What you can do is remove the center drive shaft then stick a 2mm driver into the slipper. Hold down tight and roll the car forward(keep pressure on the driver, it will try to spin). Keep going until the tires lock up. After that happens roll it backwards until the tires just start to spin. That's what I did with my Big Rock. Since I installed a new pinion in my Vorteks, I adjusted it manually since I had the whole motor out.