I found a fix for the immovable cockpit issue that many are having at least this is what is working for me.
In order to solve this problem, you need to download the 4.1 version of "Flan's mod".
Then open the version 4.1, go to the folder co / uk / flansmod / common / drivables and find a file called entityseat.class. Next open the same folder in version 4.1.1 in the B-team folder and copy entityseat.class in this version.
Now you can put the modified version in the folder with the mods and play without bugs.
Sadly my post kinda got ignored its already in the forum :/
Well have fun ^^