Zero motor 75-7 markings, red sticker, DANGER?

[dozentrio]

I bought a zero 75-7 motor and noticed some additional details on the housing. A red sticker, some permanent marker numbering and also, the "zero" part where it says "zero motorcycles" has been ground down.

Does anyone have any insight into what these things mean? Was this motor used in some high stress testing? Was it modified? Red stickers aren't usually a good thing. Or maybe it means it's particularly fast

What about the serial number? Do we know how to decode that?

 

[liveforphysics]

I don't know anything about the history of your motor, but that's not a bad sticker. It's also nice someone wrote the Sine-Cosine encoder offset on there for you.

If the shaft spins without making bad noises, and it doesn't stink like cooked windings, it's probably a great motor. It's been a decade now, and that's still the best high performance LEV motor I've encountered.

 

[Jrbe]

I bought a zero 75-7 motor
...snip...
the "zero" part where it says "zero motorcycles" has been ground down.
Does anyone have any insight into what these things mean?

Companies that sell parts to oem's will mill off the brand name / logo when they start selling them. For example, buy a water pump for a vw from hepu or graf and you will see they mill off the brand logo(s) that they sell to as the original supplier.
Might be the same for this.

 

[bastens_com]

I have used Zero 75-7R motor that I have used in two of my builds. I was wondering what RPM range you are running. I found an old spec from Zero that says they can run 7500 but I have limited mine to 6000RPM. I would like to run higher RPMs in my side-by-side build but I don't want to kill the motor. What have you found to be a safe RPM range with your motor?

https://www.facebook.com/patrick.basten/posts/10159144792379726

 

[liveforphysics]

Complicated question, I don't have an answer. I run 7300rpm, but I have no idea if it's safe or stable for your application. I think ~6500rpm is an OEM peak RPM, but I think controller commutation frequency current control loop stability is perhaps more of a factor in the 6500rpm limit than mechanical stability of the rotor.

Everything we hotrod things, we are rolling the dice with potential failures induced by increased stresses.

 

[zombiess]

I thought someone had posted on here about these motors failing around 10k RPM. Maybe it was Methods?

This thread has some info
https://endless-sphere.com/forums/viewtopic.php?f=30&t=81009

 

[liveforphysics]

Methods work in that thread was unfortunately all with the SPM rotor (surface permanent magnet).

The IPM rotor motors I've seen be spun up to over 16,000rpm and they mechanically take it, however the amount of eddy heating and core heating is so extreme you only have a handful of seconds at that RPM before overheat.