Unsolved Please help me with changing the wheelbase on my meshslap

I need help with changing the wheelbase on the meshslap mod im making and i just dont understand how im supposed to change the wheelbase! This is my first time doing this so im kind of proud of what ive done here so please dont ruin it for me lol.
(Its based on a different mercedes w210 mod)

 

have you figure it out yet?

 

suspension Jbeam