J&J Racing, Ltd. 103 South Church St. Bally PA 19503   610.845.2848  FAX 610.845.8820 

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"When a transmission is on our dyno, utilizing infrared pyrometers, we monitor temperature at a minimum of 12 key areas..."

The purpose of the gear box dyno is to accurately measure power loss to the wheels due to drag in the gearbox. Many shops attack the obvious culprits of drag: heavy differentials, stock crown wheels, heavy oil, etc.. Although these are all valid points, they are only the tip of the iceberg. We have found through years of dyno testing, on a multitude of transmission makes and models, that a large percentage of drag within the gearbox lies in misalignments of shafts and bearing bores at operating temperature. For example, a bearing misalignment of as little as .004" substantially increases drag and temperature. One of the keys here is operating temperature.
When studying the gearbox drag and temperatures on a dyno run, at factory recommended pre loads and settings, there are sometimes significant drag and temperature increases. Keep in mind that the aluminum or magnesium cases, side covers and internal steel components of these gearboxes expand at different rates while temperature increases.
This is due to the size, material and mass of the particular part, internal & external webbing in the case and side cover design. Another key issue we have found is the distortion and movement of left hand side covers under load. It is important to locate the side cover for optimum bearing alignment at operating temperature under load.
When a transmission is on our dyno, utilizing infrared pyrometers, we monitor temperature at a minimum of 12 key areas. This allows us to see potential drag problems in the gearbox before we ever take it apart. Once the gearbox has been completely blue printed to our specifications we are able to run the gearbox again on the dyno to document the decrease in drag. In addition, this is also a useful quality control tool to insure that the gear box runs properly in all gear selections and has no leaks.

We would be glad to answer any questions you may have about your gearbox. Please contact us for information on the services mentioned above as well as gearbox rebuilds and gearbox blueprinting.



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