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Home >> Audi >> 2010 >> S4 Standard >> Repair and Diagnosis >> Drivelines & Axles >> Driveshaft & Universal Joints >> Final Drive & Differential - Rear Final Drive - Sport Differential (Sedan) >> 39 Final Drive, Differential >> Rear Final Drive, Disassembling And Assembling >> Hydraulic Control Unit, Disassembling And Assembling

Hydraulic Control Unit, Disassembling And Assembling

Fig 1: Exploded View Of Hydraulic Control Unit
GWWA39-10370Courtesy of AUDI OF AMERICA, LLC
  1. Bolt
    • 5 Nm
  2. All Wheel Drive Pump -V415-
  3. O-Ring
    • Always replace.
  4. Adapter
    NOTE:

    The adapter could fall out when removing the All Wheel Drive Pump -V415-.

    Insert the adapter into the recesses in the hydraulic pump before installing the All Wheel Drive Pump -V415-.

  5. Hydraulic Pump
    • Consists of a guide ring, the housing and six pistons
    • Assembling. Refer to Fig 2
  6. Ball Bearing
    • Can be installed and removed by hand
  7. Left Line
    • Tighten the nuts to 30 Nm.
    • Is installed between the hydraulic control unit and the left chamber
    • Tighten both nuts hand-tight when installing
  8. O-Ring
    • Always replace.
  9. Oil Pressure/Temperature Sensor -G437-
  10. Oil Pressure/Temperature Sensor 2 -G640-
  11. All Wheel Drive Clutch Valve 2 -N446-
  12. All Wheel Drive Clutch Valve -N445-
  13. Bolt
    • 2.5 Nm
  14. O-Ring
    • Always replace.
    • Mount onto the Clutch Valve --
  15. Pressure Spring
    • Insert into the guide. Refer to -item 16- below (See Fig 1).
  16. Guide
    • Installation position, large diameter faced the ball. Refer to -item 17- below.
  17. Ball
    • Insert into the guide before installing. Refer to -item 16- above.
  18. Hydraulic Control Unit Housing
    • With centering pins -arrows-
    • The centering pins lock the hydraulic control unit and seal to the final drive housing.
  19. Ball
    • Install in the hole in the shuttle valve before installing, Refer to -item 21- below.
  20. O-Ring
    • Always replace.
  21. Shuttle Valve
    • 8 Nm
    • Removing and installing. Refer to Fig 4.
  22. Gasket
    • With strainer
    • Install on the centering pins in the hydraulic control unit housing
  23. Right Line
    • Tighten the nuts to 30 Nm.
    • Is installed between the hydraulic control unit and the right chamber
    • Tighten both nuts hand-tight when installing
Fig 2: Assembling Hydraulic Pump
GWWA39-10404Courtesy of AUDI OF AMERICA, LLC

-- Install the six pistons -A- in the housing -B-.

-- Install the guiding ring -C- so that the piston touches the collar -arrow-.

-- Insert the hydraulic pump -1- with the guide ring -2- in the in the hydraulic control unit housing.

Fig 3: Hydraulic Control Unit Housing
GWWA39-10447Courtesy of AUDI OF AMERICA, LLC

Function Test 

-- Turn the hydraulic pump -1- several times. While doing so pay attention to the following:

Fig 4: Removing/Installing Shuttle Valves
GWWA39-10403Courtesy of AUDI OF AMERICA, LLC
NOTE:

Remove the All Wheel Drive Pump -V415-, hydraulic pump and ball bearing beforehand. Refer to -item  6- Ball Bearing (See Fig 1).

-- Remove the shuttle valves -A-. Always remove the ball -C- as well.

-- Insert the ball into the hole in the shuttle valve when installing.

-- Install the shuttle valve all the way with a new O-ring -B-.

-- Tighten the shuttle valve to the tightening specification. Refer to -item  21- Shuttle Valve (See Fig 1).