AllStar Rug Doctor Dodge Challenger NFC Off-Season Report #2

In my last report, I discussed what we’ve been up to in preparation for next season.  Over the next several months as we reassemble the AllStar Rug Doctor Dodge piece by piece it provides me the opportunity to share with you the progress as well as insight to the more critical components that are key to the car’s safety and performance.  In this report, I’ll discuss a very important component that is normally hidden and often overlooked; the rear differential and housing.  

The differential and housing function much like a typical automobile differential or rear axle but have extra large internal and external components to handle the extreme loads from a nitro burning engine.  Our external housing is cast out of aluminum to save weight.  This type of differential is called a “top loader”.  Normal differentials have an opening in the front or the back to facilitate ease in assembly and maintenance; however those opening locations are in the worst places when the housing’s strength is critical.

During the launch of the car at the starting line, the two rear tires drive forward while the rest of the car and its weight which is attached at the center of the housing is resisting that motion “pushing” rearwards.  Under this condition stretching or tensile loads are across the back of the housing while compressing loads are centered on the front trying to bend the housing into a banana shape.

Having an opening in the specific areas where these forces are being applied creates weak spots allowing the housing to bend undesirably.  To maximize the housing’s strength the opening has been placed away from these locations, in this case on the top and hence the name “top loader”.  The described forces are most extreme at the launch but exist during the entire race as the car continues to accelerate all the way down the track.