I have a gearbox with a spur and pinion gear which has helical cut teeth. I can get the spur and pinion gears with either a LH or RH helix. I would like to increase the centre distance between the input and output shafts. Can I use a second pinion gear to act as an idler gear between the original spur and pinion? ie. currently LH pinon >drives> RH spur change to LH pinion >drives> RH pinion >drives> LH spur If this is possible does this mean any gear must be capable of mating with itself (helix angle reversed)? How do I determine the correct centre distance between the two spur gears given that I know the centre distance between the spur and pinion in the original design and the gear PCDs ?