roller crankshaft thrust washer failure

[englertracing]

4 stroke.
was not ran out of oil.
oil is fed through the end of the crankshaft.

rod.jpg

rod thrust washer.jpg

any ideas?

[hoodeng]

What does the thrust face of the rod and wheel look like on the side of the failure and off side? is the i/d large enough for it to float out of the groove?

Cheers.

[naukkis79]

Either bend rod or crank.

[Kevin Johnson]

The patina from oil exposure is different on the rod beam versus the crankshaft counterweights as well as the case halves. How many times has it been rebuilt and was this an original bearing?

[englertracing]

Kevin its been apart once to fix an issue with the transmission. I replaced only transmission components and the piston and piston pin.
Honda m/c cranks always have a weird copper color on the throws, I suspect that they are cast steel and that they are carburized. It actually looks just the way it did 5 years and about 200 hours ago, at which time it probably had 100 hours. General consensus on the internet is that the crankshaft should be replaced or rebuilt at 250 hours. Would have been a fantastic time to replace mine....


I looked at it a little bit more.
I checked what the side clearance would be with the washer in place, around 0.020"
then I noticed it.

broken shit.jpg

The bearing cage slid over, If you look closely, the cage is in multiple pieces.
I believe the cage broke and abraded the washer.
Interestingly there is no detectable radial play, and it still feels extremely smooth.

[Kevin Johnson]

That is impressive and valuable feedback from other owners. The only comparable thing that pops into my head is when I owned a Mercedes diesel and people warned about the bearings in the vacuum pump typically failing at a known mileage range.