SEGMENT GP-SPROCKET 1880908 - Caterpillar

3408B Engines In All ApplicationsFor sometime, new crankshafts with thicker cheeks have been used in 3408B Engines in all applications to give longer crankshaft life. A new flywheel housing with a cast-in pocket is used on these engines because of the thicker end cheek on the new crankshaft. Although the former crankshaft and housing are both serviced, there are situations where it is desirable to reuse the former housing with the later crankshaft, such as on a replacement engine or short block.
A relief can be machined in the former flywheel housing so the later crankshaft with the thicker end cheek can be used with this housing. This provides clearance for the end cheek. See illustration.
Machining of the former flywheel housing is indicated by the shaded area.