Two weeks ago I had my axle and CV joint assemblies replaced on both sides of the car (1996 with Automatic trans). Since then I had been hearing a strange and obnoxious noise, so I decided to investigate this past Sunday morning.

With the car safely supported under the front A-arms and the wheels off (rear wheels were chocked and the e-brake was on hard), I started the car in neutral and then put it into drive to investigate the noise. However, I noticed that while idling in neutral, and without the resistance of brakes (I removed the calipers) the hub assmblies began to rotate by themselves as if the car was in drive. However, the rotating hubs were easily stopped by placing a finger against the lugs. I thought this was interesting. My question is: without any of the clutch bands working the planetary gears, why would the driveshafts spin?

 

gravity, u might have unbalanced wheels

 

because there is no load on the tranny....there probably spinning in different directions as well

 

That doesn't make any sense at all. The driveshafts were freely spinning. The wheels were off the hubs.

Yes, they were spinning in different directions.

Without the clutch bands to hold them in place, the planetary gears freewheel inside the transmission. I suppose that what is happening is that without any resistance on the output shaft, the output shaft joins in on this freewheeling motion. There never really is a complete disconnect between the input and output of the transmission.

There is a very interesting article on how autmatic transmissions work, take a look if you're interested. http://auto.howstuffworks.com/automa...ansmission.htm