How to prevent a rollercoaster cart shaking vigorously?

I've recently made a restraint system for a rollercoaster cart. It is worked by two different restraints, and when the button is clicked one goes transparent and the other doesn't, and vice versa, to give the illusion it's moving upwards.

Now, since doing this, my rollercoaster cart has started to shake vigorously, unlike it did prior.

The cart has weld scripts in due to the fact it cannot be anchored, nor can any part of it, due to the fact it then wont make its way around the track.

If anyone can help me to stop it shaking it'd be greatly appreciated.