LMFAO's Sky Blu Says Redfoo Screwed Him On Royalties

One half of LMFAO is sounding off at the other claiming despite family ties he's been left in the dust.

Sky Blu posted a scathing letter on Facebook about Redfoo, who's also his uncle, calling him out for ditching him after he suffered a debilitating back injury.

Sky, who now goes by 8ky, is trying to drop his new solo LP but says Redfoo's lawyers fired off a letter saying he gets zero LMFAO royalties ... money he needs to underwrite his album. He says he's also been unsuccessful getting his share of money held up by Rick Ross' lawsuit against the group.

8ky claims Redfoo pushed him out of LMFAO and "just kept shuffling everyday without me," going as far as using their trademark party rock theme on his own solo LP.

8ky also sounded off on their label, Interscope, saying it needs to "stop treating artist like cows and chickens and using them for all they can produce and then just discard them without a care."

It's kinda history repeating itself. They're both blood related to Berry Gordy, founder of Motown ... a label that had its fair share of royalty fights.