Following his retirement, Brabham and his family moved to a farm between Sydney and Melbourne.
Brabham says that he "never really wanted" the move, but his wife hoped their sons could grow up away from motorsport.
As well as running the new venture, he continued his interest in businesses in the UK and Australia, including a small aviation company and garages and car dealerships.
He also set up Engine Developments Ltd. in 1971 with John Judd, who had worked for Brabham on the Repco engine project in the mid 1960s.
The company builds engines for racing applications.
Brabham was also a shareholder in Jack Brabham Engines Pty Ltd., an Australian company marketing Jack Brabham memorabilia.

The Brabham team continued in Formula One, winning two further Drivers' Championships in the early 1980s under Bernie Ecclestone's ownership.
Although the original organisation went into administration in 1992, the name was attached to a German company selling cars and accessories in 2008, and an unsuccessful attempt to set up a new Formula One team the following year.
On both occasions the Brabham family, which was unconnected to the ventures, announced its intention to take legal advice.
In September 2014, Brabham's youngest son David announced Project Brabham, a new team planning to use a crowdsourcing business model to enter the 2015 FIA World Endurance Championship in the LMP2 category.

Despite his three titles, and although John Cooper considered him "the greatest", Formula One journalist Adam Cooper wrote in 1999 that Brabham is never listed among the Top 10 of all time, noting that "Stirling Moss and Jim Clark dominated the headlines when Jack was racing, and they still do".
Brabham was the first post-war racing driver to be knighted when he received the honour in 1978 for services to motorsport.
He has received several other honours and in 2011, the suburb of Brabham in Perth, Western Australia, was named after him.
A race circuit and an automotive training school were also named after him in the early 2010s.

In retirement, Brabham continued to be involved in motorsport events, appearing at contemporary and historic motorsport events around the world where he often drove his former Cooper and Brabham cars until the early 2000s.
In 1999, after competing at the Goodwood Revival at the age of 73 he commented that driving stopped him getting old.
Despite a large accident at the 2000 Revival, the first racing accident to put him in hospital overnight, he continued to drive until at least 2004.
By the late 2000s, ill-health was preventing him from driving in competition.
In addition to the deafness caused by years of motor racing without adequate ear protection, his eyesight was reduced due to macular degeneration and he had kidney disease for which by 2009 he was receiving dialysis three times a week.
Nonetheless, that year he attended a celebration of the 50th anniversary of his first world championship at the Phillip Island Classic festival of motorsport, and in 2010 flew to Bahrain with most of the other Formula One world Drivers' Champions for a celebration of 60 years of the Formula One world championship.
Brabham was the oldest surviving F1 champion.

Brabham and Betty had three sons together: Geoff, Gary, and David.
All three became involved in motorsport, with support from Brabham in their early years.
Between them, they have won sportscar and single-seater races and championships.
Geoff was an Indycar and sportscar racer who won five North American sportscar championships as well as the 24 Hours of Le Mans, while David competed in Formula One for the Brabham team and has also won the Le Mans race as well as three Japanese and North American sportscar titles.
Gary also drove briefly in Formula One, although his F1 career consisted of two DNPQ's for the Life team.
Brabham and Betty divorced in 1994 after 43 years.
Brabham married his second wife, Margaret in 1995 and they lived on the Gold Coast, Queensland.
Brabham's grandson Matthew (son of Geoff) graduated from karts in 2010 and won two ladders of the Mazda Road to Indy, event
Following his retirement, Brabham and his family moved to a farm between Sydney and Melbourne. Brabham says that he "never really wanted" the move, but his wife hoped their sons could grow up away from motorsport. As well as running the new venture, he continued his interest in businesses in the UK and Australia, including a small aviation company and garages and car dealerships. He also set up Engine Developments Ltd. in 1971 with John Judd, who had worked for Brabham on the Repco engine project in the mid 1960s. The company builds engines for racing applications. Brabham was also a shareholder in Jack Brabham Engines Pty Ltd., an Australian company marketing Jack Brabham memorabilia.
The Brabham team continued in Formula One, winning two further Drivers' Championships in the early 1980s under Bernie Ecclestone's ownership. Although the original organisation went into administration in 1992, the name was attached to a German company selling cars and accessories in 2008, and an unsuccessful attempt to set up a new Formula One team the following year. On both occasions the Brabham family, which was unconnected to the ventures, announced its intention to take legal advice. In September 2014, Brabham's youngest son David announced Project Brabham, a new team planning to use a crowdsourcing business model to enter the 2015 FIA World Endurance Championship in the LMP2 category.
Despite his three titles, and although John Cooper considered him "the greatest", Formula One journalist Adam Cooper wrote in 1999 that Brabham is never listed among the Top 10 of all time, noting that "Stirling Moss and Jim Clark dominated the headlines when Jack was racing, and they still do". Brabham was the first post-war racing driver to be knighted when he received the honour in 1978 for services to motorsport. He has received several other honours and in 2011, the suburb of Brabham in Perth, Western Australia, was named after him. A race circuit and an automotive training school were also named after him in the early 2010s.
In retirement, Brabham continued to be involved in motorsport events, appearing at contemporary and historic motorsport events around the world where he often drove his former Cooper and Brabham cars until the early 2000s. In 1999, after competing at the Goodwood Revival at the age of 73 he commented that driving stopped him getting old. Despite a large accident at the 2000 Revival, the first racing accident to put him in hospital overnight, he continued to drive until at least 2004. By the late 2000s, ill-health was preventing him from driving in competition. In addition to the deafness caused by years of motor racing without adequate ear protection, his eyesight was reduced due to macular degeneration and he had kidney disease for which by 2009 he was receiving dialysis three times a week. Nonetheless, that year he attended a celebration of the 50th anniversary of his first world championship at the Phillip Island Classic festival of motorsport, and in 2010 flew to Bahrain with most of the other Formula One world Drivers' Champions for a celebration of 60 years of the Formula One world championship. Brabham was the oldest surviving F1 champion.
Brabham and Betty had three sons together: Geoff, Gary, and David. All three became involved in motorsport, with support from Brabham in their early years. Between them, they have won sportscar and single-seater races and championships. Geoff was an Indycar and sportscar racer who won five North American sportscar championships as well as the 24 Hours of Le Mans, while David competed in Formula One for the Brabham team and has also won the Le Mans race as well as three Japanese and North American sportscar titles. Gary also drove briefly in Formula One, although his F1 career consisted of two DNPQ's for the Life team. Brabham and Betty divorced in 1994 after 43 years. Brabham married his second wife, Margaret in 1995 and they lived on the Gold Coast, Queensland. Brabham's grandson Matthew (son of Geoff) graduated from karts in 2010 and won two ladders of the Mazda Road to Indy, event
Jack Brabham