You would be surprised as many people believe that both drive wheels are connected and always spin at the same time. If they were correct imagine a car taking a corner, the inside wheel would be spinning slower than the outside wheel. In theory it doesn’t sound that bad until it’s tested out. Imagine every time you turn, even at low speeds, there would be slight wheel spin from the outside wheel causing noise and wear to the tire. Not only would it make noise are ruin tires, it also would create a lot of stress on the drive train as it would always be binding during turns. It was not long before this was out of the question and the open differential was invented.

The picture above demonstrates an open differential that is the most basic of them all. The driveshaft spins the ring gear which is connected to the side gears. They both spin at the same times which then make the spider gears that are connected to the side gears spin. The spider gears are connected to the left and right axles which connect to the wheels. With this setup you can have one wheel spinning faster than the other while still pushing the car along the way. This setup even lets you stop one wheel completely and only allow the other wheel to spin. The reason why this setup fails is because if you for example put one wheel on ice and the other on pavement, you will not be able to move as the wheel on ice will only spin. The reason for that is since the differential is open the wheel with the least amount of effort to spin will get all the power while the other wheel just stands there. This setup believe it or not is still on the roads today, which can be ok to use in a very regular car, but if you want to go off road or do sporty driving it quickly shows its drawbacks.

The clutch type LSD has a set of small clutches on each end of the axle that are engaged by a spring system in between all the gears. As one wheel spins faster than the other the spring pushes on the clutches connecting the left and right wheel together tighter and tighter until they lock. The great thing about a clutch type LSD is that you can change the order of the clutches to change the percentage of the engagement point when you want to wheels to lock up.  For example: at 60% or at 80% if you’d like. The downside to this differential is that it requires frequent oil changes,  makes a lot of noise and eventually the clutches wear out making it turn into an open differential. This is the perfect setup for the track as it is very adjustable and gives excellent results for auto cross, drifting, road racing, and even drag racing. It is usually found as an aftermarket differential that is available for most cars. The added maintenance is a small price to pay for the performance this kind of differential delivers, but if you would like something that is more for street and longer durability the next type of LSD will satisfy your needs.

The next type of differential is the gear type LSD. This LSD is found in many of the cars on the road out of the factory. They are nearly silent which, makes them great for production cars and there is almost no maintenance necessary.  This allows them to come with a lifetime warranty! The downside to this kind of differential is that it is not adjustable and does not actively transmit between the axles, but rather using worm gears to multiply the torque from the slowest wheel to the fastest. This makes the gear type LSD good for the street but not as effective as the clutch type on the track for hard road racing or drifting.