Originally Posted by Dave Severson
Main reason there aren't as many problems on the distributor gear is that these gears are beveled gears, not straight cut gears..
As for proof of the damage caused by gear drives.... We used to run the Pete Jackson gear drives before the good double roller chain sets came out in our racing engines.... Had a lot of problems with valve trains, and strange wear on cam bearings and other valve train parts. We switched to the Cloyes double rollers when the came out, no more valve train or cam bearing troubles... Is this proof? Probably not. Just an observation.
Basic engineering will show that the chain will abosorb some of the vibrations, straight cut gears do not. If anything they amplify them.... The gear drives do not make timing more accurate then a high quality chain. All they really do is make noise.... To some I'm sure this noise is kewl.... To me the noise is just going to drown out any small ticks, clicks, or whatever's that I will never hear over the gear drive....
Sometime, on a car with a gear drive, when it's running put your fingertips on the timing chain cover.... You will feel some very strong vibrations... These vibrations (harmonics) will do nothing to improve performance in an engine...