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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This is one of our tests to qualify an IMS for our upgrade procedure. If the shaft has more than .005" of runout on the main sprocket, we fail it. Most shafts however don't have any. Only when the shaft has been subjected to an IMS failure or some other kind of trauma (broken chain), is it that we see runouts starting at .015" and only getting worse from there.
The other issue we check for is concentricity of the bearing housing bore as well as runout and taper. Most usually have a few tenths, but we've seen some that have several thousands when the sprocket has zero runout and in those cases, we will junk those shafts too. Unfortunately, this is all stuff you can't easily check for when the intermediate shaft is still in the car and specifically why carrying out a retrofit procedure on a bearing that has failed or is close to failure is not advised (excluding the foreign object debris that has already compromised the engine and will compromise the replacement bearing).
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