Chassis and Running Gear
by Bob Ward
Every custom slot car body deserves a good chassis. That includes, of course, a chassis that fits it. Here’s a simple but effective chassis for my CanAm kitbash project.
Here’s the chassis for the Frankenwedge. Many of my readers will recognize it as a chassis I’ve used in car builds before, a Fly Ferrari 512S sidewinder rolling chassis with modifications. As I always do with Fly sidewinder cars, I replaced the gears with Scalextric ones, the W8200 pinion and W8201 spur. The rear wheels are from an old Fly Porsche 934 rear axle assembly, modified with inserts from Fly Renault 5 Turbo wheels. This particular combination is not always available, but the Fly 04403 Porsche 934 rear axle assembly with BBS wheels has the same dimensions, and most people will probably think the BBS wheels look better. The rear tires on the car are Indy Grips 3008 silicones. At the front I used wheels and tires from a Carrera Ferrari 512 BB, but if you use the Fly 934 BBS wheels at the rear you can use matching front BBS wheels from a Fly B95 or 04402 axle assembly. Before ordering these Fly axle assemblies, check with VLH to make sure the centers match front and rear, either a silver or a gold color. Fly changes part colors and finishes from batch to batch without changing the stock number.
The two most challenging mods were moving the entire pod assembly .060″ forward in the chassis to make the wheelbase match that of the body and modifying the pod to accept a Scalextric, Pioneer, Slot It or Professor Motor bar magnet. The bar magnet upgrade, as I’ve described in previous car build articles, greatly improves the drivability of any Fly classic sidewinder car by providing magnetic downforce over more of the car’s width than the stock Fly cylindrical magnet does. Also, by using your choice of these bar magnets and shimming them by different amounts you can adjust the amount of magnetic downforce to give you a wide range of grip levels and driving characteristics.
This photo shows what is involved in moving the pod forward. Compare the unmodified chassis on the left with the modified one on the right. The first step is to lengthen the rectangular opening of the front pod mounting point by .060″ toward the front of the chassis (red arrow). Next, cut off the cylindrical rear pod mount flush with the top surface of the chassis and slot the screw hole .060” toward the front of the chassis (blue arrow). You will be using a machine screw through both the chassis and the pod to hold the pod in place. Depending on the size screw you use you may have to widen the slotted hole, also. I used a 4-40, so I did have to make the hole wider, as you can see in the photo.
The next step is to glue a spacer of .060″ thick styrene in place to positively locate the pod the desired distance forward of its original position. After this photo was taken I painted the spacer black to match the rest of the chassis. The chassis was then ready to install the pod.
But first I needed to modify the pod to fit into its new location and to accept a bar magnet. In the above photo an unaltered pod is on the left, a pod with just the bar magnet modification is on the right, and the pod used on the project car, modified for both the bar magnet and relocation in the chassis, in the center. In order to move the pod forward I had to cut the forwardmost bar off the bottom of the pod as shown above. That can be done easily with a hobby knife. You can also see that on the completed pod I’ve shortened the tab that goes into the front pod mount. That is necessary because I’m moving the pod forward in the mount. The tab is still long enough to hold the front of the pod securely in place.
Here’s the rig I use to machine the channel for the bar magnet into the pod. A Dremel Moto-Tool is mounted into a stand, also made by Dremel, that allows the Moto-tool to be used as a vertical milling machine. A piece of sheet brass is clamped to the side of the unit to provide a guide along which to move the pod for cutting a straight channel for the magnet.
Here’s a closeup of the cutting tool and the modified pod. The tool is a high-speed steel cutter, .300″ in diameter, available anywhere Dremel accessories are sold. This tool cuts a channel just wide enough to take the widest of the bar magnets I use, the ones made by Professor Motor. Scalextric, Pioneer, and Slot It bar magnets are slightly narrower and require some layers of tape on them for a snug fit. I set the depth of the channel a bit deeper than the thickness of the thickest magnet I’m likely to use. This allows me to set the magnet height for the desired level of downforce by using a magnet that generates more than the required amount when placed right on the surface of the chassis and then shimming it upward to get the exact figure required. Setting the desired magnet downforce may require shimming both above and below the magnet. By the way, this modification does not prevent the original Fly cylindrical magnet from being used if required for a particular race. There is still enough of the original magnet socket left to hold the round magnet in place. I’ve found that when shimmed enough to be captured tightly between the pod and the chassis the bar magnet will not move from side to side, but if desired there is nothing to keep you from gluing in short lengths of styrene strip next to each end of the magnet to ensure proper location.
Here’s the completed installation. You can clearly see the .060″ spacer and the machine screw with its nut and lock washer. You can also see the Scalextric gears installed in place of the original Fly gears. Also visible is the end of the bar magnet peeking out past the edge of the pod. Note also that the motor has aftermarket silicone-insulated lead wires installed. The entire rear axle assembly shown here is made up from inexpensive stock replacement parts for various 1/32 scale cars, but of course there is nothing except cost to prevent you from using high-end aftermarket parts including brass or bronze bushings, a drill blank axle, and set screw spur gear and wheels, especially if you are going to race without a magnet.
So here it is, the completed Frankenwedge. As with all my project car articles, I have attempted to present ideas and techniques you can apply in building models of many different cars or in bringing to life your own original creations. If you have any comments or questions on this article please send them to firstname.lastname@example.org. I will be glad to help you with as much information and advice as you can use. And if you have a completed car project you would like to show to the world, the VLH staff invites you to send us information and photos. You may see your creation in our newsletter or on our web site.
Copyright © 2013 Robert M. Ward. All rights reserved.