Embarking on a Laycock-overdrive odyssey

[David in San Antonio]

I admire your resourcefulness and willingness to build your own parts. Have you explored the cost of buying and shipping parts from the US? Either way, please keep us informed of your progress!

[DkFordor]

David, thanks for your reply.


Regarding an import from the US: The thing is I live in a country where there is both import tax and after that VAT of 25 %. So anything arriving from outside the EU is prone to be somewhat expensive.


Located just next to Sweden - the country of Volvos - getting hold of the parts is rather easy and fairly cheap. Whether or not the adaptation works out - well, we'll see

[DkFordor]

A question for those with a Laycock unit already installed: how is the solenoid wired?

It comes from a 12 volt negative ground, and I don't currently see a way to isolate it from ground. Which would imply that the 12 volt negative ground circuit would have to coexist along 6 volt positive ground - sharing the ground.
My understanding of physics says it probably can work out this way, but reality might disprove it.

Any comments or thoughts on this would be appreciated

Sent from my Amiga 500 with Tapatalk

[GYYSYF]

Originally Posted by DkFordor

A question for those with a Laycock unit already installed: how is the solenoid wired?

It comes from a 12 volt negative ground, and I don't currently see a way to isolate it from ground. Which would imply that the 12 volt negative ground circuit would have to coexist along 6 volt positive ground - sharing the ground.
My understanding of physics says it probably can work out this way, but reality might disprove it.

Any comments or thoughts on this would be appreciated

Sent from my Amiga 500 with Tapatalk

This may help.
Go to youtube and search for Mart's video titled:
Wiring a J type Laycock Overdrive using a Volvo Overdrive Relay. Incl. Pin IDs and Diagram. (2262)

Also you can contact Ford Garage from his web page for original volvo overdrive info.

[Bruce of MN]

I looked through https://www.fordgarage.com/ and didn't find anything on the overdrive.

Any tips on where to find it?

[Herb Concord Ca]

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I had a Volvo O/D in my 29 Special coupe, it ran fine using 6V controlled by a toggle switch. It shifted OK on 6V positive ground.
Today that same O/D and same solenoid is in my Slant Windshield Town Sedan that is converted to 12V negative ground. Again, controlled by a toggle switch.
No need to overthink this!

[Doug Linden]

I concur with Herb, the overdrive works fine off the 6 volt positive ground system. One toggle switch and a single wire. Don't forget the reverse lock out switch you need to add to the transmission tower.

[Tanglfoot]

Yes Ted has my old email address, however David Mossman and I have bean doing Laycock conversions for some years now. In answer to your first question they do operate on 6 volts ok and if you have a cut out switch on the generator this makes the od drop out of overdrive at idle so no safety switch is needed ( you cannot revers in od) You can PM me at
[email protected] Cheers

[daveymc29]

The easiest part to do is wiring the Lay-cock so it won't get the solenoid energized when the transmission is in reverse, which will destroy of badly damage the O/D unit. Looking at a transmission from the rear yoy will observe there are two cylinders running the length of the tower, one on each side, right and left. Viewed this way with the shift lever up, the tube on the right contains part of the shift mechanism that will move the transmission into 1st and reverse gears. The end toward the rear is where I drilled a hole, threaded it, and mounted a switch to break or make contact as the shifting fork is moved in and out of position. The hole drilled was threaded to take a switch that will be interupted when pushed by the shifter being move to the reverse position. I connected the hot wire feeding the overdrive to a fuse, then to this switch, then tested my work to make sure it broke the current any time the gear shift was moved to the reverse position. One could put another switch on the opposite end of the tube to accomplish the same result in first gear, I felt that unnecessary as I am smart enough to not engage the O/D with to power the O/D when the shifter is in first and no real damage would result if it were engaged. From there you can run the wire from that swith to the on/off switch for the O/D when you want to manually make a shift. Mounted my switch where it was covenient to reach with my left hand, you might wish to make it the opposite as you will be shifting the tranny with your left hand.

[DkFordor]

Thanks all - good input and much appreciated!

My intention was/is to use the original OD relay as this gives the switching behavior I think is best and most foolproof. One feature of it is, that once the OD is disengaged it stays disengaged until you actively reengage it. For example if the reverse cut out has been triggered - the OD stays disengaged when the forward gears are again used. I don't think I can achieve this without the relay.

Perhaps I could operate the solenoid on 6 volt, managed by the OD relay via a normal switching relay.

One (stupid?) question - is the solenoid polarity sensitive? I.e. will the pos ground vs neg ground give me problems in that case?

[DkFordor]

Originally Posted by daveymc29

The easiest part to do is wiring the Lay-cock so it won't get the solenoid energized when the transmission is in reverse
...
mounted a switch to break or make contact as the shifting fork is moved in and out of position.

Thanks Davey - this is very useful

Did you consider what happens if the cutout switch fails?
I'm not sure if this should be taken into consideration...

[daveymc29]

One could run a "pilot light" to tell you when the O/D is energized. This would also let you know if the lockout switch fails to operate. I avoided doing that as I felt one advantage to the Lay-Cock layout is that most people will not even know you have an overdrive if you wish to make the controls less visible. No extra lever on the floor, though there will be a push/pull cable and an on/off switch somewhere. I put the cable on the shift lever and it was very convenient there. The shifting switch not so much as it was mounted on a bracket that was on the lest side of my column just below the steering wheel. I also had turn signals and at one time a push button starter switch there. Thought of putting a "pilot light" there also, didn't.

[Herb Concord Ca]

The O/D solenoid is not polarity sensitive, will on either polarity.

[Cartravel]

I just saw this thread while I was researching another issue. I love these overdrives. I have rebuilt several A-types and have one in a Triumph. I have less experience with J-types. I have a J-type in a Model T, but it was built by someone else.


I set mine up using a commodity Bosch relay (cost a few dollars), an operating switch and a switch activated by the reverse pedal. I attached a wiring schematic and some photos. My car is 12v positive ground.


I think if I set one of these up, I would try to use the output shaft from a Volvo transmission and the the drive flange that attaches to the OD. That way you would have the correct splines that could be welded on to the Model A drive shaft.


- Larry Young