Sherwood Dubose's cell phone is vibrating.

He picks it up. One message, no, two, three . . . six.

''Please stop!'' he cries in mock horror.

The unending text messages are from his business partner, William S. Stevens III, who is in South Africa. Text-messaging, frequent trips to Capetown and Johannesburg, long-distance phone calls and e-mailing late into the night has become a way of life for Dubose.

It's a far cry from Dubose's past life, where he spent 30 years working for Miami-Dade County agencies before retiring last April. The 53-year-old former president of Metro-Miami Action Plan Trust recently launched a business venture manufacturing and selling a diesel engine exhaust-system component -- dubbed ``the tube.''

But to the co-founder and president of VA Corp. in Miami Lakes, it's called Vibol, which is designed to reduce the stress placed on joints in exhaust systems in buses, trucks and boats.

''When a bus or truck breaks down, you pay the mechanic $18 to $20 an hour. The vehicle is out of service. You're not producing revenue,'' Dubose said, adding that Vibol is guaranteed to last two years, much longer than competing technology.

The gold-colored tube, which is retails for $100 to $175, impressed Florida Detroit Diesel-Allison, a diesel engine and component part manufacturer in Miami.

''The product was a perfect compliment to what we do in everyday business,'' said Sergio Jiminez, president of Florida Detroit Diesel-Allison, now the distributor of Vibol for North, Central and South America. ``They have the right product, we have the right people.''

Vibol, which has been on the market since November, is being used in Miami-Dade and Broward county transit buses, as well as by Alabama-based North American Bus Industries.

Dubose, who has coordinated trade missions to South Africa, was on a personal trip a year ago when a friend insisted that he see an airplane using Vibol. He had already been planning to retire and become a retail developer in Miami.

''I believe in being open to opportunities when they present themselves,'' said the bespectacled, mustachioed man. Dubose partnered with Stevens, a lawyer, to get the manufacturing and distribution rights from Vibol Marketing International South Africa for the device.

Wearing a deep green polo shirt with Vibol embroidered in cream letters, khakis and brown moccasins, Dubose looks every bit like a golf-loving businessman. He is, except that his new workload rarely gives him time for golf.

His days start at 6 a.m. After exercising, he checks his e-mail before going to the office. With a seven-hour time difference between Florida and South Africa, Dubose often continues e-mailing until 1 or 2 a.m. And then there are the business trips to South Africa every two months.

''It's a 24-hour type thing,'' Dubose said. ``There's no such thing as days off.''

With an investment of $100,000 into the company, the Tampa native is gambling with his retirement funds and personal savings.

''You are making tremendous sacrifices,'' he said. ``Business is a risk.''

Gone are the support systems Dubose had when he headed the Metro-Miami Action Plan Trust, constructing affordable housing and directing the creation of the first African-American-owned Denny's restaurant in the Southeast. Now, he has to resort to phone cards to save money on calls to Africa, select brochures and pens with the company logo, and meet with the CPA to discuss the payroll, which includes three employees.

Besides Stevens, there are two other investors, who he declined to name. Additional capital was obtained through banks.

''You are accountable to everyone -- investors, partners, yourself,'' he said.

It's a scary thought.

The father of three faces additional hurdles.

''It's doubly difficult for blacks to get access to capital,'' Dubose said. ``That's no reason to fail -- to use it as a stumbling block. Those are realities.''

And although South Africa has huge potential, Americans tend to overlook the region as it moves from apartheid to capitalism, Dubose said.

''The stereotypical image people have of Africa is of black, people of color,'' he said.

Yet, South Africans view America as a monster of a market.

As a result, they tend to be more cautious. ''You've got to understand you're going into a different culture,'' Dubose said. ``They don't move as fast as we do.''

Dubose and Stevens estimate that Vibol will yield some $45 million in annual sales within three years. Sales now are about 2,000 units a month. The company is outsourcing manufacturing, through Vibol Marketing International in Cape Town.

As plans to build a manufacturing plant in South Africa are underway, Dubose travels around the state making presentations to companies like Disney.

He's confident that the softening economy won't affect sales of the product, which is dependent on public agencies and businesses that use heavy-duty trucks, buses and ships.

And he is finally able to practice what he's been preaching. ''I tell everybody I didn't retire,'' he said. ``I changed careers.''