Hello thank you for all remarks.
Yes i have both Z-Motors on the same controller, you have to use a additional heatsink on the Stepper IC and it would be
better when you use also a fan. I have heatsinks on each Stepper controller assembled.
Now i have to print a new case for the electronic with a cooling fan inside.
For the sync of both Z-axis, this is not a problem because they are on the same controller.
The only thing you have to do is measuring the alu-profil height (where the Extruder is mounted) on the left and the right side.
Also you have to check that both spindle are going free from beginnig to the end. Otherwise maybe one of the motor could lose some steps.
I had to modify the firmware because i use TR8x1,5 Spindle. The old M8 Spindle is 1,25 per rotation.