Wheel spin in neutral

[No_Skillz]

I had the driver's side of the car jacked up with the wheel off (changing belts) and when I started the car, the hub assembly would spin when I had the car in neutral. It would start out very slowly and speed up. I could stop it by hand. Can someone tell me wtf is going on? WTF

 

[Gs Dewd]

Theres nothing wrong it will do that when the wheels are off the ground.

 

[No_Skillz]

Ok, let's assume this is normal. Can anyone explain to me the mechanics of this? I don't understand how this can happen in neutral on an MT car. This didn't happen when I was installing my suspension (the last time I had the front jacked up and had the engine running).

 

[pneumo]

It's called viscous drag. The gears are covered in tranny oil, when a shaft is spinning fast enough the oil starts to pull on the adjacent gear, spinning it too. It's the same principle behind a torque converter in an automatic trans.