Well that's kinda strange. I just installed the sintered rotor/5mm shaft into my HV4400 and it fits just fine. I used the upgraded endbell and shimmed accordingly.

I've been driving it around the yard and it works great.

The only difference between the sintered and the tuning rotor is diameter, right?

When installing the sintered rotor, I cut off the hollow packaging tube it came in.

I then stuck the hollow packaging tube down into the throat of the motor to help center the rotor while I installed it. It helped.

Anyways, the tube is 14mm in diameter.

I just checked and the 1/8" rotor that I removed, and it is 14mm in diameter.

Is there something here I'm missing about the difference between the sintered and the tuning rotor?

But it will if you change the front endbell to part number 5917: http://www3.towerhobbies.com/cgi-bin...?&I=LXWLV1&P=7

If you already have the 5MM shaft rotor in your motor you already have this new endbell and the 14MM rotor will fit.

Yep! That's the endbell I installed.

Hmmm.........I don't see why the 14mm wouldn't fit, since the sintered rotor fits and works well.

As I understand it, it will probably "fit", but when we updated the HV motors other dimensions were changed that could create other issues with performance.

But, then, if yours works----it works!