Power Steering Rack Rebuild (Reseal)

Introduction

Procedure contributed by Karl "Doc" Wilen.

This procedure covers the complete disassembly and reseal of the Porsche 944 / 944S power steering rack. A leaking rack does not always require replacement — if the rack body and steering gear are in good condition, installing a seal kit can restore proper function at considerably lower cost and effort than full replacement.

Before beginning this procedure, the rack must be removed from the vehicle. Refer to STEER-01 for the rack removal procedure.

Seal kits for this procedure are available from Porsche-specialty parts suppliers. A rebuilt rack with core exchange is also an option if the rebuild is not feasible.

Note: This is a detailed, time-consuming procedure. Set aside adequate bench time and work in a clean environment to avoid contaminating the seals.

Tools

• Metric socket set
• Long socket extensions
• Small pick (a dental pick is ideal)
• Hammer
• Punch
• Needle nose pliers
• 6mm Allen key
• Reseal kit specific to the 944 rack

Procedure

Rack Disassembly

1. With the rack secured on the bench, locate the locking collar on the bronze steering sleeve. Using the punch and hammer, carefully drive out the roll pin or locking pin that retains the locking collar. Slide the locking collar back along the bronze steering sleeve to expose the control tower.

2. Remove the top cap from the control tower. The cap is typically retained by a circlip or threaded collar — use the appropriate tool for the style on your rack. With the cap removed, the wiper seal and o-ring at the top of the tower are accessible.

3. Carefully disassemble the rack internals. The major components are:

   • Shuttle — the sliding hydraulic piston
   • Steering rod — connects shuttle to the rack output
   • Steering gear — the pinion and associated valve body
   • Control tower — the central hydraulic control housing
   • Steering sleeve (bronze) — the outer sleeve around the steering shaft

   Lay each component out in order as it is removed.

Steering Gear Seal Replacement

4. Inspect the steering gear o-rings. On original racks, these are typically white hard plastic rings. The reseal kit provides blue plastic rings over rubber o-rings as the replacement. Remove all old rings and o-rings from the grooves on the steering gear using the small pick. Take care not to scratch the sealing surfaces.

5. Install the new rubber o-rings in each groove, then seat the new blue plastic rings over the top of the o-rings. Ensure the plastic rings are fully seated without gaps.

Control Tower Seal Replacement

6. The control tower contains wiper seals on both the driver's side and passenger's side. Begin with the bottom wiper seal on the driver's side — this is one of the most critical seals in the rack.

   Using the small pick, carefully remove the old wiper seal from the driver's-side bore of the control tower bottom. Note the orientation of the seal lip before removal.

7. Move to the passenger side of the control tower. Here you will find a large o-ring seated in an external groove, and a separate shuttle o-ring. Remove both old o-rings using the pick and replace with the new o-rings from the kit.

Steering Shaft and Shuttle Seal Replacement

8. Inspect the steering shaft and shuttle assembly. There are two o-rings located underneath the shuttle seal mechanism. Remove and replace these o-rings.

9. The shuttle interior contains a wiper seal and a hard plastic spacer. Remove the old wiper seal using the pick. The plastic spacer may be reusable if undamaged — inspect it carefully.

10. On the outside of the shuttle, locate the hard plastic ring. The replacement o-ring from the kit installs on the outer side of this ring, not between the ring and the shuttle body.

Bronze Steering Sleeve Seal Replacement

11. The bronze steering sleeve contains a wiper seal, a plastic spacer, and a plastic guide ring. These are accessible after the sleeve is removed from the rack body. Extract the old wiper seal and inspect the spacer and guide ring.

12. Work the old wiper seal and spacer out of the bronze sleeve. Use the pick carefully to avoid scratching the bore.

13. When installing the new wiper seal into the bronze sleeve, pay close attention to orientation. The groove side of the seal faces a specific direction.

    Caution: The orientation shown in the photo below is the opposite of the correct installation direction. Use the photo as a reference for identifying the groove, but install the seal with the groove facing the correct direction for your application. Verify against the reseal kit instructions before pressing the seal home.

Rack Reassembly

14. Reassemble all components in reverse order of disassembly. Work cleanly — lubricate new seals and o-rings lightly with clean ATF before installation. Do not use petroleum-based grease on rubber seals.

15. When reinstalling the locking collar on the bronze steering sleeve, ensure the roll pin or locking pin is fully seated and the collar is positioned correctly before driving the pin home.

16. Reinstall the control tower top cap and torque to the appropriate specification per the reseal kit instructions.

17. Once fully reassembled, reinstall the rack in the vehicle per STEER-01. Bleed the power steering system fully and check for leaks.

Note: A successfully resealed rack should have no external leaking at the sleeve or control tower. If leaks persist after the reseal, inspect the rack body itself for cracks or porosity.