AW55-50SN Master Rebuild Kit

If your Volvo S60, Saab 9-3, Saturn Vue, Chevy Equinox or Nissan Maxima is slipping on the 2-3 or 3-4 upshift, flaring between gears, or showing dark fluid with friction material in the pan, the AW55-50SN under it has usually worn past the point where a valve body or solenoid repair will save it. This is a complete master rebuild kit for that unit (also sold as the AW55-51SN, AF23 and AF33): a full set of friction plates, steel plates, the pan gasket, valve body separator gaskets, front and side seals and the full O-ring and sealing kit, all in one box so the transaxle comes back together with nothing old in the clutch packs.

What the master rebuild kit does in an AW55-50SN

The AW55-50SN is an Aisin Warner five-speed transaxle that gets its gears by applying several multi-plate clutches and brakes, plus a band, in different combinations, with the valve body and linear solenoids controlling the apply pressure. Every one of those clutch packs wears at roughly the same rate, and the rubber that seals the pistons hardens with heat and age. When one pack burns, the debris travels through the whole unit. A master kit replaces the wear items in every pack and every seal in the case at once, so the rebuilt unit holds pressure evenly and the adaptive shift control has a consistent baseline to learn from.

Symptoms that point to a full rebuild

• Slipping or engine flare on upshifts, worst when the fluid is hot
• Delayed engagement into Drive or Reverse after the car sits
• Burnt-smelling fluid and fine clutch material on the pan magnet
• Harsh, inconsistent shifts that keep coming back after adaptation resets
• Leaks from the axle seals, pan or case that point to tired rubber throughout

How to confirm before you buy

Many AW55 complaints are valve body or solenoid wear, not burnt clutches. Sonnax documents worn bores in this valve body and the linear solenoids that feed line pressure, and those faults cause harsh or soft shifts without any clutch damage. Pull the pan first: clean fluid with no friction debris points toward the valve body, while dark fluid and clutch material means the packs are gone. Our AW55-50SN service guide walks through the checks, and our guide to Aisin slipping under load covers pressure testing to separate a slip from a flare.

Fitment

This kit is cataloged for the AW55-50SN, AW55-51SN, AF23 and AF33 in: 2002-2006 Saturn Vue and Ion, 2002-2006 Opel/Holden Vectra, 2005-2007 Chevrolet Equinox, 2006-2007 Pontiac Torrent, 2007-2008 Suzuki XL7 3.6L, 2004-2007 Saab 9-3, 2002-2007 Saab 9-5, 2001-2007 Volvo C70, S40 and S60, 2000 Volvo S70, 2003-2004 Volvo S80, 2005-2006 Nissan Altima 3.5L, 2004-2006 Nissan Maxima 3.5L and 2004-2007 Nissan Quest. ATRA's Gears magazine notes the GM, Volvo, Saturn, Nissan and Saab versions are not interchangeable as complete units, so compare the gasket and plate counts against the parts you pull. If you are unsure which version you have, send us the year and VIN before ordering. Browse the rest of our Aisin parts in the Aisin transmission collection.

Install notes

• Soak every new friction plate in fresh ATF before stacking, and set each pack clearance with the selective plates rather than trusting stack height.
• Air-check each clutch piston after assembly so you know it seals before the case is closed.
• Inspect the one-way clutch while the unit is apart; a worn one causes a slip or bang that new frictions will not fix. We stock the AW55-50SN sprag clutch if yours is damaged.
• Do not reuse tired linear solenoids in a fresh unit. The AW55-50SN 8-piece solenoid set is the cheapest time to replace them.
• When you refill, the band anchor on the side of the case looks like a fill plug. Loosening it drops the band and leaves you with no 3rd gear.
• Fill with a JWS 3309 type fluid (Volvo, Saab and GM all sell it under their own part numbers), then clear adaptations and drive the car through repeated shifts so the module relearns. See our relearn guide.

The kit covers the soft parts only. Drums, the pump, bushings, the torque converter and the valve body are separate, so plan those based on what you find on the bench.

Does this kit fit both the AW55-50SN and the AW55-51SN?

Yes. It is cataloged for the AW55-50SN, AW55-51SN, AF23 and AF33 family. The versions in different makes are not interchangeable as complete transmissions, so match the plates and gaskets to what comes out of your unit, or send us your year and VIN.

What comes in the box?

Friction plates, steel plates, the pan gasket, valve body gaskets, front and side seals and the O-rings and sealing parts for a full overhaul. Drums, bushings, the pump, solenoids, filter and torque converter are not included.

Will a rebuild fix harsh shifts on my Volvo or Saab?

Only if the clutches are worn. Harsh or erratic shifting with clean fluid is often valve body bore or linear solenoid wear. Check the fluid and pan debris first, and plan on valve body work or new solenoids if you rebuild anyway.

What fluid should I use after the rebuild?

A fluid meeting Aisin Warner JWS 3309. Volvo, Saab and GM each list it under their own part numbers, and several aftermarket fluids carry the approval. Do not use a generic Dexron or Mercon fluid.

Do I need to do a relearn after installing it?

Yes. Clear the adaptive values with a capable scan tool, then drive through repeated light and medium throttle shifts so the module relearns the new clutch fill times. Expect shift quality to settle after the first drives.

• Aisin AW55-50SN Service Guide: Saab, Volvo, Malibu, and Saturn Vue
• Aisin Slipping Under Load: Root Causes and Fixes
• Adaptive Relearn After a Valve Body Swap or Rebuild
• Aisin Overheating: Why It Happens and How to Prevent It