WHEN talking diff centres the terms high- and low-pinion can come up in conversation. If you’re not familiar with the terms don’t be too embarrassed, as they’re irrelevant in 99 per cent of situations. The purpose of a diff centre is to redirect drive running down the vehicle, and to send it out to the wheels. It does this by running a pinion gear along the side of a crown wheel (or ring gear). High-or low-pinion simply indicates whether the pinion gear connects on the top or bottom half of the crown wheel.