Locking Differentials?

[Robert Deis]

Seems to me you guys are giving complex technical answers to a simple
question:

What's the diff lock do?

There is a TON of good information about differnetials and AWD systems out
on the net from folks that have a very complete understanding of it- I'll
summarize in laymans terms, and you can go out there if you need more
detail:

As has been said, the quattro system drives all the wheels, all the time.

This presents a technical problem, becasue when you go around a corner all
4 wheels want to turn at a different speed, so you can't lock them
together or you tear up the tires and transmission.  So, they're joined
with a "differential," which allows them to rotate at different speeds.

However, a simple differential will let one wheel spin like crazy while
the other three are stopped- sort of defeats the purpose, right?  Enter
limited slip differnetials (there are some technical differences between
torsen and limited slip, as I understand it, but the purpose is the
same.)

A limited slip differential limits the difference in speed that's allowed,
so if one wheel is hanging in space and spinning, the other three get some
of the power and help you move anyway.

In extreme cases, when its very very slippery, it may be a good idea to
actually override the differentials and actually lock the wheels
together. In these rare cases, you don't have to worry about tearing
things up because the tires can't grip the road well enough to do
any damage anyway.

So, in these rare cases you turn on the diff locks- and in this much the
sales guy was right- you only do that when its *really* slippery out or
you do damage, and you don't need them the rest of the time anyway. But
you're still driving all 4 wheels.

-- 
------------------------------------------------------------------------------
  Rob Deis                  "Let the people know beforehand what the law
  MiB3347                      is and what they are to expect." 
  rdeis at io.com                              -- 18th Congress, Rec. 75