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Another Overdrive question

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When I aggressively step on the gas to speed up, it comes out of OD and will stay out as long as I keeping giving it more gas, speeding up. Once I let up on the gas, it will return into OD.

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Roger, this is not right.

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If I want out of OD entirely, I simply flick the toggle up and it comes out.

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In 3rd and 4th, it should only come out of OD if you have enough throttle (at least 20 to 30% depressed) to get the engine revs up. If you click out of OD in an engine brake situation (throttle off) you can shock the gearbox. There is an OD switch (and relay) on the firewall which needs to be operational and adjusted correctly OR you need to learn when to get out of OD so you won't strain the gearbox.

Cheers,
John
 
That is true John. However, that; "If the switch is functioning correctly" can be a stiff letter in a poor mans pocket book. Consequently, backing up with the OVD engaged is to be discouraged in the interests of OVD longevity.---Keoke
 
If it only drops out once the gearbox/OD oil is up to temperature, then I would suspect you have insufficient oil pressure in the OD to keep the OD clutch engaged. I had the same problem, and it turned out to be that the viscosity of the gearbox/OD oil was too low. I changed out to 90 weight geaer oil and now it stays in no matter what temperature.

On the other hand if it does it at all temperatures, try some of the other suggestions.


Mike Brooks
 
You might try changing to Redline MT90 oil and slightly adjusting the engagement lever arm.
 
Just to add my $2 (adjusted for inflation)... My OD does not jump out on acceleration and neither did the 1966 BJ8 I had in 1966 that was new off the showroom floor. I don't think this is normal opperaion.
 
[ QUOTE ]
Consequently, backing up with the OVD engaged is to be discouraged in the interests of OVD longevity.---Keoke

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Hi Keoke, I agree that it's better in principle to manually switch off the OD before going into reverse but it's one of those things that is easy to forget. That's why it's important to check that the gearbox switch is working properly.

Cheers,
John
 
Well Yeah John, that's a valid point. However, you may not have had the privilege of having the gear box switch stick on while underway. This ususually is caused by the switch actuator ,Anvil, crushing the body of the switch so that the little ball gets trapped in the on position of the switch. You get no warning here. So I still say an once of prevention is worth a pound of cure. Develop a good habit and turn the switch off.---Keoke
 
Hi Guys, just been lurking about as usual. But on this O/D thing, I was leaning towards low oil level in the trans and possible dirty filter, because that can be such a neglected thing. But in looking at the control circuit for the o/d, I just wonder if he could have a failing dash toggle switch. if you close the throttle switch quickly, that in its interlocking principle would keep the relay coil energized via the c2 contact. so just letting off the gas pedal should absolutely not have an effect on the o/d staying in. But if power was lost from the toggle switch, when you again go to accelerate thereby openning the throttle switch you would be losing the interlocking effect of the closed throttle switch and deenergizing the relay coil and openning the relay contacts thereby dropping out the o/d.
 
Hi Vette, I had a bit of time following that. /ubbthreads/images/graemlins/grin.gif-However, if the dash switch fails to close failing to energise the OVD relay then no power can be transmitted to the OVD Solenoid.---Fwiw---Keoke
 
Today I tried the proceedure that John Loftus suggested. I turned the ignition sw on without starting the car, engaged the OD sw and proceeded to move the gear shift lever side to side in neutral. When moving it to the right, I was able to hear the solenoid activate. I pressed the accelerator down while moving the shift lever. I could press the accelerator all the way to the floor and the OD solenoid continued to activate when I moved the gear shift to the right. Could this mean the throttle cut off switch is faulty?
Charlie
 
Charlie,

Good to hear the gear switch is working but for the thottle switch testing I forgot one step near the end /ubbthreads/images/graemlins/blush.gif. Turn the OD switch OFF and then move the gear lever left and right. You should still hear the solenoid click. Then slowly apply accelerator until the clicking stops. The thottle switch only comes into play when the OD sw is off (allowing the OD to switch off only when a certain amount of throttle is applied). Make note of how far you need to push the accelerator pedal before the solenoid stops activating. The workshop manual says it should be around 1/5 of the total travel and this can be adjusted by loosening the arm on the throttle switch and rotating the switch shaft with a screw driver.

edit: additional thought. I fine tune the adjustment of the throttle switch so it cuts off during normal acceleration through 2nd gear. Let's say you have switched the OD sw off and come to a stop. When you accelerate normally through 1st and/or 2nd gear and then go into 3rd if the throttle switch is adjusted for too much pedal movement you could go straight into 3rd OD. This will bog down your motor and make you look like you missed a shift /ubbthreads/images/graemlins/blush.gif Of course you don't want to adjust the throttle switch for too little travel either because you override the down shift gearbox safety aspect of the design. Hope this is clear .. the OD operation can be a bit confusing.

Cheers,
John
 
One thought crossed my mine when testing as John suggested. If you have a Petronix electronic ignition rather than points, it is possible to burn up the unit if the ignition switch is left in the "on" position for any length of time without the engine running. I believe disconecting the coil would prevent any damage to the Petronix.
 
Skip,

Good point! (pun acknowledged;) I think Petronix recommends no more than 30 seconds of ignition with the engine off. I've also done this "test" when idling. It's still easy to hear the solenoid actuate once you know what to listen for.

Cheers,
John
 
Hi Shorn, good suggestion might even disconnect the coil feed to keep from over heating the coil when the point's may be closed.---Keoke
 
CoastalMan, Is the throttle cut off switch faulty? Run the switch off test first that John noted and see what happens. If you pass that test the Throttle switch is good.---Keoke
 
Gentlemen, all the test are certainly valid, I just want to clairify my point. That is that if the relay has become energized because we have turned on the toggle switch, but yet the toggle switch could be intermittenly failing, The relay coil would stay energized thru the the c2 contact until the throttle switch is openned again because the c2 contact gets its power from the A3 power source which bypasses the toggle switch. So if the toggle switch has allowed it's circuit to open in error, the relay stays energized until the throttle is opened. This is the scenario that John was referring to when he discribes willfully turning off the toggle sw when coming to a stop, yet the o/d does not come out of o/d until you press on the gas and open the throttle switch. You realize that this is to ensure that the o/d never shifts while the engine is decelerating. When you touch the gas pedal after turning the dash toggle switch off, then it drops out of overdrive. Because now the engine is accelerating at least alittle. If the toggle switch is not staying in when you want it to, and you go to hard accleration, the o/d would drop out. /ubbthreads/images/graemlins/wink.gif
 
Hi Vette,
But the throttle switch actuates at about 1/5 pedal travel .. about 1" of movement. These guys are talking about a drop out that only occurs at full thottle and OD function that returns when backed off. That doesn't sound like an intermitent short to me unless it's caused by something consistent like vibration (high rpm's?) Anyway, when my OD switch on the dash failed (dirty contacts) the OD would not work at all. I think some of the other ideas (including yours) of low oil level/dirty filter/mis-adjustment are more plausible but seems like the jury is still out. /ubbthreads/images/graemlins/grin.gif For now it's a bit of a mystery.

Cheers,
John
 
/ubbthreads/images/graemlins/iagree.gif John. While the lucas switches get a lot of bad publicity their main failure mode is intermittent contact when activated due to dirt and corrosion on the contacts. When positively in the on or off position I have never experienced intermittent operation. Even so ! if it would intermittantly turn off when on, there is no reason to suspect that it would not also turn on when off.---Fwiw--Keoke ?
 
I plan on running John's test tomorrow and will let you know how it goes. Very interesting information! Thanks to all.
Charlie
 
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Even so ! if it would intermittantly turn off when on, there is no reason to suspect that it would not also turn on when off.---Fwiw--Keoke ?

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Not likely. ?????

The only thing required for the contact to be off when it is supposed to be on would be a slightly dirty contact or poor connection.

OTOH - For the contact to be on when it is supposed to be off, would require an insulation failure or a broken part. Not impossible, but not as probable.
D /ubbthreads/images/graemlins/wink.gif
 
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