The Crawler Store offers some great adjustable motor mounts made by Thunder Tech. They sell for $29.99 and some with everything you need (pinion gears sold separately) to fully adjust your motors for a 9 tooth pinion setup.

The mount kit consists of slotted motor mounting plates and all the hardware required to make it happen. We did add some small washers to the lock nuts on the motor mounts however as we felt it would take some stress off the axle case.

Note: When mounting the pinion gears, you can not slide them fully onto the motor shaft. If you do, the pinion gear set screw will chew on the axle drive gear (this is bad). Take your time on this step to get them positioned correctly. Our setup had the pinion gear mounted several millimeters past the end of the motor shaft. There is still sufficient surface area...just make sure you mount the pinion set screw against the flat part of the motor shaft for optimal holding strength and apply some blue thread locker to the pinion set screw as well.

The front and rear Clod axles are the same. The rear axle is turned 180 degrees (backwards) when compared to the front. Because of this, you will need to reverse the direction of the rear motor so it turns the same direction as the front motor. If we lost you, just trust us. You have to do this step!

This is a simple thing to do. First, disengage the brush springs from the end cap and pull the brushes out slightly, just enough to move them away from the comm. Remove the two phillips head screws that hold the end cap on, spin the end cap 180 degrees and reinstall the screws. Slide the brushes back into the end cap and reinstall the brush springs. It is also a good idea to take a permanent maker and make a "R" on the motor label so you remember which one is reversed.

There are several options for an ESC in a Crawler. You should take into consideration the motors you will be using, the number of batteries you want to use and your budget of course. Many people use the Novak Super Rooster or the Traxxas EVX ESC as they are readily available (Super Rooster is discontinued by you can still find them). We searched around and ultimately decided upon a Novak XR Super Duty. It is a killer ESC, can handle lots of volts and truthfully is a little overkill for this project. The only bad thing about it is its size. It is a big unit and narrowly fit into our chassis (we actually built our chassis wide enough to handle it...just barely).

We modified the ESC to run on one battery (steps are included in the Novak instructions) as we plan on running a single LiPo, 3-cell battery in it initially. Next it was time to wire up the motors. We chose to wire our rock blasting beast via a parallel connection to the motors. A simple "Y" connection at the ESC splits the power to the front and rear motors. We soldered in a Deans Ultra Plug at the "Y" so we could unhook one plug and detach the ESC from both motors. It can be argued that you should not use plugs between the ESC and the motors for resistance issues etc but we wanted to try it from a convenience standpoint.

We "cheaped out" on this step and just used an old Traxxas T-Maxx AM receiver we had stashed in our parts bin. It should work perfectly as it has a third channel which we will use for the rear steering servo. This also works well as we are going to modify a Traxxas TQ3 transmitter (stock T-Maxx) to control the rear steering of our truck (see below).

There are two common options available for battery power. NiMH or LiPo. We chose LiPo power as we wanted the battery mounted on the chassis for a cleaner look, rather than having it mounted to the axles. LiPo's are so lightweight, the center of gravity would be affected very little by mounting it in the main chassis. In fact we designed the battery mounting area large enough to hold two 830 LiPo batteries so when one dies, we can just plug in the other battery and keep going. The leads are long enough that we can easily charge the batteries in the vehicle without removing them.

Yet again, we cheaped out and used batteries we had in our stash, two Apogee 3-cell Lipo 830mah bad boys. We were fairly certain the 830mah would leave us with short run times (two motors and two servos sucking lots of power) however we thought it was worth a try! At the very least, it will give us an idea on how many mah's we need to upgrade to in the future in order to get the run times we want. Example: if the 830mah lasts 15 minutes, a 2000mah should last about 35 minutes.

When using LiPo in a truck like a rock crawler, you really need to pay attention to the following things:

1. As soon as the truck starts losing power, stop using it. You do not want to go less than 3 volts per cell on the discharge side. If you stop immediately when the truck starts to slow down, you should be fine.

2. Avoid stalls. This is hard on any battery. When the truck "stalls" meaning the tires are wedged or otherwise rendered stuck and you are pouring the juice to it, it can short a battery. If your wheels get wedged, lay off the power and get your truck unstuck!

3. Keep the battery well protected . This is especially important with Lithium batteries. They are physically more fragile than NiCD or NiMH cells and need to be well protected from sticks or other foreign objects you might run into.

Note: We also have some IB 3800mah NiMH cells that we will be using in our XXX-T and then will use in our Crawler. They should work great The 6 cells will be split into two 3-packs and mount one pack on each axle to keep the weight low and even. Stay tuned for this modification at a later date.

Click here to check out STAGE 8 of Project Rock Ripper.....Body and Finish Work.