What would make a rear axle sound like popcorn?

[Beakster]

Hi,

 

So my front wheels where locked up (caliper problem now sorted) and I tried reversing until I span one of the rear wheels. After that as I drove I have a sound like pop corn popping in the microwave. It gets faster with speed and is most noticeable at low speeds. It's coming from the back axle area.

 

The car still drives fine. I lifted the back end off the ground and the wheels rotate fine and seem free of problems. I put it in gear with wheels off ground and they spin fine without making the noise.

 

It seems to only be when the car is driven that it makes the noise. Any ideas?

[baz105e]

prop universal joint ?

[Pipster007]

Have you checked for a stone in the tyre tread first