Case Studies - Chain Drive Differential

Mark Jeremko in his WRD equipped Stohr WF1 DSR (photo: Sharlene Plescia, Ghostcars.net)

WRD-CDD-1000

Luxon Engineering was approached by Lee Williams of Williams Racing Developments to design and develop a new chain drive differential. Lee wanted to use his modified salisbury differential in a chain drive application to provide a high performance alternative to his customers. This differential is designed to be a drop-in replacement for the Quaife style differential commonly used in D-Sports, C-Sports, F1000, and other chain drive vehicle applications. Lee gave us the following design requirements:

• It must be a drop in replacement for the Quaife style differential already on the market
• It must use WRD's modified Salisbury internals
• It should be as lightweight as possible
• It should be relatively economical to manufacture
• The end result should be ascetically pleasing

(click on the thumbnails below for a larger view)

Design

With the above requirements in mind and working closely with Lee, Luxon Engineering began the design of the differential. A few design concepts were thrown around until the final concept was decided upon. From there, analysis was preformed and the proper documentation was created. See the sections below for more on these steps.

Analysis

In order to achieve a lightweight design capable of enduring the loads seen in racing, multiple finite element iterations were preformed to arrive at an optimized design. The results of the sprocket mount analysis can be viewed by clicking on the thumbnail. All highly stressed components in the differential assembly received the same analysis treatment to ensure adequate strength and fatigue life of the final design.

Documentation

Because this design was intended for production, full documentation was necessary. This includes a complete Bill of Materials (BOM), toleranced drawings of parts, assemblies and sub-assemblies, memo's and justifications, and renderings of the design. Click on the thumbnail to the left to view the installation drawing (pdf) provided to WRD's customers. A memo detailing the justification of the drive system and its structural capabilities is also available (pdf format).

Testing and Results

After the initial design was complete, prototypes were made for testing. Throughout the testing the design was perfected to arrive at the final production configuration. Typical weight savings over competing products is 4-5 lbs (rotational weight). Back to back testing of the WRD differential and the Quaife style differentials show that the modified salisbury design of the WRD differential increases turn-in performance and nearly eliminates inside-rear wheel-spin on corner exit. This allows the driver to get on the power sooner, resulting in substantially faster lap times. For more information about this product visit the Williams Racing Developments website.

Cole Morgan in the WRD equipped Stohr F1000