Some late model 4L80-E pistons have a darker appearance (similar to black oxide) and are not chrome plated in the bore area. Since removing the original friction material by a chemical or water jet process will not provide the surface finish necessary for a good bond, these pistons require machining (resurfacing) prior to bonding.
While Sonnax makes every effort to ensure the accuracy of technical articles at time of publication, we assume no liability for inaccuracies or for information which may become outdated or obsolete over time.