I recently reviewed the second released series of cars by AMT in their Slot Stars line. AMT had taken a step back and looked to improve on their first release and made major improvements in the rims, gears, motor mounts and axle spacers. These new parts were significant enough that I thought a step by step assembly article would benefit those racers looking to try these new slots out.
Let me start this off by saying these are not simple kits. Although the parts are easy enough to put together, these kits are more akin to the old K&B “Build A Car” components that were sold in the 60’s. It takes me about one hour to assemble and adjust one of these AMT kits. I take my time, test fit the parts and then measure, mark and assemble. It’s a bit slower method, but I would rather spend the majority of my build time making speed and handling improvements, not getting the base pieces together. These are nice kits and the parts are well made and fit together properly. So let’s start out by seeing what comes in the kit.
I will be focusing on the chassis and its components and not so much the car body itself, with the exception of measuring the wheelbase on our example chassis. I’ll also be showing some alternate body mounting options and some break-in/tuning suggestions.
Phase 1: Getting the Wheelbase Set Up
Gather up the following parts: the front and rear chassis parts, the lower body mount bracket and 2 screws, washers and nuts. Fit the front and rear chassis components together, along with one of the lower body mount brackets. Test fitting these together, place one of the screws in the rear screw hole on the rear chassis, the slot of the front chassis and the slot of the lower body mount bracket. Add the washer and nut, but do not tighten completely. Repeat this step on the opposite side of the chassis. You should be able to slide the front and rear chassis pieces to various wheelbase lengths and should look like the picture above.
Still in the initial set up mode with the screws loose, the lower body mount bracket should look like this, on top of the chassis assembly. If placed below the chassis, it will drag the track.
Next we take the body we are building the chassis for and slide the chassis sections until we line up the center of the axle holes with the wheel wells like the picture above. We are using the ‘66 Olds 4-4-2 for our example. Once you have the length where you want it, mark the bottom of the chassis where the two halves come together. That will assist in keeping everything in position when you tighten down the screws. I use a piece of electrical tape to mark the chassis. It’s easily visible and I can reposition it if I need to change it (see below).
Once you have the position marked and you have measured twice to be sure, tighten down the first set of screws you have in place and then add the second set on each side. You should have something like this (below). These are small, fine threaded screws and nuts, so don’t over torque them. They just need to be tight enough to hold the parts together. One note, if you are not using the body mount brackets to secure the body to the chassis, you can bolt the chassis halves without the body mount bracket in place.
The next step is to complete the body mount bracket assembly. Take the upper body mount bracket and align it to the lower unit that is bolted to the chassis. This assembly can be adjusted to narrower or wider positions to adapt to various bodies. If you are using the double sided tape to secure the body to the chassis, remember to leave about 1/8th of an inch from either side of the body for the thickness of the tape. Your chassis should look like the pictures below. You can skip this step if you are not going to use the body mount brackets.
You now have the base chassis assembled and we will start on the motor and running gear. First we will take the motor mount bracket and place it on the metal end of the motor can and secure it with 2 screws. Make sure to do this step before you install the pinion gear as the gear will not fit through this mounting bracket. The bracket acts as a spacer between the motor can and the chassis mount point for the motor. See the assembled motor below.
Once the bracket is installed you can press the pinion gear onto the motor shaft. A gear press or in my case some modified Channel-Lock pliers (it has hole for the motor shaft to pass through) can be used. Make sure to press the pinion far enough onto the motor shaft. You should have around 1/16th to 1/8th inch of the motor shaft coming through the pinion gear. This will place the crown gear teeth near the middle of the pinion gear for better mesh of the teeth.
Next we mount up the motor assembly to the chassis. Slide the motor into place and secure it with 2 screws. I keep in the habit of placing the side of the motor can with the lettering facing up. That way the wiring is in the same position for any of my future builds. Your motor and chassis should look like the pictures below.
Next we install the rear axle bushings. These just pop into place. Keep the flange facing the outside (towards the wheels) of the chassis. Slide the rear axle through with the crown gear in place. Center the axle to the chassis and slide the crown gear so it meshes lightly with the pinion gear and tighten the set screw on the crown. The axle will still move until we place the aluminum locking spacers, but this gets our crown gear into the right location for the next steps.
Now that we have the crown gear secured we will place the locking axle spacer on the opposite side of the chassis. That will allow us to set the gear mesh and to make sure we do not have any binding happening. Leave enough play for smooth gearing and then tighten the locking axle spacer in place as shown below.
Place the next locking axle spacer on the opposite side of the axle and tighten. Next we will place the rear rims and align them to the width of the car we are putting the chassis under. Once in place, tighten the set screws on the rims. Your rear axle assembly should look the one below.
The front axle is up next. We place the axle bushings in the chassis, then the front axle, centering it with the chassis. Lastly, install the front rims leaving a small gap for some play in the axle and to prevent binding. Tighten down the set screws on the rims. You can follow along with the next set of pictures.
Push the tires on to the rims and work them around so they seat within the flanges. Your chassis should look like the one above. Our next steps will cover the electrical connections and the guide flag.
But before get to that, let’s slide that Oldsmobile body onto the chassis one more time and check out the wheel alignment. (See below) Looks to be spot on…
AMT has also changed up the electrical parts for their second release. The guide flag is a new 2 piece unit with deeper slots to hold the braid. The braid is also a new assembly that will require some technique to get right. The “T” pieces shown below hold the braid and once bent to the proper shape, hold the braid against the motor wires inside the guide flag.
Take note on these next steps. It’s important to make sure you fold the “T” shaped braid holders as pictured below, so they will fit inside the guide flag slots. If you fold them too wide, the braid will not sit flush with the bottom of the guide flag.
Using a flat pair of pliers, bend the “T” shaped braid holder with a slight angle so the top edge at the fold is more narrow than the rest of the long side of the “T”. Only bend the “T” to 90 degrees (see below).
Fit the braid into the slot you created with the “T” shaped braid holder and position it halfway along the long side of the “T” (above).
Crimp the tabs you created over onto the braid on one side and then repeat for the other side. (above).
The next step will create the spring effect that will hold the braid inside the guide flag. Fold the long side of the “T” down over the braid and crimp at the top, at the bend. The gently pry the opposite edge up just a bit so the folded piece sits up away from the braid it covers. See pictures below.
Now we will wire the guide flag and get the braids in place. Strip about 3/8ths of an inch of the motor lead wire’s insulation. Twist the wire tight so in does not fray. Insert the motor lead wire into the top of the guide flag slot as shown below. We will do the red wire first. Then holding the wire in place, push one of the braid assemblies into the guide flag from below making sure the “T” retainer is completely flush with the bottom of the guide flag.
Leave Some Play So the Guide Swivels Easily.
Trim the Braid Back So It Does Not Contact the Chassis.
Before you fire this hot rod up, let’s make sure we get lubrication in all the right spots. Make sure everything turns freely and make adjustments as needed.
Make sure to apply oil to all of the pinion gear teeth
during the first break in phase.
I hope this helps you in building your AMT Slot Stars chassis. I really enjoy these and have found a few model bodies to expand my stable with, using these chassis as my base. I will visit the body mounting options in a new “How-To” article. Turns out there are a few good ideas out there and I would like to cover them in their own article. So check back here at Speed Inc.