WINNER.

John & Horace Dodge died within a year apart. What did the brothers both suffer from which found them dead less than a year apart?

pneumonia , and cirrhosis in jan and dec 1920

John died from the Spanish flu and Hoarce died from phenemonia

Dodge Brothers cars continued to rank second place in American sales in 1920. But that year, tragedy struck as John Dodge was felled by pneumonia in January. His brother Horace then died of cirrhosis in December of the same year (reportedly out of grief at the loss of his brother, with whom he was very close

Wikpedia had what i listed. Whos up?

wtg alk, I found the same causes.

Death and legacy
In January 1920, Dodge and Horace contracted influenza and pneumonia while in New York City. Dodge died on January 14, 1920, aged 55. He was interred in the family mausoleum in Detroit's Woodlawn Cemetery with two Sphinx statues between them. Horace died the following December, and in 1925 their widows sold the Dodge Brothers automobile business to Dillon, Read investment bankers for $146 million.

http://en.wikipedia.org/wiki/Dodge_(car) here is what wikipedia says

I searched John and Horace Dodge came up (John Elgin Dodge in wikpedia). Not sure how to put link on here but under sale to Ford artical is where i came up with my answer.

This is all in fun. My Trivia book stated: Dodge, John & Horace Their first car came off the assembly line in 1914. Both brothers died within less than a year of each other during the influenza epidemic in 1920.
I varified it here before asking it and had same result: http://en.wikipedia.org/wiki/John_Francis_Dodge said In January 1920, Dodge and Horace contracted influenza and pneumonia while in New York City. Dodge died on January 14, 1920, aged 55. He was interred in the family mausoleum in Detroit's Woodlawn Cemetery with two Sphinx statues between them. Horace died the following December, and in 1925 their widows sold the Dodge Brothers automobile business to Dillon, Read investment bankers for $146 million.

alk's answer matched what I had found, so I can only go by what I was looking for.