I'm sure most everyone knows this but putting it out there for anyone that doesn't. Ford and other manufacturers decided to use nylon timing gears for less noise. They were great until they got old and brittle. The GT500 i just picked up is a low mileage car that was never modified. As with any older car I purchase the pan gets dropped for a an internal inspection. The pan was clean but full on nylon chunks. The cam gear was missing most of its teeth and had a considerable amount of slack. If your engine has never been apart this is a good thing to inspect. They will run and start much better with accurate timing and eliminate the risk of sucking up a piece of nylon and jamming the oil pump. Just my .02 on this matter....
The customer is king. They wanted quieter cars - Ford (and every other manufacturer) delivered. They were cheaper to mold than machine out of steel and they outlasted the warranty so it was a good product. I had a Camaro that all the plastic teeth were gone so it was running on the aluminum. The timing chain was so loose it rubbed a hole in the timing cover and was spewing oil all over - it was a good buy for $150.
They still work fine for stock engines - but don't put heavy valve springs in. Roller chains are also junk. They take less horsepower but stretch far faster than the stock chains.
Besides noise reduction, imagine the cost savings also.
Plastic gears are generally less expensive to manufacture than their steel counterparts.
Millions of engines produced times the cost saving amount.
Plus the residual income of selling replacement parts and ofcourse incremental bay repairs.
Is a winning formula to continued success
Chi Ching goes the cash register full of CA$H MONEY !