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IH: Engine Mechanicals

Roller Bearing Inspection (1957-1976)

In a letter dated May 9, 1977, an HD interoffice memo was sent regarding an inspection of parts stock roller bearings. Some roller bearing part numbers were found to have incorrect diameters. A new micrometer was purchased to remedy this problem.
Two of those part numbers are gear shaft (9421) and crank pin front rollers (9150A) for 1957-1976 Sportsters.
In light of this oversight, a listing of part numbers with their correct dims and tolerances was issued as in below:

Used for 57-76 Sportster gear shaft roller bearings	Diameter	Size	Length
9421	.1876“ - 1974”	Standard	.800“ - .796”
9422	.1878“ - 1876”	+ .0002“	.800” - .796“
9423	.1880” - .1878“	+ .0004”	.800“ - .796
9424	.1882” - .1880“	+ .0006”	.800“ - .796”
9425	.1884“ - .1882”	+ .0008“	.800” - .796“
9426	.1886” - .1884“	+ .0010”	.800“ - .796”
Used for 54-85 Sportster and K Model front crankpin roller bearings	Diameter	Size
9150A	.1875“ - .1874”	Standard	.480“
9152A	.1877” - .1976“	+ .0002”	.480“
9154A	.1879” - .1878“	+ .0004”	.480“
9156A	.1881” - .1880“	+ .0006”	.480“
9158A	.1883” - .1882“	+ .0008”	.480“
9160A	.1885” - .1884“	+ .0010”	.480“
9161	.1873” - .1872“	- .0002”	.480“