From Wikipedia:
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Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet (PM) machine. It is also known as detent or 'no-current' torque. Cogging torque is an undesirable component for the operation of such a motor. It is especially prominent at lower speeds, with the symptom of jerkiness.
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Normally cogging is uniform in intensity but the cogging from the Prius transaxle was variable. It was very stiff then looser, then loose then stiff in a sort of random way. I would think this points to shorted coils interacting with the magnets. Why it would be "random" like that is confusing because presumably the magnets are uniform and would interact with the coils similarly. On second thought, if the number of coils vs magnets is different then a pattern might emerge where sometimes multiple shorted coils are interacting and sometimes just one. Make sense?
I'm not sure I'm up for a rebuild. Perhaps once I get a good replacement in there I could try it on the existing one.
I read on another forum of someone getting a tranny replaced for free by a dealer at 110K miles. I should give this a shot. It cant hurt.
I like the idea of a tranny block heater. I use one in my Previa engine year round and have been thinking of installing one in my tranny and diff. Good to know those pad heaters are unreliable. I won't get one of those. I know that you can get bolt on ones but have not looked into it. I think MetroMPG tested one of those here. Do you know of bolt
through designs that would stand up to oil?
What is the simplest way to get a oil sample?
Darn TIS won't take canadian credit cards
so I'm SOL for now on the shop manuals.