A fluid accumulator assembly used with 2002 to 2005 model years of ZF Getriebe's GmbH ZF-6HP19, ZF-6HP26, ZF-6HP32 automatic transmissions, and model years up to 2011 of Ford's 6R60 automatic transmissions. The fluid accumulator assembly includes a piston that can be received into a bore that is in fluid communication with a solenoid-controlled fluid circuit of the transmission. The fluid accumulator assembly also includes a compression spring sized and configured to fit within the piston, and used to provide an urging force to the piston.