Differential Spider Gears

A car’s differential is an integral part in converting the power of the engine to actual car function and movement. In essence, the job of the differential is to take the power that has already been put into moving the gears in the transmission, and use it to help move the car’s actual wheels. The differential is also responsible for tempering that power, as it slows down the rotation of the transmission’s gears. The differential spider gears allow rear wheels to move at different speeds, which is very important in certain driving situations this article will go into further detail about both the differential and spider gears, and how spider gears effect the differential’s (and your car’s) performance.

Many people don’t know that a car’s wheels can, and often do, spin at different speeds. This happens most often on turns, where this ability greatly impacts performance. When you make a turn, each wheel needs to travel a distant distance (the wheels on the side you’re turning towards moves less), so the ability to make wheels turn at different speeds is essential to make a car turn correctly. In the wheels that are not connected to the engine (non-drive wheels), this isn’t a problem, but the wheels that the engine are connected to can’t move separately on their own.

Your driving wheels (i.e. the rear wheels in a rear-wheel drive) are both pushed by the engine and transmission, but the engine pushes out the same amount of power to both wheels. The differential divides the engine’s power, or torque, between the two wheels, and allows the necessary uneven force to be applied to each wheel. The differential is placed between the wheels it affects – between the front wheels for a front-wheel drive, and in the rear for a rear-wheel drive. In all-wheel drive, the system is more complex, and it is actually harder to turn with the four-wheel drive engaged.

Spider gears are the part of the differential that accomplishes this task. The differential, without the spider gears, just transfers the engine’s torque onto the wheels. The spider gears are what split the force between the two wheels. All cars have them, and if they didn’t, they’d literally slide whenever they made a turn. The spider gears work by sensing which tire has the least amount of resistance and applying more torque to that tire. This doesn’t just help with turns, but also when you hit slippery parts of the road. The spider gears can help you get out of that spot. For example, if you get one tire stuck in mud, your car will put more pressure on the tire that is on the road.

If you need to replace spider gears, you’ll most likely need a mechanic. They aren’t very easy to remove or install, and they’ll definitely require more than a basic tool set to replace. You’ll likely need to have a good knowledge of cars and experience working with them in order to do it yourself, especially since you run the chance of damaging the actual differential, which is both more expensive and more serious in terms of damage.

A set of spider gears by themselves should cost around $120 to buy, and the labor costs might be an additional $100, depending on who you go to. Commercial mechanics tend to charge more for this type of procedure. But it you are having a problem with your spider gears, it’s well worth the money, since you run some pretty serious driving risks if they fail completely, not to mention putting a lot of extra pressure on your entire car.



There Is 1 Response So Far. »

  1. Sir/Mam

    I like to know how exactly differential(spider gear) works when one of the Tyre of lets say car(rear wheel drive) got stucked in mud or snow.

    Thanks And Regards,
    Devneet Mahajan
    Mechanical Engineer