Why is it bad to use 4H or 4L on pavement?
In: 45
When you turn, the wheels on the outside of the turn have to travel a little further than the ones on the inside of the turn, because a large circle has a bigger circumference. This requires the outside wheels to turn faster than the inside wheels.
A car’s wheels are able to rotate at different speeds thanks to a special device called a differential (get it, “different”). When the wheels rotate at different speeds it’s referred to as “slip” and depending on the car you might have a limited slip differential, open slip, or locked (locker) differential. Its kind of hard to explain, it’s a lot easier to see demonstrated in the following old video.
[https://www.youtube.com/watch?v=yYAw79386WI](https://www.youtube.com/watch?v=yYAw79386WI)
When you use a locked differential, or 4H/4L, then the wheels can’t rotate independently anymore. 4H/4L lock the front and back axles together, while a locked differential locks the wheels on the same axle together. So now when you turn or go around a curve on dry pavement, the wheels want to rotate at different speeds but the can’t, and you end up with one of the wheels getting dragged along and also putting a lot of strain on the differential as it tries to stop it from spinning fast enough.
On slick pavement, sand, mud, snow, etc it doesn’t really matter because the tires can slip against the loose surface. But obviously getting power to all of the wheels is sometimes very helpful offroad especially when one wheel is stuck in the mud or something and the open or limited slip differential would not transfer power to where it’s needed.
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