Overdrives not disengaging

[Bob McElwee]

In St. Louis we have several o/d's that won't disengage when the power to the solenoid is turned off. On my 62 it was fixed by installing a Toyota 5-speed tranny.
However a fellow member has just rebuilt an o/d and when he is bench testing it, it will not disengage when he turns the power off. A judicious use of a hammer will disengage the o/d.
Any suggestions as to the reason/cause of the non-disengagement?
Thanks,

 

[JPSmit]

Mark, Abarth69, and I just spent some time trying to figure out his O/D. You might want to take a look at the throttle switch - under the hood - it is powered by the second relay, and, is designed to prevent the O/D from disengaging under the circumstances of the car rolling fast but the engine turning slow (coasting on no throttle) it is adjustable, and, you should be able to bypass to check.

 

[Keoke]

In St. Louis we have several o/d's that won't disengage when the power to the solenoid is turned off.

It is not the case that the power is being removed from the solenoid when the OD switch is turned off.

Additionally, you must depress the accelerator so that the throttle switch via the OD relay removes power to the solenoid.
-----------------------Keoke--

 

[Bob McElwee]

I didn't describe the problem well enough. On my 62, the o/d would not release even after the ignition was turned off and there was no power. The o/d being bench tested is not even in a car and doesn't have the relays in place. We think it is a mechanical problem but aren't sure exactly what is binding(?) to prevent the release. Neither o/d could be used in reverse when they didn't release.
Thanks

 

[abarth69]

Solenoid switch binding holding it in. Remove the solenoid and follow the manual for adjustments.

Cheers

Mark

 

[Randy Forbes]

Check also, that the (pressure) bleed down hole isn't plugged with debris.

 

[Bob McElwee]

Thanks, I'll pass the info on.

 

[TimK]

If the OD is on the bench, how could the OD engage? Or do you mean the solenoid engages and then won't retract? If this is the case, there is some binding in the linkage to the OD engagement lever (or the solenoid is sticking). Take the side cover off and operate the linkage by hand to see if that is binding.

 

[RAC68]

Bob,

What fluid is in your overdrive?

In line with Randy’s focus on pressure release, a friend who has a similar problem found crud in the release passage. He indicated he cleared the dirt by removing the operating valve plug, spring/plunger, ball, and valve.

Also, if I remember correctly, an overdrive rebuilder ran tests on a number of commonly considered fluids (MTL synthetic, Automatic Trans Fluid, gear oil, 30Wt non-detergent, etc.) and found that the heavier fluids applied so much pressure that they would jam in and not disengage. I appreciate that you are probably not using gear oil but thought it good to mention. I would also check the pressure level when engaged and also determine if the pressure is being released when the OD is shut down.

All the best,
Ray (64BJ8P1)

 

[wheelguy]

Hi Bob.. Allen Hendrix here... We had a rash of this problem around here latley. Turned out to be the oil. If you changed oil recently this may be it. I know of 6 people who used 30wt. non detergent and od started sticking. They all cured their problem by flushing out the oil and changing to Red Line GL-4 75-90. Steve Byers and Ken Fleemming and Larry Currie ,Richard Dryman and 1 guy in MD. Devin Williams. All have stopped their problem with a better oil. John Esposito at Quantum Mechanics is now telling customer to try a oil change first. John is the best at these tranny rebuilds. Seems the 30wt. ND now is sticky and will make the clutches hang up. No problem with the Red Line. Others may chime in if you cured your problem this way. Take care my friend.

 

[Bob McElwee]

Thanks for the updates. I had switched to 40 wt non-detergent so that may have been the problem. I'm not sure what oil Keith was using on the ones he is bench testing. Last update from him was one was now working but the other had too much pressure. I'm out of town and will get with him when I get back and give hime the information.
I really appreciate all the responses.
thanks,

 

[Bob McElwee]

Further info on the bench testing. The o/d are engaged manually initially and if they work that way then they are tested using the solenoid. 30wt non detergent oil is being used. The Red Line will be tried. I think I'll pull my tranny out of the shed and test it with the Red Line, but I'll leave the 5-speed in the car!
Thanks again.

 

[RAC68]

One last side consideration. My experiences with Red Line MTL are both positive and negative. After changing from 30wt Oil, I found my shifting has gotten a just a little smoother but the overdrive engages so smoothly that the only thing I notice is the sound of the RPM reduction. On the negative side, aside from the price, I have found that with MTL, my trans leaks more that previously expected and on the initial fill found the solenoid housing full of oil.

Is my experience unique or common?

All the best,
Ray (64BJ8P1)

 

[John Turney]

I had this happen on mine after rebuilding, and all of the above suggestions were tried to no avail. If I recall correctly, the cone clutch was worn so that it would engage too far and then not release.

 

[Bob McElwee]

Thanks John, all are now working but one. I'll pass the info on to Keith.