1997 & Later RE units
Many Chrysler A727, 42-46-47RH/RE, 48RE and A904 transmissions experience rear servo piston sticking/breakage, pin bore wear and reverse band slippage. The servo piston has a tendency to get cocked in the bore, inhibiting band apply. The high reverse line pressure continues to apply against a cocked piston, causing piston breakage. The bore of the piston also wears from side loading, resulting in insufficient band apply pressure. Sonnax has developed billet aluminum pistons 22912, 22912A, 22912B and 22912C to address these problems.