As you can see here, I replaced the 5mm spider axle with an 8mm. On the drive axle, I replaced the one extra long linear bearing with two bearings that I could lock together. This allowed me to prevent the buckling of the axles from the tension of the timing belts. I only put a couple of belts to show what was taking place. before I go further, I may take a little time to choose a brushless motor that would best compliment the project