Tech article TA0023: TA0023

Bulletin number

1HDM5V2A05

Component

Power train

Summary

TECH ARTICLE TA0023: TA0023: Crankshaft Rod Bearing. Purpose: Technicians have been falsely identifying connecting rod bearings as failed due to a perception of resistance as the rods are rotated. The clearance of the Twin Cam and Milwaukee-Eight® crank pin bearings are maintained to a very tight range. This optimizes performance and maintains low mechanical noise in operation. The connecting rod bore can also distort slightly in operation due to stress relaxation. As a result, bearing clearance decreases due to the contact zone broadening and the load being distributed over more rollers. The combination of a bore being slightly out of round and reduced bearing clearance can result in varying degrees of resistance through the range of motion. Axial clearance is also tightly controlled for proper alignment. For these reasons, zones of resistance can be found when the connecting rods are rotated by hand through their range of motion. Resistance during rod motion, by itself, is not an indication of a performance or durability concern.

Owners of these vehicles have filed 205 complaints in the transmission category.