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Th400 vacume??

Discussion in 'The Garage' started by 78Blazer, Jun 5, 2002.

  1. 78Blazer

    78Blazer 1/2 ton status

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    I am swapping a th400 in place of my 350. It appears that all I have to do for the kickdown is hook the vacume to the intake like it is for the 350 and it is good to go??? Or am I missing something here?
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    No, the 400 kickdown is electronically operated on the driver side.

    The 350 is cable operated on the passenger side.

    The vacuum thing you are probably thinking about is the round, goldish color thing on the passenger side down by the pan. That thing is the vacuum modulator. Nothing to do with the kickdown. /forums/images/icons/wink.gif
     
  3. 78Blazer

    78Blazer 1/2 ton status

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    I guess I knew it was cable on the 350 but for some dumb reason I was thinking alls I needed to do for the 400 was hook vaccume to it.

    Ok now if that is the case what do I need to have to make the kickdown work?

    Thanks
     
  4. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Get a Summit Racing catalog, or even a Jegs catalog, too, and look in the tranny section of the catalog and search for a small kit made by B&M, the big tranny company, and they will have a kit to convert to the 400 kickdown. The kit will cost around $45-ish. /forums/images/icons/wink.gif
     
  5. 78Blazer

    78Blazer 1/2 ton status

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    Hey Wes

    Thanks for the help man I found the part. It is like $44.00 Ill have to order it.

    Thanks Again
     
  6. BILLY RAY

    BILLY RAY 1/2 ton status

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    I was told if you put a shift kit in the TH400 you did not need to install the kick down switch. Do you think this is true? The guy that said to do this runs his TH400 that way.
     
  7. thatK30guy

    thatK30guy 1 ton status Premium Member

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    All a shift kit is gonna do is make your tranny shift better and crisper. You should still have a kickdown for when you need the power to actually shift to a lower gear, like when passing a car, etc. /forums/images/icons/wink.gif
     
  8. BILLY RAY

    BILLY RAY 1/2 ton status

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    That is what i thought but guy swears that a good shift kit will force the trans. to down shift from the higher line pressures.
    I will put the switch on but i just wanted to see what you think.
     
  9. HarryH3

    HarryH3 1 ton status Author

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    I got the switch (mounts to the bracket that holds the gas pedal) and the wiring from an old full-size Jeep Wagoneer for $5 at a junk yard. Back in the 70's they had Turbo 400's. /forums/images/icons/cool.gif
     
  10. YtseJam

    YtseJam 1/2 ton status

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    If you won't a forced down shift on drivers demand hook the switch up to the Kick down solenoid. Get one at the junkyard. As far as the modulator goes, get an adjustable one so you can fine tune it. This will allow you to adjust when the trans upshifts. Example you can make it shift later with the turn of a screw.
     

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