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700R4 speedometer output question

Discussion in 'The Hokey Ass Message Board' started by baker53, Dec 11, 2010.

  1. baker53
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    baker53 Member

    I have a 700R4 transmission with a pulse generator output for the speedometer and would like to convert it to a mechanical output to drive the mechanical speedometer in a 53 Ford. Any guru's out there know if the the electrical components on the 700R4's output shaft can be changed over to a plastic drive gear and what output shaft housing might be available to house a plastic drive gear gear assembly. Thanks, Bill, Spring, TX
  2. Mr4Speed
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    Mr4Speed Member

    When you take the extension housing of you will need a puller to remove the reluctor wheel of the output shaft and slide a plastic gear on that is held in place with a clip.
    There are two holes for the clip in the output shaft one is for Corvette's only.
    A new extension housing isn't needed.

    To calculate wich gears you need you need to know your axle ratio and tire size
    Only when you know wich gears you need you can buy a gear housing because one fits the 34-39 gears and the other 40 to 43 teeth gears. <!-- / message -->
  3. Tripple G
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    New Philadelphia, OH

    Tripple G Member

    I would suggest you contact the guys @Gearstar in Akron, Ohio. If anyone can answer transmission questions, they can. Sorry I don't have their phone number handy, but they advertise in Rod & Custom, Street Roder, Hot Rod, GoodGuys Gazzette, etc. Bought my 700R4 from Patrick, very helpful. Good Luck!
  4. dbradley
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    dbradley Member

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  5. scottybaccus
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    scottybaccus Member

    It's pretty straight forward. You need the speedo drive plug to accept the driven gear and cable from an early to mid '80s 700R4 vehicle. Then you can pull or cut off the reluctor wheel. There should be a hole in the output shaft for the drive gear retainer clip. If not, drill one. You may find the right location on Google or ask a transmission shop to let you measure one. Push the gear on with the clip and make sure it fits pretty tight. Some shafts not meant to have a drive gear will be a little loose. You can sleeve the gear with a strip cut from an aluminum can or sacrifice a feeler gauge.

    Or.... just read dbradley's link....
  6. 325w
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    325w
    ALLIANCE MEMBER

    We buy the parts at the local chevy dealer. had to borrow the puller from a trans shop.
  7. baker53
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    baker53 Member

    Thanks so much for the great info and assistance. I am looking forward to getting the 700R installed and having the overdrive capability. One other question relating the lock-up converter. How do you handle this? I presume a manual switch, but your thoughts would be most appreciated. Thanks again. Bill, Spring, TX
  8. Weasel
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    Weasel Member

  9. baker53
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    baker53 Member

    Thanks Weasel, I will check that option out. Bill, Spring, TX
  10. potshot
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    potshot Member

    Hi,

    I think you may discover that when you pull the tone ring off your output shaft, that you won't have the small hole needed for the plastic speedo gear retaining clip. To drill the hole, I suspect you'll need a carbide bit.
  11. Mr4Speed
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    Mr4Speed Member

  12. Mr4Speed
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    Mr4Speed Member

    I think this only apply's to 4l60E output shafts. I have never seen a th700(4l60) output shaft that isn't drilled!
  13. baker53
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    baker53 Member

    Thanks potshot & Mr4Speed, I pulled the reluctor gear off the output shaft and the shaft has two holes drilled in it. I am going to transmission shop in the morning and see if I can pick up the clip for the drive gear and the driven gear housing. I have a 400TH driven gear housing, but it has an O.D. that is smaller than the 700R. Do you know if the various 400TH drive and driven gears will work in the 700R? I have quite an assortment of those gears.
  14. Mr4Speed
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    Mr4Speed Member

    The gears of a th400 are not the same.
    If you have one you could use the gears and housing from a th350 with a BOP case (Buick, Olds, Pontiac). if of course the ratio is correct.
    For a Corvette transmission (extension housing) you put the clip in the rearward hole and all others use the forward hole.<!-- / message --><!-- / message -->
  15. drptop70ss
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    drptop70ss Member

    what year trans? I just converted an 87 700r4 to mechanical drive by replacing the speedo output housing with a mechanical gear and removed the VSS housing. Already had the drive gear on the output shaft,it was not a reluctor style setup..I thought all up to 1992 were this way?
  16. baker53
    Joined:
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    Location:
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    baker53 Member

    Mr4Speed: Thanks for the info on the 350Th BOP assy. I guess when I sell my TH400, the buyer will get a tub of drive & driven gears.

    drptop70ss: I'm not sure what year my 700R4 is, but it had the reluctor on the output shaft. Hopefully, the transmission shop will have the parts I need to convert it over to mechanical output.

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