Gadgetory

if two wheels are locked on an axle so that they are not free to turn separately one or the other as to slide so engineers had to find a way to connect both rear wheels to the engine without sliding and slipping on turns the device which makes this possible is a part of the rear axle it is called the differential because it can drive the rear wheels at different speeds now before we talk about limited slip differentials let's get a quick refresher on differentials here's one out of a vintage Alfa Romeo good because it's fairly simple and can get us down on the basics the idea about a differential is to allow the two in this case rear drive wheels to turn at different speeds while going the same direction that's important in let's say turning a corner where the outside wheel is going to cover more distance at the same time than the inside wheel it has to turn faster if it didn't do that either the inside wheel would have to slip or these gears in the middle would take a beating a differential allows these two to operate somewhat independently power comes in here from the cars drive shaft here turns this which operates a pinion gear that turns the ring gear which turns planetary gears which then turns bevel drive gears that turn the axles of the output shafts now here's where this whole assembly falls down as miraculous as it is if one of these wheels loses traction the power or the torque goes to the path of least resistance and spins that wheel the one that's not getting any grip well the one that does have grip sits there getting very little or no power that's just not a good thing so whether your car is slipping a wheel because of a poor surface or because of lifting during cornering or just because you're standing on it one wheels lighting up a standard or open differential tend to put the power in the wrong place when there's a lack of grip that's where a limited slip differential comes in it limits the slip that is natural to a basic differential if a drive wheel loses traction the differential sends power to the opposite wheel or axle with the best grip or the slower moving wheel or axle a front wheel drives have this same function but it's built into their trans axle transmission assembly on the front of the car now we could spend hours on the details of how these work internally but basically there are several types Gared differentials use spring loading and a more complex pack of gears than a standard or open differential like we have here clutch or plate limited slip differentials use those kinds of parts to engage one output shaft or the other based on wheel resistance if a wheel spins its clutch or pressure plates loosened to send it less torque viscous coupled limited slip differentials rely on disks in the differential spinning in silicone fluid that gets either Gravier or less so based on that friction of spinning and electronic limited slip differentials are controlled by the car's computer it reads wheel slip and then commands clutches electronically to tighten or ease up their engagement on one wheel or the other and within those four major methods of doing limited slip there's also another layer some that will sense torque and others will sense wheel speed to make their decision about what to alter so now you know when you get a car that has a limited slip differential it's got some kind of technology built into this power split device that allows it to sense when a wheels lost traction and send more power or torque to the one that hasn't it helps you with performance traction and safety