Clutch liner Presoaking

Clutch liner presoaking revealed to be beneficial Recently, Dennis Sneath and Clayton Balhms of one of the nation’s oldest oil manufacturers discussed the pros and cons of presoaking a converter clutch liner in ATF is necessary prior to installation.

It has been brought to many rebuilders’ attention that presoaking a clutch liner can be a preventative procedure before shipping to ensure proper saturation of the friction liner is attained. Under normal circumstances proper saturation requires 20-30 minutes of presoaking to prevent premature liner failure.

While this debate has existed for many years in the industry, Balhms reassures this step is critical for proper converter rebuilding. He suggests adding one pint of ATF after the completion of the torque converter, and sealing the unit with a plastic cap prior to shipping. As an added benefit, ATF absorbs water vapor that is left behind after the rebuilding process.

Before the converter is installed into the transmission, it is also suggested to add one quart of ATF into the converter. This helps to prevent the stick-slip syndrome of a dry start on clutch engagement. The process of converter clutch lubrication is quite complicated.

At first start up, the clutch plate is in a neutral state, separated from the front cover by hydrodynamic lubrication. This is the same type of lubrication commonly found in an engine between the rod bearings and crank shaft. Hydrodynamic lubrication depletes as clutch application starts. Boundary layer lubrication is achieved. The ATF viscosity increases as the layer is compressed. As the lubrication film layer starts to shear, near contact is achieved between the clutch liner and front cover. The engagement between the clutch liner and front cover begins as the oil is depleted and contact is completed.

If the clutch liner has dry spots from improper presoaking, or lack there of, clutch burning usually occurs causing small spots of degradation on the liner. Although damage may be minimal and undetected, the damage could be prevented by presoaking the liner.

The TCRA would like to thank Balhms for his contribution and insight regarding proper clutch liner preparation and installation. Balhms maintains a CLS degree in lubrication and has contributed to the design and manufacturing of many lubricants.