From what I can gather so far - the springs pre-load against the spider gears attached to the shaft, and that metal on metal contact is what creates the "friction" to "lock" the axles for a lsd-esque differential action.

But that metal on metal contact sure seems like a good way to get plenty of metal shavings in the diff <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

So aside from the materials it is made from, that device sure looks like something that could be made in a garage with some decent tools... May just have to try that with a spare diff <img border="0" title="" alt="[Smile]" src="images/icons/smile.gif" />