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Power and No Calculus Required
Eric (Eni) Enescu
Read through a performance car magazine and you will hear mention of the latest electronic LSD, or limited slip differential, in the new Subaru STI (the car, not the disease), or the all-time four-wheel drive in some off-road cars. Cars have differentials, or diffs, and they do one thing: give you power and handling.
Ideally, the driven wheels would get equal torque, but what would happen in a corner? The outside wheel has to travel a greater distance than the inner one, but equal torque would forcibly mean equal speed. Unless you are in a racing car, you don’t want that to happen. A differential splits power to the driven wheels allowing for a speed difference.
In icy conditions, some of you might have noticed that from a standing start, the car doesn’t pull away, but tracks from left to right. This phenomenon is caused by power being uncontrolled (as your car would most probably have an open diff) where there would be a passive control of power to the path of least resistance, ideally the outside wheel. For more control, you can opt for a car with a limited slip diff, or LSD. These diffs allow for a controlled distribution of power to all of the driven wheels. In most cases, LSDs can come in mechanical, electronic or hydraulic form, and the best option mostly comes down to driver preference and what feels best for you.
Differentials make easy driving easier. Without them, carparks would be a pain. Next time you see a technical spreadsheet, it’ll maybe make more sense.
Originally Published in Bandersnatch Vol.49 Issue 07 on December 4th, 2019