Hey, all,

I've got a worrisome but phantom problem with my 1991 Civic.  When I'm
backing up from a parking space, in other words, after turning the car
on and putting it into reverse first thing, I'll get a little ways out
of the space and hear a loud bang like I hit something and the car
stops and won't back up anymore.  It sounds and feels just like I hit
a large object, but there's nothing there.  The noise seems to come
from the back of the car.

The first time was several months ago at Christmas.  I could get it to
produce a smaller noise the next few times then, but after the first
time, it backed up and kept running.  Nothing going forward that I
noticed.  I got a mechanic to come out to the house and he put the car
up on ramps and checked the front and back suspension thoroughly and
also ran it backwards and forwards and couldn't find anything.   He
couldn't even get it to make the noise.  The car ran without problems
since then,  sevearl 100+ mile trips on interstates, several thousand
miles of shorter trips.

Today without warning, it happened again.  Backing up out of a parking
space, wheels cocked in the opposite direction of what they were the
first time this happened, and a very loud bang and the car stopped.
Pulled it into a parking space, tried to back it up a little, and it
stopped after a few feet.  It felt exactly like it trying to roll over
a large log.  Tried to pull forward and this time it didn't even want
to do that.  Turned it off. let it sit for a few minutes and turned it
back on again.  At least  I could get it forward into the space.
Suspension looks absolutely normal, tires looks straight.

Anyone know what would cause this?  I

Chris