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'66 chevy 3-speed 'overdrive'???

Discussion in 'The Hokey Ass Message Board' started by clemdaddy, Mar 10, 2008.

  1. clemdaddy
    Joined: Jan 10, 2007
    Posts: 147


    i bought a 66 chevy 1/2 ton truck with the 3 speed overdrive trans and i can't figure out how it works. the motor was out of the truck so i couldn't test it. and there is no cable pull on the dash like i would have thought.

    my questions are what engages the overdrive unit. vacuum or some electric solenoid? and how does it switch on from inside the cab. and third, is it worth keeping.

    the only info i found is it is a saginaw fully syncronized unit and the overdrive seems to be part of the trans not a seperate unit behind the trans.

    thanks for any thing you can add.
  2. Model A Vette
    Joined: Mar 8, 2002
    Posts: 1,072

    Model A Vette

    If it really a 3spd Sag with overdrive it will have a solenoid sticking out on the driver's side just behind the main body of the trans. The solenoid is what does the OD shifting. The cable under the dash was to lock out the OD.
    The OD is in the tail housing.

  3. overspray
    Joined: Jan 14, 2003
    Posts: 1,267


    Read and ye shall be enlightened (or confused more).

    Good score on the 66-up saginaw. This is the one you can put the OD unit behind the Saginaw 4 speed trans.

    Here's the info on putting the OD on the 4 speed. Look for the PDF files in the upper left corner and click on them. It should be 1966 and up not 1965 transmissions, just the fully syncronized 3 speed W/OD.
  4. clemdaddy
    Joined: Jan 10, 2007
    Posts: 147


    thank you 'overspray' you my friend are a wealth of information.
    i never even thought about using with a 4-speed and i was wondering what to do with that old saginaw 4-speed i've had for years. overdrive it...

    thank you too 'model a vette'
    youz guys are the best...

  5. 65carryall
    Joined: Apr 19, 2008
    Posts: 1

    from Nebraska

    EDIT- just realized that one of the links above was the operations manual. I am reading it now, but would still be interested in any further comments. Thanks!

    I just stuck what I believe to be a 3 speed overdrive in my 65 chevy carryall. I do not have any of the wiring or cable completed and just had the driveshaft fitted. However, when I was going to pull it out of the shop with the driveshaft in place it would not budge and I thought I had read something about not being able to freewheel in reverse without having the overdrive set right. Does not being able to freewheel backwards mean that the overdrive is engaged or disengaged? Is there a quick way before I get all the wiring done to simply keep it locked in a single mode or at least a mode that allows it to freewheel one direction or the other and for me to be able to drive it without damaging anything? I know really nothing about the transmission and would appreciate any operation do's or dont's or information in general. THANK YOU!

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