There is absolutely no effect or damage causes by Pmax Black to the journal surface.
Pmax black bearings differ from the competitive bearings due to a special surface treatment of the overlay. The treatment produces a strong ultrathin (nano-scale) skin which inhibits formation of fatigue cracks. Therefore load capacity of Pmax black bearings is at least 17% greater than that in the competitive racing car bearings. Hardness of Pmax black overlay is also higher than that of the competitive overlays (by 24%).
The value of hardness 18 HV in comparison to 11-14HV of competitors is still low enough to provide excellent anti-friction properties of the bearings (embedability, conformability and compatibility). For example hardness of aluminum alloy in bi-metal bearings is about 40HV.
The extremely low (nano scale) thickness of the hardened surface layer of Pmax black bearings guarantees that the journal surface can not be damaged (scratched) during metal-to-metal contact. If direct friction occurs the surface shield wears off from the overlay surface producing no scratches on the steel surface.
The effect of direct friction between tri-metal bearings (surface hardened and non-treated) and steel journals has been tested in King Test Rigs. The results proved total indifference in regards of the journal surface damage between the treated (Pmax black) and non-treated bearings.
