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Laycock overdrive type A wiring

Discussion in '"Stock" Alpine' started by dlivi, Jul 11, 2021.

  1. dlivi

    dlivi Donation Time

    Ok , a year ago is spoke with Tom Hayden about my overdrive relay and he sent me a beautiful set up.
    (see pic)
    I have now gotten to the point of working on this OD.
    First I have realized that i have a Series III Laylock type A model 25/3314 OD (see plate picture)
    Second the OD switch on column is a non canceling two wire switch (Series II car)
    Third in addition to the solenoid i see two switches on the OD, 5 wires going to OD unit. two to each switch one to solenoid (see pictures)
    So....Do i need a self canceling column switch or can i wire this to existing non canceling switch?
    Can anyone help with wiring this to the Mr. Hayden relay?

    Attached Files:

  2. RootesRacer

    RootesRacer Platinum Level Sponsor

    Type A ODs were never fitted to series alpines. Cant tell what you have by any of the pictures but I am betting its a D type.
    The thing you really want to photograph is the rear of the trans, this is the overdrive.
  3. Tom H

    Tom H Platinum Level Sponsor

    You can control a Type D OD , (and almost surely a Type A as well) with either a self cancelling switch and relay or with as simple ON/OFF switch. The only issue is that the self cancelling has some convenience and safety features. Both switches make use of the lock out switch on the tranny to prevent engaging in 1,2, or Rev gear. So when downshifting to 2 or 1 with a non-cancelling switch the OD drops out of OD. But you may be surprised when upshifting into 3 that the OD comes back ON as soon as you shift into 3rd, unless you turned it OFF after going to the lower gears.

    You'll need to figure out the 5 wires going to the tranny. The one going to the OD Solenoid is simple. That powers the OD solenoid and comes from OD relay. The other 2 pairs go to the switches on the tranny shift box. One of those switches is for the back up lights and the other is the 1,2,R lock out switch. If you have a SV tranny, with Reverse gear in the Right and back location, then the Lock out switch is on the right side of the shift box. ( I am 99% sure , but maybe someone can confirm this.) The Backup switch is the on the other side. If you have an earlier tranny, with Revers Gear in the up and left position, the switch locations are reversed.

    Once you decide which control arrangement you prefer you can just wire it as I described if you choose and obtain the self -cancelling switch. Do you have a stock OD cable cable harness for a SV ? If you choose to go with the non self canceling switch, the wiring is simpler and easy and does not requite the extra resistor or diode that I sent with the kit. Let me know what harness or wiring you have and I'll describe the wiring steps .

  4. dlivi

    dlivi Donation Time

    Hi Tom,
    Thanks so much for your reply! I am looking into aquiring a self canceling switch as this seems to probably be the best if possible.
    I will keep you posted and will certainly take you up on assistance.

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