frankel's box at Santa Anita and was one of the few people to have visited with him last week.
"I was very touched with our last conversation," Torre said. "He's been a dear friend. He's going to be missed. He was a very private person, but there's an enormous importance what his relationship meant to me."
Frankel used to attend New York Yankees games when Torre was their manager, then attended games at Dodger Stadium.
"He was always critical," Torre said. "His comments were always blunt, but I loved listening."
It was around the barn, on the track or hanging out with his horses where Frankel was at ease.
"He could communicate with a horse better than he could with humans," Abrams said. "He felt what a horse felt. He could tell when a horse could run his best race. He was an amazing human being when it came to animals."
In 2003, Frankel's horses won a single-season record 25 Grade I races, including Empire Maker in the Belmont Stakes. He won six Breeders' Cup races, including with Ghostzapper in the 2004 Breeders' Cup Classic. He saddled the winners of 28 races worth $1 million or more. He's the all-time leader with 952 wins at Hollywood Park and 917 victories at Santa Anita, and his horses won 3,654 races overall.
"The thing I'll remember is that he has help in his barn that have been there for 20, 25 and 30 years," said Ron Anderson, the agent for jockey Garrett Gomez. "You don't have that in any business anymore. He employed grooms for dozens and dozens of years because he was so kind and thoughtful. He also came off as a hard, brazen type, but the biggest secret in horse racing was how soft and warm he was."
Humberto Ascanio, an assistant trainer to Frankel for more than 30 years, had been running Frankel's Southern California stable for the last six months in his absence. Ascanio would communicate with Frankel daily by phone.
"He was a tough man," Ascanio said. "He wanted everything to go right. He was tough all the way to the end."
Frankel was being treated at Cedars-Sinai Medical Center in Los Angeles until he was sent home Saturday.
Frankel, who was inducted into the Southern California Jewish Sports Hall of Fame in 2004, is survived by a daughter, Bethenny.
A memorial service is scheduled for today at 3 p.m. at Hillside Memorial Park, 6001 Centinela Ave., Los Angeles.
Times staff writer T.J. Simers contributed to this report.