What is a limited-slip differential?

A limited-slip differential (LSD) is a mechanical part usually found on performance cars to help them corner better. Regular 'open' differentials allow the wheels on an axle to both receive engine power while spinning at different speeds. This is necessary while cornering because the outside wheel has further to travel.

Open differentials work fine for normal cars during normal driving, but aren't as desirable when driving on a race track. Here, open differentials waste engine power by spinning it away if either wheel loses grip with the road – usually via the inside wheel while cornering.

Using clever mechanical principles, a limited-slip differential will gradually resist the wheels' ability to spin at different speeds, eventually locking their rotation together, which you'll feel as extra traction while accelerating hard out of a corner. Some modern performance cars replicate the function of a limited-slip differential with a regular open unit by individually braking the wheels on either side to stop them slipping and wasting power.