Wastegate Shim Fabrication and Installation

Introduction

Shimming the wastegate involves installing washers or gaskets between the wastegate diaphragm and valve body. This increases the preload on the wastegate spring and raises the boost pressure at which the wastegate opens.

Fabricating Shims

Shims can be fabricated using one of two methods:

1. Trace the shim template onto a piece of sheet metal.
2. Disassemble the wastegate and trace the bottom flange of the diaphragm directly onto a piece of paper to create a template. See the installation procedure below for disassembly instructions.

Shim Installation

Tools

• 6 mm hex key or 6 mm Allen head socket
• 8 mm hex key or 8 mm Allen head socket
• Source of pressurized air (for reassembly verification)

Procedure

1. Remove the wastegate from the car using EXH-03.
2. Remove the three Allen head bolts (6 mm) holding the wastegate diaphragm to the valve body.

Note: Two of the three Allen head bolts also secure the wastegate mounting bracket to the wastegate body. Mark the bracket orientation on the wastegate body before removal.

3. Remove the wastegate valve. The valve has an Allen head insert at its base (8 mm).
4. Separate the wastegate diaphragm from the valve body. Insert two shims between the valve body and the bottom flange of the diaphragm. Insert the Allen head retaining bolts.

Note: If the wastegate was removed while leaving the mounting bracket in the car, install only the retaining bolt that threads into the tack-welded nut on the diaphragm flange at this stage. Before torquing, verify that the remaining two bolt holes in the shims are aligned with the holes in the valve body and diaphragm flange.

5. Torque the diaphragm retaining bolts to 20 Nm (14 ft-lb).
6. Install the wastegate in the car using EXH-03.