I mixed 2 sets of 993 steel gears I bought at a deep discount, non matching intermediate shaft & crank gears. I patterned the gears with marking compound just to see and measured backlash at four points with perfect results. Backlash was much better than any ALU gears I’ve checked. They have been in the engines 10 yrs with no problems.
One set went into a race engine with factory scatter oil filter that was always full of ALU filings, probably because of heavy valve springs. After installing the steel gears no more ALU in the filter. Just my observation.
