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Overdrive reality check question...


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Can anyone confirm or not that when you press your foot down and kick down the BW Overdrive that the solenoid main coil stays "hot" as long as you hold it in direct drive?

 

I just do not remember. I was heading back from out of town and coming up the long grade to the GG Bridge and noticed the AMP gauge was drawing 20 AMPS. As soon as I rounded the top of the hill and the OD engaged it stopped. When you drive down the street and hit 25 MPH there is a momentary blip of the amp meter and that is it. I thought that it did the same thing when you used the kickdown but now I am not sure.

 

Everything is working as it should. I just do not think that the thing was drawing a full load going up a mountain or big hill. My little voice is telling me something is wrong. I just went through the books and it says nothing.

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Anyone out there with a BW OD that is working fine that can take it out for a drive and tell me if yours show the draw while the kickdown is engaged....

 

Thanks, James

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Seems the pull in circuit should be momentary, it should open when the hold in points get closed when that circuit takes over.  It should disconnect the high Amp circuit when the lower amp hold in circuit is engaged.  I have never noticed any big fluctuations on the Amp gauge during OD operation.  I do not have a kick down switch, but that shouldn't effect the internal works within the solenoid.

Edited by greg g
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That is what is odd. For 15 years I noted that when the governor does its thing and the high current circuit comes in and pushed the pawl into the blocker ring that there is a momentary move of the needle of the AMP gauge.

 

I have not paid much attention since I put the rebuilt trans in. It still does the above when it is going to allow a shift into OD.

 

But today coming up the a small hill when I used the kickdown then again a few minutes later when I was climbing Waldo grade to the GG Bridge I noted the amp gauge up at 20 amps or so.  When I crested the hills and the unit re-engaged the amp gauge dropped back to normal.

 

Somehow when the kickdown switch opens the low amp holding circuit of the solenoid and the then grounds the coil which allows the the spring in the solenoid to pull out the pawl the high amp circuit is coming on.

 

What I do not know is why? Will the thing work with the wires crossed on the solenoid ? Is the pawl the wrong one as I think I have a couple or three and they are a little different in length. I know that there were a couple of different length solenoids and I wonder if I played mix and match and created a problem?

 

It would not be good to have that circuit that hot for a long time. I need to figure this out. Anyone have any ideas?

 

James

 

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After sleeping on it, and thinking about it, all night...

 

For reasons not known when the kickdown switch is used the relay is supposed to open and keep both the governor circuit and the high currant circuit which is active as the car is over 25 MPH.

 

I will check the relay and see if the points look like there is a problem.

 

Anyone have any other ideas?

 

James

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As soon as the kick down has been accomplished, the solenoid is ready to reengage the overdrive which happens when the driver releases the throttle, causing the balk ring to move,   In this circumstance, the solenoid is drawing full current...... at a guess 12 amps.  It can make a fair amount of heat but unless one was climbing a steep hill, it would be temporary and no harm is done.   A set of points inside the solenoid returns the holding coil to use when the solenoid

is reengaged..... maybe 3 amps.     The second terminal on the solenoid is the ignition interrupter circuit.    You must be careful not to mix these wires up.

 

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It appears you are reading this correctly.

 

How ever, it appears the kick down switch has a set of normally closed and normally open contacts.  If you had them swapped is it possible it would act as you are seeing?

 

What concerns me though, is that the solenoid pull in winding's should have the ground path broken as they plunger engages.  So then you should not be seeing a current draw that high. 

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I am wondering if there is something wrong with the relay and the points are sticking...or something...

 

This is stumping me. Later today I will take a couple of hours and see if I can run it down.

 

The odd thing is otherwise it is running fine.

 

Keep tossing out ideas folks, the more the better.

 

James

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Well, I took and hour this afternoon and pulled off the relay for the first time in 15 years. I pried the little flanges back and the inside looked as good as new. I ran a relay file through the contacts, but there were fine and then cleaned with elctro-motive cleaner. I let it dry and put some electrical corrosion spray on an the contacts and closed it up.

 

I doubt that was it. That would have been too easy. In the morning, I will jack the car up and check the wiring. I am hoping I just switched the wires on the solenoid. But that would be odd if it can work with them switched.

 

Anyone have any other ideas?

 

James

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Well,

 

Spent the day in the engine bay and under the car. All the wires go exactly were they are supposed to. I spent several hours taking apart the kickdown switch. My spare may be up in Winters as it is not here in San Francisco. I have a spare solenoid, rail lockout switch and relay in the car...but not a kickdown.

 

I pulled the wire at the relay from the "A" side of the kickdown and put a VOM on it and when I wiggled the switch I got a inconsistent reading (sound).  I pulled the switch and took it to the bench and tried it and it felt and sounded, with the VOM attached, a little "flaky".

 

Since I do not have a spare here, I pulled the little metal tabs and took the switch apart. What I found was interesting. The gasket that sits between the bakelite bottom and the shell has shrunk so much that it was crowding the actual switch mechanism. I then cut a new gasket, but my material is a little ticker and it did not make really positive contacts when I pushed in the plunger. I even stretched the two springs a little that push up to the contacts.

 

So I took out the gasket and put the switch back together nice an tight. I then used a little silicon to seal the case to the bakelite  from the outside and wiped off the excess.

 

I checked all the connections and wires. Everything nice and tight. I also took the cap off the solenoid and although I had cleaned it well when I had the trans out and bench tested it, I hit all the contacts with elecro-motive spray cleaner all the same.

 

It is busy here in SF on a sunny Saturday so I could not extensively road test it. I did manage to get it to shift into 2nd overdrive then kick it down hard and race the thing for a block. The AMP gauge read normal. No big draw.

 

So, I still do not know what it was. A sticking relay?  The kickdown was somehow causing a problem?   I do not know.

 

I will take it out on Monday after the commute up to Sausalito and drive it back up Waldo Grade and see what happens on the long hill.

 

Odd. Very odd.  Thanks for the ideas.  James

 

 

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