Quote:
Originally Posted by Jamesp
Jake,
Any idea of the typical run out on the IMS driven gear? I had the failed IMS from my engine measured at 0.015. Quite a bit for a gear, but as it is a chain drive if may be ok. In any event that was a major driver in replacing the damaged shaft with an undamaged one. My thought at the time was if the IMS gear run out was poorly controlled in the design, additional side loads could shorten bearing life in high run out cases even with a deep groove ball bearing.
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Good thought that few consider. The acceptable runout is less than 1 thou. for my engines.
Too much runout, and the associated timing chains see accelerated wear as well as the replacement bearing. This is one reason why we highly discourage cutting the race of a failed bearing out of a shaft and resurrecting it, because the heat and trauma associated with bearing failure often creates runout that can lead to shaft separation or future bearing failure.
One supplier of "rebuilt shafts" is selling shafts with another bearing design that have previously failed and have been "repaired". We'll see how that works out for them and the buyers.
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