Are you pulling up to every red light in your stick shift modern Dodge Challenger and thinking, “Stop, hey, what’s that sound?” There’s something happening here and what it is, in fact, is exactly clear thanks to American Powertrain (AP).
That slight rattle or chatter in neutral at idle with the clutch engaged in anything equipped with a Tremec TR-6060, TKX, or Magnum transmission is actually easy to explain with some basic knowledge of how these manual gear boxes are designed.
According to AP, the short version is that the noise can be attributed to backlash (or clearance) between gears on the countershaft. This clearance is necessary to allow for proper meshing. If it did not exist, gears might jam or wear prematurely.
Tremec transmissions are built with large gears that are sometimes straight-cut or semi-helical. Those features make them incredibly strong, but also more susceptible to torsional disturbance which is the irregular vibration produced by an engine’s combustion events. Basically, torsional disturbance plus clearance between gears causes an audible chatter.
Torsional disturbance is more pronounced in powerplants with fat, fender-shaking camshafts. Lightweight clutch and flywheel assemblies also play a part since they don’t dampen those pulsations like heavier components would. Similarly, incorrect fluid selection can allow more clatter than normal.
Keep in mind that some level of chatter is a result of the design and nothing to worry about. However, minimizing its intensity is important both for the life of the transmission and your own sanity. We’ll go over methods to reduce the rattle in next month’s installment.
