1981/03/06 Caterpillar

Modification Of Flywheel Prevents Loose Clutch Pilot Bearing


3406, 3408 Truck Engines Equipped With Brake Savers

There have been reports of loose clutch pilot bearings in the flywheels on some 3406 and 3408 Truck Engines equipped with BrakeSavers.

The clutch pilot bearing is pressed into the flywheel before the flywheel is installed in the BrakeSaver. It is possible for the small, raised area on the BrakeSaver rotor assembly to cause distortion of the flywheel when the bolts are tightened to the correct torque. This distortion loosens the clutch pilot bearing.

A modification can be made to the 9N2644 and 9N2645 Flywheels, which are used with the BrakeSavers, if the clutch pilot bearing is loose.

A counterbore 101.6 mm (4") in diameter and 0.635 mm (.025 ") deep can be added to the flywheel. It is on the side of the flywheel nearest the engine and has the same center line as the flywheel bore.

The counterbore will prevent the distortion and a loose clutch pilot bearing.

The Illustration gives the dimensions for the counterbore.

Dimensions for counterbore to be machined into 9N2644 and 9N2645 Flywheels.

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