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motor bearing problem

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I bought my ADC shunt motor used on ebay. I put the car together and got it running. The motor made a sound like a loud wheel bearing which, since I'm not that familiar with large electric motors, I didn't know if it was normal or not.

I had the bearing replaced and it sounded much better, much quieter.

Now, about 3 months later, the motor is making the same loud bearing noise that it did before.

My questions are:

Could I have received a bad bearing?

Could the shaft be bent and put undue stress on the bearing causing it to be louder?

Could the bearing be improperly seated in the front motor mounting plate?

Could the motor and trans be out of alignment to such an extent that the bearing is overstressed?

Could there be some other reason or cause for this bad bearing noise?

I am using a Lovejoy spider coupling with a plastic insert that should compensate for a small misalignment.

To fix the problem, I've got to take most of the system apart. I would like to replace the bearing but I'm afraid that the new bearing will also fail.

Thanks for your ideas.

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· Registered
780 Posts
Hi. With a plastic insert in the lovejoy joint, misalignment should be less of a problem. I would expect that insert to disintegrate before the bearing goes out. Which of the two bearings is making the noise?

For what is worth, I bought a brand new motor off eBay that came factory boxed. Upon starting it, I noticed the bearings were busted. My guess - and by seeing one of the fan fins slightly bent - is that someone dropped it while being manufactured and damaged the bearings. I replaced the bearings myself with new, high quality ones. Are you sure they gave you a new set of bearings and not just repacked the old ones?

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