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Home >> Fiat >> 1978 >> 128 Base, 2D Sedan >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Mechanical >> 128 & X1/9 4 Cylinder >> Pistons, Pins & Rings >> Piston Pin Replacement

Piston Pin Replacement

  1. Remove piston and rod assembly as previously outlined. Remove circlips and drive out piston pin using a suitable driver (A.60251).
  2. Check fit of pin in piston. Pin should be push fit in piston and should not fall through under its own weight. There are two classes of piston pin and piston bore sizes. If piston pin is replaced it must be replaced with a pin of the same class. Class of piston is stamped on bottom and class of pin is stamped on face of pin.
    PISTON PIN & BORE CLASS SPECIFICATIONS

    Application Size
    Piston Pin
      Class 1 .8658-.8659" (21.991-21.994mm)
      Class 2 .8659-.8660" (21.994-21.996mm)
    Piston Pin Bore
      Class 1 .8660-.8661" (21.996-21.999mm)
      Class 2 .8661-.8662" (21.999-22.002mm)
  3. Check piston pin clearance in connecting rod. If clearance is more than specified, drive bushing from connecting rod using a suitable driver (A.60054). Install a new bushing with same driver and ream to size with a new piston pin.
  4. Piston pin bore in piston is offset 0.08". Install connecting rod with numbered side on same side as offset. Lubricate piston pin and secure connecting rod big end in a vise. Place piston in proper position with connecting rod and push in piston pin using a suitable driver (A.60251). Install circlips.
  5. Install piston and connecting rod assembly as previously outlined.
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