Rap band were in the studio in Autumn.
Band member Mike D said they had been in the studio last autumn laying down tracks despite the musician's illness.
However he insisted that began working together on the fresh songs because Adam expressed his wish to.
He said: ''Adam instigated it. It could only come from him, in terms of where he was at with his cancer treatment.''
Apparently the sick star - who passed away earlier this month wasn't confident in his performance but pulled through eventually.
He added: ''He wasn't sure he was able to do vocals but after a bit we ended up doing them.
''It was a way for him to say, 'Yeah, I'm doing it'.''
New York State Senate recently passed a resolution honouring the late star's achievements.
The J4637 resolution was written by Daniel Squadron - who represents the district of Brooklyn Heights, where Yauch was born - and celebrates his many accomplishments and contributions.
Daniel vowed to hold a vigil in memory of the 47-year-old who succumbed to lymph cancer.
The lifelong fan of the band hailed them for having ''helped redefine and rejuvenate a city on the ropes''.
The senator said: ''Growing up in New York, listening to the Beastie Boys was as basic as carrying an extra subway token in case of emergency.''