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Technical TH350 and leek at speedometer cable hookup

Discussion in 'The Hokey Ass Message Board' started by Hotrodjohn71, Aug 7, 2021.

  1. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 67

    Hotrodjohn71

    Meant to spell it LEAK.
    Hi group, I've got a question about my TH350 speedometer cable leak before I tear into it again.
    I just put in new seals and it still leaks.
    It's not leaking from the speedometer gear housing, but just from the part where the cable plugs into the plastic gear.

    Mine is not the bullet style speedometer drive, it's the pre 1977 housing style.
     
    Last edited: Aug 7, 2021
  2. Driver50x
    Joined: May 5, 2014
    Posts: 151

    Driver50x
    Member

    Did you change the inner seal, as well as the outer one?
     
    SlamIam, Hotrodjohn71 and squirrel like this.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 49,501

    squirrel
    Member

    Also, what type of housing is it? They made a pot metal one in the later 70s that would wear out...the steel type works great, if you put a new seal in it, and also inspect the gear to make sure it's not worn out (they usually develop a groove where the seal lip rides on it)
     
    Country Joe, SlamIam and Hotrodjohn71 like this.
  4. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,761

    Mr48chev
    ALLIANCE MEMBER

    Link for examples as you can get the pieces locally.
    TH350 Speedo Housing Kit w/ Extra Seals & Retainer Bracket Speedometer Turbo 350 (classictransmissionsolutions.com)
    Sometimes on a high mileage transmission the shaft on the driven gear or the aluminum gear housing gets worn to the point where new seals won't totally stop the leak. My stalls were next to the stalls of the transmission mechanic at the Pontiac dealership we worked at in the mid 70's and he showed me one or two that the shaft on the gear was worn quite a bit on that had been leaking. The transmissions he rebuilt or worked on flat didn't leak when he got done.
     

  5. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 67

    Hotrodjohn71

  6. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 67

    Hotrodjohn71

    Thank you guys. Sounds like my setup is worn out.
     
    Driver50x likes this.
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 49,501

    squirrel
    Member

    It helps if you inspect it closely, and see if it's worn out.
     
    Hotrodjohn71 likes this.
  8. SlamIam
    Joined: Oct 8, 2007
    Posts: 449

    SlamIam
    ALLIANCE MEMBER

    Changed mine to the bullet style with new seals and no more leak - now for that shifter shaft seal...
     
    Hotrodjohn71 likes this.
  9. carpok
    Joined: Dec 29, 2009
    Posts: 449

    carpok
    Member
    from Indy

    How’s your transmission fluid level if it’s over full it will leek too.
     
    Hotrodjohn71 likes this.
  10. Country Joe
    Joined: Jan 16, 2018
    Posts: 322

    Country Joe
    Member

    I had a similar problem. I changed seals and still leaked. Then I noticed the gear shaft had a groove worn in it. New on left , worn one on right. I replaced it and it was fine. this was the bigger speedo insert. Not sure if the bullet speedo is relatable at all to the bigger unit.


    speedo.jpg
     
    Hotrodjohn71 likes this.
  11. Hotrodjohn71
    Joined: Feb 25, 2018
    Posts: 67

    Hotrodjohn71

    Thank you fellas, I really appreciate it.
     
    pprather likes this.

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