Chain drive conversion

On the original 503 with the very first chain drive, we ran 520 chain. Never had a failure of the chain, but it wore out too fast with the 600's. Thats why we went to the 530 chain. Also the 520 chain is narrower than the 530 and the gears I buy had to be modified in width to run the 520, the pitch is right the gears are just to wide. So the gears wore out within one season and the chain stretched fast. We decided it was worth the extra money to go with the 530 and have them last MUCH longer. Also there was less work in modifying gears so the 530 is a better option. Unless you can find gears that are hardned that are the right width they may last longer, but you would still be looking at faster chain degridation.