Had a very informative conversation today with a MOCO engineer....... crank issues began to escalate when the MOCO removed the timken bearing. One problem with the absence of the timken is negative torque applied to the crank when the rear brake is applied and the clutch is not engaged. Many riders take it easy on their equipment and one thing is to brake and when the bike starts to shudder, the clutch is then engaged....this could give the MOCO a way out of warranty issues...
Another issue with the new cranks is that where the crank is internally threaded on the cam side....is this perfectly centered in the end of the crank. Because of the removal of the timken,If the internal threads are not perfectly centered then a vibration is transferred to the left side of the crank, which the timken help to absorb, and increases issues with the compensator.
The Timken bearing is a tough setup and will tolerate off axis rotation (wobble) of the sprocket shaft for an indefinite period. It is very rare to see one of these bearings fail. Having said this, I believe that some of the Engineer’s remarks may have been lost in the translation.
The Timken left main was used with the bolt together crankshaft from 1955 through the last EVO built in 2000. Pulling an early machine down and finding a shifted set of wheels was not at all uncommon. It was also not unheard of to see flywheels shifted to the point where they actually made contact with the oil scraper in the crankcase.
The difference between the early machines and the Twin Cam is that the early BT engines would run indefinitely with a set of shifted flywheels; the Twin Cam will not. The early oil pump setup was unaffected and the cam and pinion gears would run indefinitely before failing. A shifted set of wheels in a Twin Cam will quickly destroy the oil pump and left main roller bearing on 2003 and later machines.
The point is that the Timken left main didn’t prevent flywheel shift in the early machines and it doesn’t make sense that it would in the Twin Cam. Consider that a flywheel shift occurs when either the left or right flywheel continues rotating after the other has slowed or stopped.
I can see how a basis for this argument could be formed. Conceptually the Timken bearing provides greater off axis support of the sprocket shaft which moves off axis when a flywheel shift occurs. Stir in left and right main bearing clearance, crankshaft and crankcase flex, plus 45 years of practical application and there is no useful support for a claim that the Timken left main will prevent a flywheel shift.
JMHO
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Topic: WTF Caused This Failure?!!! (Read 6491 times)