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should i just automatically lock the center dif when i'm offroad, or is there any benefit to leaving it unlocked on the trails?


From my experience there is a benefit to keeping it locked on washboard type surfaces..

The washboard patterns tend to make the rear axle bounce up and down hard, and the more power you put on it, it can get right down right violent.

I find that with it in 4x4 and locked center diff with the front wheels helping with the pulling load, the axles don't tend to bounce nearly as bad when pulling under load on washboard surfaces.

Of course airing down helps greatly too.