The slipper on the XX-4 off-road car can be tough to get tight enough on certain track conditions. Under high-traction, bumpy conditions the plastic spacer (key number 19 in the XX-4 manual) that is located next to the bearing in the slipper assembly can take a set and keep the slipper from being fully tightened. The result is usually a melted belt pulley due to the excess slipper heat caused by the slipper constantly slipping. A simple solution is to add two thin 3/16" shims between the spacer and the bearing on the slipper assembly. This will allow the slipper nut to fully tighten the slipper. The tighter adjustment will keep the slipper from slipping excessively and help prevent the belt pulley from melting.

The one-way/clicker assembly on the XX-4 is very cool! It allows the front braking force to be adjusted anywhere from virtually non-existent to fairly heavy. If you’d like to have even stronger front brakes,there is a way to increase the front braking force even more.To do so, remove the small adjustment nut from the one-way/clicker assembly. Next, remove the spring spacer and clicker spring. Carefully (you don’t want to drop it inside and have to take your car apart) place a rear axle spacer over the shaft and align it so that the spacer is centered on the shaft around the portion with the flat sections. Place the spring spacer over the shaft, next to the axle spacer and tighten the adjustment nut against the spring spacer. The one-way/clicker should now be locked in place. The result is full-time 4WD and full braking force to both the front and rear wheels.