We have this setup and the crew is fighting an issue of a consistent vibration at contract speed. If they put a few hundred pounds in car it goes away. This vibration is there in openloop or closed also its there if you just drift the car up by picking brake. There vibration isn't there during decel or acceleration. I'll be on-site tomorrow morning to help out diagnosing. We are leaning toward possible machine issue. This Is brand new mod. I'll go through the basics, encoder, parameter setup ect. What say you??

When you have vibration when drifting the car up by picking the brakes, you don’t have to waste your time checking encoder or drive parameters. Focus on mechanical issues only. I would check the rope tensions and make sure they are equal, and also check the gearbox if its a geared machine.

Kinda what I'm thinking, but need to verify.

It would make sense for it to be mechanical from what you described. Especially since it's not there during acceleration or deceleration when the forces and weight is shifting momentum and for a brief time cause whatever is causing the vibration to not be under load but then as the speed levels out it comes under load again.

Did yall have to disassemble/reassemble this machine to get it in the MR?

So we did adjust gearlash, that had minimum improvement. The vibration is a high frequency. I also turned off inertia, the vibration would go completely away if we did this and slowed car down 50fpm, 350 down to 300. So that's where it sits currently.

Please check four points.
1. Check that the encoder wires are running separate from other wires.
2. Check whether the encoder is tightly fitted in position. Dismantle and refit it again to check the integrity of the encoder and fixing plate. Sometimes if the fixing plate base is loose this can happen.
3. Check that the machine is in level, and that the nuts used for the rubber sound isolation pads aren't tight. These should be hand tight and shouldn't be compressing the rubber pads.
4. Check that the load switches come in correctly. If your load sensors have bottomed out, or if you have friction in the car frame and the cradle housing the switches, you can have improper feedback affecting ride quality.
I hope these simple actions resolve your problem. Kind Regards
P.S. I just read in your post that when you put load in the car the vibration disappears. Please check the first set of load switches, probably it is activating on empty car and giving feedback that the cabin is loaded when it is not, and when the load is introduced, it works correctly. I don't know whether you are using a strain guage or physical switches for each load. You will have to recalibrate the load switches accordingly based on the system in use.