[TR] TR3 Overdrive problem

Randall tr3driver at ca.rr.com
Fri May 30 09:30:39 MDT 2008


> Sometimes it 
> "sticks" and prevents shifting into reverse, while all the 
> forward gears will work.

Just for clarity, Corey, having the OD stuck on won't prevent shifting into
reverse.  It just won't let the car move in reverse.  (And as everyone
knows, forcing it to move under those conditions will destroy the OD.)

First thing I would check is electrical, just because it's easier to get to.
When the problem happens, try pulling the solenoid wire off the relay (under
the dash, forward of the heater, on the back of the battery box).  If you're
not sure which is which, just pull off both the wires that run into the
tunnel (but try to remember which one goes to which terminal so you can
reconnect them later).  If that releases the OD, then the problem is
electrical, possibly a short at the relay.

Since that's not likely to be the problem, next step is to pull the tunnel
off and remove the stem from the operating valve.  IMO, best to let it cool
overnight first.  Flip the OD on & off a few times (key on, engine off, 4th
gear) to try to release the pressure.  Undo the hex plug on the RH top of
the OD (which may burp out some oil under pressure, but only a little bit)
and collect the copper washer, spring, distance piece and ball under the
plug. (Items 20,18,17,16 in the diagram at http://tinyurl.com/6ye5cu )  Then
use a bent paperclip or similar pushed down the hole in the center to
withdraw the stem (Item 15).  There is a tiny hole in the side of the stem
that drains oil from the center of the stem.  If that hole is blocked, it
can cause the OD to not disengage (or even engage without the solenoid being
activated).  While you're in there, inspect the ball to be sure it's perfect
and that it's seat in the OD casting is in good shape.

Also with the tunnel off, you can verify that the solenoid is releasing and
the operating lever dropping.  If not, there may be grit inside the solenoid
causing it to bind.  You can also double-check the adjustment (tho I doubt
that's the problem).

If all that fails, the problem is likely inside the unit, meaning it has to
come out of the car.

More info at
http://www.buckeyetriumphs.org/technical/AOD/AOD5/AOD5.htm

Randall


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