On Sun, 26 May 1996, TeriAnn Wakeman wrote:
> TR4 transmission with OD
>
> I was ringing out my newly built & installed overdrive subaheness today
> and noticed something that I'm not sure is right.
>
> When power is applied to the solenoid it pulls a lever up. When I remove
> the power, the lever does not drop, This is with the engine off and the
> internal pump not pumping.
>
> What is supposed to return the arm to its disengaged position? The
> solenoid only works in one direction and I do not see any springs. Is
> thsi done from pressure from the internal fluid pump?
>
> I just hope there isn't a return spring inside the solenoid that isn't
> working.
Some O/D solenoids do have a light plunger return spring, some don't. In
any case, the spring is too light to handle the whole job of returning the
solenoid lever to its at-rest position.
The solenoid lever is on a cross-shaft that goes to the opposite side of
the overdrive. At the other end of the cross-shaft is another lever (the
valve lever) on which rests the valve plunger. This is an internal lever,
not the external one on the right-hand side of the unit. The external one
is for adjusting purposes only. The valve plunger is spring-loaded by a
fairly strong coil spring..
When the solenoid plunger retracts it lifts the solenoid lever, which
rotates the cross-shaft, which lifts the valve lever, which lifts the
valve plunger, which lets oil pressure lift the valve ball off its seat,
which lets said oil pressure engage the overdrive. Phew! Rube Goldberg
would be proud...
When the solenoid releases, the pressure of the spring on the valve
plunger should rotate the assembly the opposite direction, returning the
solenoid lever to its at-rest position. If it doesn't, then any of the
following could be the cause:
o The solenoid lever is so far out of adjustment that even with the
solenoid plunger fully withdrawn, the valve lever doesn't lift the valve
plunger. This means there is no spring pressure to move the assembly
the opposite direction. Check this first. If you don't know the
adjustment procedure, write again and I'll provide details.
o The solenoid plunger is sticking. Check for dirt and/or corrosion.
o The cross-shaft doesn't rotate freely. Check the solenoid lever and the
adjusting lever on the opposite side to see if either is bent and
hanging up on the O/D case.
o The valve plunger spring is weak, broken, or missing.
o The valve plunger is sticking in its guide.
o The bottom end of the valve plunger is worn flat, causing it to hang up
on the valve lever lever. The bottom end of the plunger should be
rounded. If it's worn flat, replace the plunger. While you're at it,
might as well replace the valve ball too.
o That TR4 tranny knows you plan to put it in a TR3, and is protesting
the only way it can. All of the above are correctable, but not this.
You'll just have to get a TR4 to go along with the tranny...
Have fun!
-----------------------------------------------------------------------
Chip Old 1948 M.G. TC TC6710 NEMGTR #2271
Cub Hill, Maryland 1962 Triumph TR4 CT3154LO (daily driver)
fold@mail.bcpl.lib.md.us
If cars had evolved as fast as computers have, by now they'd cost a
quarter, run for a year on a half-gallon of gas, and explode once a day.
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