The Becker's Email
Start w/ census records for your grandfather Sam and work back in time. That is, find him on the 1940 census and then the 1930 census. Read the info in all the columns. Look for an obituary to see if it mentions any surviving siblings. Similarly, if you know where his brother Max lived, do the same for Max. (You should be able to go back to the 1920 census at least. for Max. Use familysearch.org as it is free and/or Ancestry.com which requires a subscription but is available free at many public libraries. Preferably, don't just rely on one genealogy website as they often use different transcribers and have different search engines. While there is overlap in databases, some are different.
You say Sam arrived the US through Providence around 1924. A Srul Weinstein b.c. 1908 arrived Providence on the ship Sinaia out of Constanta,Romania on 1 Oct. 1925. He was born in Jashcov. The jewishgen townfinder search yields one possiblity: Zhaskov, Kiev district, Ukraine province, Sov. Union between the wars, c. 1930. Today it is Zhaskiv, Ukraine. He was going to his brother Mendel Weinstein at 1327 N. 17th St., Philadelphia. Could this be your grandfather? source: Ancestry for the manifest
As Havey Kaplan suggested, you can also look for naturalization records, marriage/death records and other records such as WWII draft registration for Sam and WWI and possibly WWII draft registrations for Max. There are lots of databases to check, but start with the basic ones like census records first.