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  • 4+3 Transmission Gear Switches
  • 4+3 Transmission Gear Switches
  • 4+3 Transmission Gear Switches
  • 4+3 Transmission Gear Switches

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  1. #1
    Member AussieCorvetteNut's Avatar
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    Dec 2010
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    1984 Two-tone Blue Coupe
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    Default 4+3 Transmission Gear Switches

    Hi Guys,

    I am like many out there that are having trouble sourcing ball switches for the side of the Doug Nash 4+3 Transmission System.

    I can locate GM 14057528, the Overdrive Override switch 3rd - 4th (which is also the back up switch), but I cannot locate GM 14057529 the Overdrive Override switch 1st - 2nd...GM in their wisdom decided to discontinue the part...very smart fellas!

    The difference from what I can make out, is that one switch is naturally open circuit switch and the other is naturally closed.

    I am pulling the DNE 4+3 out of the 84 on the 26th December to rebuild both the 4 speed and the overdrive unit, as I have rebuild kits for both...thanks Ecklers.
    While I am there, I would like to replace these ball switches, but they are rare.
    Can anyone help with where I could look to buy these units?
    Rock Auto has GM 14057528 for a few dollars, but not GM 14057529.

    The plan then is to bypass the computer for the operation of the OD, as my console switch is operational, I can use it to manually engage the OD.

    From what I have researched on the internet, you can bypass the ECM and take all the smarts out of the system. If you pull terminal A7 on the 24 pin cluster and pull terminal C7 on the 32 pin cluster and then join these two, it bypasses the ECM. You basically end up with over-drive in all 4 gears...an 8 speed 84 Corvette.

    Do any of you have any thoughts on this?

    Appreciate your help.

    Tony

  2. #2
    Member xfirez51's Avatar
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    1992 Black Rose ZR-1
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    Default

    I owned my 84 4+3 for 24 years and I never drove it in OD until I was out cruising and in 4th.
    2nd and 3rd OD were sort of useless IMO.

  3. #3
    Member AussieCorvetteNut's Avatar
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    Default Thats my plan...

    Quote Originally Posted by xfirez51 View Post
    I owned my 84 4+3 for 24 years and I never drove it in OD until I was out cruising and in 4th.
    2nd and 3rd OD were sort of useless IMO.
    I agree, OD in anything less than 4th isn't needed, GM could have solved the problem with offering a 5 speed transmission.

    My plan is to get the OD working, by bypassing the ECM and taking all the smarts out of the system. Once it is working manually, I will be able to cruise on the highway at 110 km/h without it doing 3000 rpm.

    The previous owner (I have only had her a few months) had the philosophy to fix it as it broke...I like the preventative maintenance approach.
    He didn't need the OD working to cruise around town.

    The gearbox and OD are leaking, and by looking at the service history, he hasn't addressed these issues, just kept topping up the fluids...gear oil and trans fluid.

    I think it is time the gearbox and OD came out for overhaul.

    My concern is that he did the clutch last year and I am having issues with the throw out bearing and what I think maybe a worn pilot bearing, and by having a leaking transmission, the gear oil won't be doing the clutch any good.


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