1984 087 auto-trans almost locks in reverse

[Helge Wunderlich]

The automatic transmission (087 three-speed) in my 1984 100 (WC
engine, 185000 km/116000 miles) has developed a strange problem: When
backing, it feels as if the brakes are dragging, except the resistance
is jerky. The problem is noticeably worse when hot. Also, the "park"
position does not work anymore. Should I start looking for a new
transmission, or is there hope ?

If I have to replace, would it be possible to install a four-speed
transmission ?

Here's the long version:

One evening, I stuck it in first, and ran it a bit hard for a few
minutes, alternating between full power accel and hard braking. It
went on for no more than five minutes.

When I got home, I noticed that the "park" would not "take". This has
happened a couple of times before, so I just pulled the hand brake and
went to bed.

The next morning, I noticed the resistance when backing out. Knowing
that the rear brakes were in horrible shape (pictures available if
anyone is interested), I assumed the hand brake was sticking, and
ordered some new rear brakes. Had thought about that for some time
anyway, so I didn't check any further.

After installing the new rear brakes (calipers, discs and pads), the
hand brake works like it never has, and the stopping power has
improved considerably (actually takes a little getting used to), but
the transmission problem persists.

Here are the tests I have done:

- When I put the selector in "R", the transmission starts pulling
right away, but after a small jerk backwards, the car stops. Adding
throttle makes the car move backwards, but with considerable
resistance. The resistance is not smooth, like with stuck brakes, but
with noticeable jerkiness.

- When the selector is in "N", the car rolls both forwards and
backwards smoothly and frictionless.

- When the selector is in "P", the car rolls just as well. Could this
be related ?

- On flat ground with the selector in "R", the car rocks easily back
and forth within the slack in the driveshafts (all wheels move
freely).

- Backing uphill makes the problem much worse than on flat ground,
probably because it takes even more throttle to move it.

- With the front jacked up, the front wheels move smoothly both ways.
With one wheel blocked, the other one moves smoothly, although a
little more resistance when rotating backwards than forwards. The
resistance is smooth and feels "hydraulic".