Slipstream - October 2007

From the Tech Q & A - 911 (1974-1983)
by Harry Hall, Mid-911 Tech Advisor
Question: Haven’t seen question like this before.
Parked my car in reverse. Shifted into neutral and
started car, clutch in. Released clutch in neutral and
car moved in reverse!
Found that shifter would seemingly engage all forward
gears, but would not move forward while a gear was selected
(seemed like both a forward and reverse gear were
engaged and car would strain when clutch was released).
Could select all forward gears but shifter would not go
into 5th / R gate. Checked shift coupler. Found in as new
condition. Played with it some, reassembled. Shifted around
all gears (could now move shifter into 5th/R gate). Now
transaxle is in a forward gear and will move forward when
clutch is released and shifter is again in neutral position.
When any gear is selected, car again strains. Is this
something that can be possibility corrected from the access
plate to shift fork on bottom of transmission?
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Answer: As you have surmisede, the transmission is in
reverse independent of the shifter. If you put it into
a forward gear and let out the clutch with enough
gas on, you will break something in the trans because it can’t
move in two different gears at once. Reverse is the easiest
gear for this to happen in since it has no synchro mechanism
to resist popping into gear.
What happened is that you generated enough momentum
to put it in reverse without having the shifter firmly in the slot
in the 5th/reverse shift fork shaft. The shifter moved back to
neutral but left the trans in reverse. You can correct this, but
not through the access plate.
Put the shifter in neutral in the 1st/2nd position to get it
out of the way. Then raise the front of the car higher than the
rear if you don’t want to drain a lot of the gear oil out. Remove
the backup light switch (It’s not easy, but I’ve done it a
number of times.) and find something you can use in place of
the switch pin or to push on the switch pin so as to push the
shift rod back into the neutral position.
If it happens again, you will need to remove the access
plate on the bottom of the trans, loosen the two nuts that hold
the pivot fork for the shifter, and reposition it slightly in the
direction that makes it more difficult to generate force in the
2nd/4th/reverse direction from the neutral gates.
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