Aisin AW55-50SN Pump Assembly 12 Spring 0.420 Gears Volvo Saab Nissan Used

Aisin AW55-50SN Pump Assembly 12 Spring 0.420 Gears Volvo Saab Nissan Used

Used OEM unit pulled from an inspected donor transmission, cleaned and visually inspected before listing. Photos show a representative unit of this exact part and variant — see the fitment and casting notes below to confirm your match.

• SKU: AW-AW55-PM-U-01
• Includes: One good used complete AW55-50SN / AW55-51SN oil pump assembly as pulled: pump body with the drive and driven pump gears installed (0.420in / 10.7mm thick gear set), plus the pump cover / stator support carrying the 12-spring-guide B1 coast-brake piston arrangement, in the 3-clutch-inner / 3-clutch-outer B1 configuration. NOT included and NOT implied: torque converter, input shaft, valve body, filter, front pump seal, pump-to-case O-ring or gasket, sealing rings, and no new bushings - the stator support bushing is a wear item on this unit (it is a known failure point, the sleeve can gall against the converter neck) and should be inspected and replaced as a matter of course.
• Warranty: 30-day return-or-replace after delivery
• Shipping: UPS Ground from our Tennessee warehouse, 2 business day handling

OEM / interchange references (verify against your casting/tag):

• 21500AA

Fits (engine/year matters — read carefully): This is the Aisin Warner AW55-50SN / AW55-51SN 5-speed front-wheel-drive automatic pump assembly, the same unit GM/Opel badge AF23-5 and AF33-5, in the 12-spring-guide configuration used on the GM, Saab, Opel and Volvo side of the family (2001-up production).

Important: Three things decide whether this pump bolts up, and none of them are printed on the outside of the case. FIRST, COUNT THE SPRING GUIDES. Pull your pump and look at the back face of the pump cover (stator support side), at the B1 coast-brake piston return-spring assembly. Count the little cylindrical spring seats/guides around it. This pump is the 12-GUIDE version. There is an 8-guide version that looks nearly identical and is the one normally found in Nissan RE5F22A units - it is a different part number (Transtar 89500BA vs 89500B/BB) and will not give you the right B1 apply. If you count 8, this is the wrong pump. SECOND, MEASURE THE STATOR BUSHING BORE. The 12-guide pump was built in two bores: about 0.840in and about 0.870in ID, matching the two input-shaft diameters used in this family (.843in small shaft vs .873in large shaft).

Before you order: confirm your transmission code and casting/part numbers. Not sure? Message us through eBay with your VIN or transmission tag and we will confirm fitment the same business day. Rebuilder shops — ask about volume pricing. We stock transmission hard parts by family and can hold inventory for scheduled builds.