Is it normal for the hubs to be locked all the time? I just pulled the front tires on our recently acquired (used) 2007 Expedition 4WD to check the brakes and found when spinning the wheels when on the jack the shafts are turning and the hubs engaged. They look like they are vacuum hubs to me like my old F150 was. Wanted to check before I took it in and find out it might be normal.