Billet aluminum direct clutch piston for 47RH, 47RE and 48RE transmissions behind the 1994-2007 Dodge 5.9L Cummins, replacing the cast piston that cracks under boost.
SunCoast Diesel part 618-DBP, a CNC-machined billet aluminum direct clutch piston for the Chrysler 618 family: 47RH, 47RE and 48RE, as fitted behind the 5.9L Cummins in 1994-2007 Dodge Ram 2500 and 3500 trucks. It drops into the direct drum in place of the factory piston.
The stock direct piston is cast, and it is one of the first things to let go on a tuned Cummins. Line pressure that has been raised with a valve body kit or a pressure transducer, plus the torque a fueled 5.9 puts through third gear, works the piston until it cracks around the apply face or the sealing ring lands. The symptom is a soft or slipping 3rd, then a burnt direct pack, and it usually comes back again a few thousand miles after a rebuild if the cast piston goes back in. The billet piece has more material behind the apply face and does not flex, so pack clearance stays where you set it.
On the bench it installs like the original. Strip the direct drum, replace the piston lip seals, set the piston in squarely, then reassemble and check clearance with a dial indicator before the drum goes back in the case. Because the billet piston is dimensionally different from cast in apply area, verify your clutch pack clearance and adjust the pressure plate or steels to spec rather than assuming the old stack still measures right. Standard practice on a performance 47RE or 48RE build is to do this piston at the same time as the billet band, strut and anchor.
Fits 47RH, 47RE and 48RE (A518/A618 family) transmissions, 1994-2007 Dodge Ram 2500 and 3500 with the 5.9L Cummins.
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