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Crankshaft Group - Crankshaft Measurements

• Crankshaft radial clearances can be checked with the engine in the vehicle.
• In the UK, only Plastigage PL-A is required. This is a plastic thread of high precision thickness.
• A short length of Plastigage is laid on a thoroughly cleaned bearing journal. The cap is replaced and tightened to 59Nm. Note that 13-21 states the nominal torque.
• The bearing must NOT be rotated.
• The Plastigage thread has a known and carefully controlled thickness. When the bearing cap is tightened down, it is squashed into the available space.
• When the bearing cap is removed, the width of the Plastigage thread reveals the tolerance of the bearing. If it is tight, the Plastigage will have been spread quite wide. If it is slack, the Plastigage may hardly have spread at all.

• The Plastigage packaging carries a crude, useful and surprisingly accurate visual appraisal tool.
• There are both both radial and axial tolerances.

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