How to speed up the 4x4 Crawler truck 9398? Just finished building the 4x4 Crawler and it was a fun build but as a remote control car it is . . . in a word . . . SLOW! I know it's powerful and can climb over stuff but sometimes there is nothing to crawl over and I'd rather it be faster. Are there any other gear configurations that would make it a bit more exciting?
The simplest way to get different speeds is by changing the gears. The instructions get you to build it with a 12:20 gear down in the portal axles, so the easiest way to change the speed is to flip those to get 20:12. From memory that will not work because it interferes with other parts of the model.

You can fit two 16 tooth gears in there instead, giving a slight speed increase. Or you can put an 8:24 gear down for even more torque (but even less speed). There two options are shown below.

It's important that you keep all four wheels geared the same, otherwise you will be making the front and rear motors fight each other. That's not great for the motors and gears, and it will drain your batteries very quickly.



Deeper inside the model there is another 12:20 gear pair that you can also swap for 16:16 (two sets of this, one each end).