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Fingertip overdrive control


Robin (UK)

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A while ago I posted a message seeking an electronics wizard to build a relay for my overdrive.

Here's the original thread...

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=26265

Well, I found a guy on the UK who built and supplied the unit for about $50 and I fitted it yesterday.

It's brilliant.

One push on the gearshift button for overdrive, one push to come out of overdrive.

I'll be taking the car on a run on Friday, so I'm looking forward to using it on the motorway.

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What do you do for a shift cable? still use it or stay in od all the time and put up with the free wheeling?

I have a lock-out cable so I can use the standard 3-speed with no free-wheeling.

With the OD cable pushed in the transmission will free-wheel.

The push-button shifter knob provides a single-wire feed to the governor, so with the cable pushed in I have the option of overdrive on/off activated by one touch on the button.

It's a simple set-up but very effective.

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  • 3 years later...

Hey Robin - Did the relay you find work out for you?  Do you have time to create a small wiring diagram?  I bought a 6v VW relay, would be interested to compare to what you had made. thanks mate! 

 

Mark

 

 

I have a lock-out cable so I can use the standard 3-speed with no free-wheeling.
With the OD cable pushed in the transmission will free-wheel.
The push-button shifter knob provides a single-wire feed to the governor, so with the cable pushed in I have the option of overdrive on/off activated by one touch on the button.
It's a simple set-up but very effective.

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Hi Mark, Hi Lloyd,

 

My relay works great but I'm afraid I can't give you any idea of the internal workings of the 'magic box' as it was built by an electronics expert and supplied sealed and ready to go.

 

If you're stuck, I can try to contact the guy who made it to see if he's still making stuff. I believe he was only doing this sort of work on a part-time basis and it's quite a few years since I got mine.

 

Chris is just about to fit his overdrive and managed to talk me into letting him have my spare Shift-Rite knob.

I believe he's going to try to wire it via a 6V VW headlight latching relay.

I'll report back on here when I get news of how that has worked out for him (should be in the next couple of weeks).

 

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I bought my suburban wired this way. A toggle switch enables/disables the overdrive. I have a diagram he gave me I can dig out if people are interested. It took me a while to understand that if I keep the cable mechanism  pushed in I am as someone said above free wheeling - no over drive / switch off will get me up a hill, but will not provide transmission breaking down a hill, unless I pull the cable handle out too.....

Now I just have to get the darn thing running again... Im stumped - other post.... any N. California gurus out there that can lend a hand???? I'll look for the diagram if there is interest.

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Use two bosch relays. shiftrite is the ground circuit for the first relay. It is wired normally closed.  Battery power goes from the normally closed relay to the second relay normally open. When the gov grounds out the second relay closes then the solinoid acts shifting the od in. When the shiftrite button is pushed it opens the battery circuit and the solinoid shifts out of od. As long as you are under power from the engine it should not shift back to od. Just ease up on the throttle and it shifts to od. hope you can make sense out of this. Its clear in my mind.

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Robin,

I am also interested in the set up for the overdrive. I have a two wire push button on the gear shifter but I would like to see about what you have described here with the one wire set up. I would be in the market if your guy will make some more. If you have a diagram of the set up and wiring please send to me PM.

Larry Brauer

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Thanks 52,  I appears on your diagram that there is a two wire switch betweent the ignition and the the 86 terminal on the relay.  That would have to be a two wire switch.  In the case of the shift rite knob, there is only a one wire coming from it.  So hence my conundrum...  maybe someone that has wired one of these can tell me how the diagram you've supplied is modified to accomodate the single wire knob?

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so in that case would I assume that the switch grounded itself to the gear selector lever?  Pardon my amatuer questions... my knowledge in this arena revolves around the flow of current in one wire and out another.

 

(edit) maybe the term bonded itself would be better than grounded itself).

Edited by Mark D
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Trying to turn this into something my non-electrical mind can understand.  I took a copy of the traditional OD wiring diagram and modified it to show what I think is correct.  Question for you all, what gets hooked to terminal 6 on the solenoid, seems to me there is a ground missing.  Also as noted prior, not sure how the knob gets grounded? 

 

post-3941-0-03344700-1427824113_thumb.png

 

Here is the original image.

 

post-3941-0-06724500-1427824339_thumb.jpg

Edited by Mark D
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Hi Guys,

The shift-rite operates like the horn button...

 

The single wire is a live feed.

The contact is normally open.

When the button is pressed, the circuit closes to ground and allows current to flow.

When it's released the circuit will open again.

 

To engage overdrive (and keep it engaged) the overdrive needs a constant supply, so...

 

The momentary contact of the shift-right needs to be used to trigger a latching relay.

The other side of that relay will then open and stay open, or close and stay closed, to supply the overdrive.

 

I hope this makes sense.

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Yes, they are not showing the grounded part of the circuits.  (Note that the positive post of the battery is not shown with its grounding cable.)  It is assumed that each component is grounded.  Likewise, your shift-free knob would be grounded through the shift lever, shaft, steering column, and frame.

 

The car companies have saved a zillion feet of wire by grounding the one side of the circuits.       

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