Hmm I can't replicate this at all, can you send a blueprint or small world with the problem.

I downloaded the mod, reinstalled it, and tried again.Same thing. I'm running locally offline. No internet so I can't share a blueprint.

They seem to work fine with nothing on them. I put 3 rotors in a t-shape for the script and put 20 solar panels on the horizontal ones.

Without the script, testing them, no matter what speed I set they move extremely slowly with inertia tensor on. If I turn inertia tensor off they whip around real fast and won't stop until they slow down on their own no matter what I set speed or braking to.

Tested vanilla rotors. They work fine.
Tested these with Isy's solar alignment. Panels don't move at all.

Well I did it like this, this is the vanilla rotors one and the one with my mod is identical: https://i.imgur.com/Zt4Ydwm.png

It starts shaking and clangs into madness with shared tensor off, so that's probably what you're seeing when you're saying it spins fast? I dunno, either way, it happens on both.

And with it on, I have to wait for it to calm down before stuff works properly, but they both spin and stop just as fast.

I've not tried the PB script but I'd like to avoid complicating this test if possible, and so far it doesn't seem to be neceessary to clang the entire thing regardless of what rotors I'm using.

No clang no smoke no shaking, the mod rotors don't want to move with inertia tensor sharing on. Turn it off they spin out of control no clang no smoke no shaking no destruction. Vanilla rotors work as they should here. Thanks for trying. I'll just not use the mod and redesign the build using large grid stuff.

But you said vanilla ones work fine... why not use those? They're the same size, they just don't have conveyors.

It doesn't sound like you compared with the ones I'm comparing with xD a world would be the way for me to reproduce this properly... you can zip the save (%appdata%/SpaceEngineers/Saves/) and use a file sharing site :}

Vanilla's wont work for the plan I had. I wanted to build a not-insanely-large satellite I could place stationary in space to relay signals for various drone ships. I wanted conveyors on it so it had turrets to defend it self from meteor showers and if SPRT decided to attack it.

I never knew or realized a small grid advanced rotor that fits on small conveyors didn't exist. I had just about everything but the solar panels built and working really well before I realized this. It's a shame how there's always something in this game, that's ridiculously stupid, disappoints.

What a bummer...