Building a 4" Scorpion II Chassis

Begin by checking the individual sections of the chassis for straightness.  It is necessary to check a new chassis too.  Often they are bent right out of the bag.  Place them on a small piece of glass (you can use the back of your tech block) and tweak until each section is flat.  Take your time and do a good.  Remember, you are building the foundation of your race car.  Taking your time with this step will pay big dividends on the track.  If you are rebuilding a used chassis, remove all old solder and clean the entire chassis with a good cleaner.

The Next step is to install the axle bushing.  Install the bushings into the chassis.  Insert an axle and use two old wheel hubs to hold the bushings in place.  Using a dial calliper, check the distance from the top of the axle to the bottom of the chassis on each side.  Use a dremel tool to raise or lower one hole on the chassis to facilitate alignment of the bushings at equal heights.  (Most rules allow for minor adjustments in this area.  Major modifications beyond those necessary to align the bushings are illegal under most rules)  Once the bushings are aligned, Solder them to the chassis.

T e c h      N o t e b o o k

Once the bushings have been soldered into place, use a pair of pliers and an axle to adjust the bushing alignment relative to the axle.  The objective is to remove as much friction as possible.  When properly aligned, the axle should fall from the bushings when the chassis is turned on its side.

The next step is to assemble the chassis.  Begin by installing the screw and nut assembly.  I recommend using the second hole for the shorter wheel base.  I leave a slight amount of play.  Next, install the front axle and solder it to the chassis.  I use .063 piano wire and cut it extra long.  It can be cut to size later.  The final step is to install the piano wire which supports the rear of the pan (don't forget to install the lock collars).

If you choose to install the lock collars on the outside of the center section of the chassis (recommended), it is necessary to solder the piano wire to the pans.

Here, the front axle is soldered to the chassis.