Novak 5mm Replacement rotor
 

I think I have another issue with one of my 4.5's. Last fall I bent the rotor on my HV-4.5 in my Maxx. So a couple weeks ago I ordered a replacement 5mm rotor for it. When I installed it, I had a heck of a time getting the end of it to go into the bushing at the back of the motor (it actually hit the circuit board fairly hard a couple times). I thought this was a little odd at the time - seemed way too sloppy to me (I thought the fit would have been tighter through the windings). Over the last couple weeks, I transferred everything over to my G-Maxx chassis, and made complete mess out of the garage. SO last night while I was cleaning things up, I tried to put the old rotor into the sleeve the new one came in, and it wouldn't fit. I think they sent me a mislabeled rotor. I dont think this is that bad in itself, but now I'm a little concerned about what kind of damage I may have done to the sensor board in the motor when I was installing it.
Has anyone replaced their rotors? If so, do you still have the old one(s) and can measure the dia of them? Is the 6.5 a smaller diameter?

You did used the plastic sleeve to guide the rotor in place? the 6.5 and 4.5 rotor are the same. the only difference in diameter are the sintered and the older rotors. The sintered rotors are smaller in diameter than the old ones.

Maybe the the 5mm shafted rotor is smaller in diameter than the orginal 1/8" shafted sintered rotor. Novak said something about a smaller airgap causing the rotor to oversaturate the stator and create heat, which could be why they went with an even smaller rotor. The kv of the 4.5 went from 4800 to 5000 and the kv of the 6.5 went from 3100 to 3400 after the 5mm change which hints a smaller rotor.

The 5mm upgrade rotor requires a new endbell also.

HV Brushless Motor 5mm Upgrade Kit

So, Novak Two, did you just confirm that the rotor I just installed SHOULD have been smaller in diameter than the one I pulled out (assuming that my 4.5 is in fact an older non-sintered rotor)?

Yes, I did. But once the larger portion of the shaft left the sleeve, it became very difficult to control - you know, magnetics and all........

Thanks for the replies.

The 4.5 and 6.5 HV motors always had sintered magnet rotors, with the original shafts. Apparently, we have never listed the rotor dimensions for the HV rotors as we have for the Vel/SS Pro motors, where rotor dimensions are a point of serious interest.

Good catch. I'll check and get back to you. It's definitely something we need to add to the descriptions, now that we have the new 5mm shaft rotor.

I'm fairly certain the motor on this one is one of the originals. I purchased it used from someone on this forum about 2 years ago.
I just ran it up and down the street a couple times, seems to run ok. Its not flipping on its lid like my Revo does, but that may be due to the G-Maxx chassis. I have more tuning to do on the chassis than I do with the motor right now.

Maybe it's one of the original 4400 HV motors sold with the bonded rotor--the orig owner may have upgraded to sintered?

I just checked - yes it is a 4400 HV motor. I have no idea if it was upgraded. I guess it doesn't really matter what the old rotor is/was - I just need to know if this new rotor is going to work. I'll leave it sitting until I know for certain.

You cannot simply install a new 5mm shaft HV rotor into the motors without also upgrading the bearing/endbell assembly linked above.

I know, the new rotor came with the new endbell/bearing.

the 5mm upgrade should fit the 4400 if the endbell and bearing is used?

Thanks novaktwo.

I forwarded this question to Charlie

He asked that you e-mail him directly for assistance. He did comment that installing the rotor can be tricky, but he can probably give you some tips

I was also told that the only significant difference between this 5mm shaft rotor and the original, sintered one is the shaft diameter.

Thanks, I sent him a note!

He confirmed that the old rotor was significantly larger (@1.7mm). Thanks for the support.