1HDM5V2A05

Tech Article
TA0023: Crankshaft Rod Bearing
Reference
Last Modified
Models
Category
Markets
TA0023
2018-04-27
Affected Parts
Flywheel assembly
Engine
All markets are affected.
Reason for Revision
Refer to Table 1.
Table 1. Document History
Date
2017-12-06
2017-12-14
2018-04-27
Revision Description
Initial release
Updated Purpose for Tech Article, Action
Updated Complete Tech Article
Purpose for Tech Article
Technicians have been falsely identifying connecting rod bearings as failed due to a perception
of resistance as the rods are rotated. They report rods standing up and not falling under their
own weight.
Cause
®
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.
TA0023 1 / 2
Motorcycles Affected
Refer to Table 2.
Table 2. Motorcycles Affected
Years
1999 - Present
2000 - 2017
2000 - Present
2004 - Present
2009 - Present
Platform
Touring, Touring CVO, Touring Police
Dyna, Dyna CVO
Softail, Softail CVO
Sportster
Trike
Action
Resistance during rod motion, by itself, is not an indication of a performance or durability concern.
Connecting rod bearing failures generally exhibit noise, visible clearance indications, piston to
valve contact, and/or secondary damage in the form of a high levels of steel debris circulating
through the engine. Verify that one or more of these symptoms is present and quantified prior to
attempting to qualify the rod bearing condition.
NOTE
• Connecting rods when placed in limit conditions, defined as positions outside the normal rod
operating position (pinched together or spread to the extent of separation), may exhibit areas
of resistance.
• The induction heat treat operation on Twin Cam and Milwaukee-Eight connecting rods will
"blue" the lower end of the rod and is considered a normal condition. Sportster connecting rods
are not induction heat treated and will be uniform in color.
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