Re: Overdrive
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Forum Ambassador
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You need to determine if it is electrical or mechanical that is causing the drop out but the symptoms sound more like something electrical is letting the solenoid disengage.
For electrical, assuming it was installed properly in the 39 conversion like a stock install would have been with Packard components in the 48-50 cars where it probably came from, there are 3 sets of contacts in series as well as wire connections and the relay that if any should open will cause the unit to disengage. Here is the order in which I would check. A known problem item is the lockout switch at the end of the underdash bracket. The switch plunger is plastic and can wear a groove in the end as it slides against the lockout knob rod. The groove lessens the plunger travel so the switch doesn't engage securely. Vibration can cause it to open and drop out of OD. If the button happens to rotate a small amount as the knob is pushed in again the switch will make partial contact until vibration opens it again. The governor or the wire connecting it to the kickdown switch is a possibility -- particularly the ground connection to the small metal strap on the governor bottom. The screw completing the circuit has been known to loosen and make for a poor connection. Any inline connectors in the wire need to be checked too. If those are good the only thing left in that part would be the governor contacts. The kickdown switch could be acting up or became misadjusted so it is opening before it should. It could be the switch is dirty or just barely making the connection and if it loosened and moved in the mount the accelerator could be hitting the plunger before full throttle. The relay and its fuseholder and contacts are another known source of intermittent problems. The last and extremely remote electrical item would be the solenoid. It is possible but not likely that heat is causing the hold coil to open and disengage. If that were happening you should be hearing a rapid clunk sound as the pull in coil tries to bring the solenoid back in and then releases when it opens its contacts.. Mechanically the R11 is a very robust unit. About the only thing external to check would be if the cable loosened and the lockout lever is not moving very far to the engage side position. That is not very likely though so I would concentrate on electrical.
Posted on: 2017/11/6 16:04
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Howard
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Re: Overdrive
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Home away from home
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When this has happened to me, it's because the OD isn't getting enough juice to power the solenoid. I may have both driving lights and headlights on, radio and the heater on fast, or my battery is down from sitting.
Watch the ammeter. It usually goes in if I speed up, if the generator is doing its job. EDIT: Watch the ammeter when the red light is on. If it's trying to charge all the way on C, the solenoid isn't getting enough amps. Speed up if you can to get more RPMs, and let off the gas pedal. It might go in. Otherwise, follow Howard's suggestions. (Which you should always do)
Posted on: 2017/11/6 19:03
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Re: Overdrive
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Forum Ambassador
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Good point. The OD solenoid needs quite a few amps to engage and if the generator cannot output enough current to keep up with accessories the solenoid could have trouble pulling in. Once pulled in, the hold coil doesn't require nearly as many amps to keep it engaged but if there is a bad connection with high resistance somewhere the solenoid might not have enough current to hold. The fuseholder or oxidized contacts in the relay are good candidates to check in that scenario.
Posted on: 2017/11/6 19:28
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Howard
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Re: Overdrive
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Home away from home
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Most times when I've had a car in with the complaint of no overdrive when hot the problem has been excessive resistance in the relay. The contacts themselves can be dirty, but more often the little brass rivets that hold the relay together and which conduct the current have corroded or even had their heads pop off. Push or drill them out and replace them with little brass screws and nuts.
Also, cars before the 23d series had connectors in the middle of the harness between the relay and the transmission. For long term happiness cut them out and solder the wires together.
Posted on: 2017/11/7 7:12
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