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Technical Changing the shifting point of 350 T/H ?

Discussion in 'Traditional Hot Rods' started by blazedogs, Aug 2, 2018.

  1. blazedogs
    Joined: Sep 22, 2014
    Posts: 447

    blazedogs
    Member

    I,m not sure I have this right. On my 1940 Ford w. a 350 TH trans there is what is called a ( modulator ) brass in color that the vacuum hose plugs into. If you pull this hose out and look in the opening there appears to be a very small set screw. In my case the trans is shifting way too early. Is this correct ? : turn this set screw (clockwise) to make it shift latter, about 1/4 turn in intervals, each time until you reach the right shift point. ? Gene in Mn
     
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  2. Chavezk21
    Joined: Jan 3, 2013
    Posts: 617

    Chavezk21
    Member

    Yes in to shift later out to shift sooner.
     
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  3. Deuces
    Joined: Nov 3, 2009
    Posts: 18,785

    Deuces
    Member
    from Michigan

    So, how does it run now?????…...
     
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  4. saltflats
    Joined: Aug 14, 2007
    Posts: 10,181

    saltflats
    Member
    from Missouri

    What is the vacuum reading at the modulator?
    You can also change the springs and or weights on the governer to change shift points.
     
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  5. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,173

    6sally6
    Member

    Does a 4L60 (91 S-10) have the same adjustments?
    Please forgive the "butt-in"
    6sally6
     
  6. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,483

    greybeard360
    Member

    Make sure the throttle pressure cable is adjusted correctly.

    B&M, TCI and a few others have kits to calibrate the governor shift point.
     
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  7. If the “kick down” cable, correctly known as the throttle valve cable, is disconnected or misadjusted, it will shift early and very softly. The more the cable is pulled out(the more the throttle is opened) the later and firmer the transmission shifts. This is due to the valve connected to the cable making line pressure higher with more throttle opening. Higher line pressure is needed to hold the clutch packs tighter as more power is put through them. The cable is usually adjusted so that WOT is pulling the cable all the way out.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  8. No. No modulator
     
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  9. Won't do much , as mentioned. Get a governor kit.
     
  10. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,424

    OLDSMAN
    BANNED

    4L60 is an electronic controlled transmission, no vacuum modulator, no kickdown cable. The ECM controls all downshifts and upshifts.
     
  11. Budget36
    Joined: Nov 29, 2014
    Posts: 3,592

    Budget36
    Member

    No...the 4L60E is computer controlled, the 4L60 is just like a 700R4..TV cable.
     
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  12. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,424

    OLDSMAN
    BANNED

    My bad a 91 would be like a 700R4 no modulator shifts controlled by a TV cable
     
  13. XXL__
    Joined: Dec 28, 2009
    Posts: 1,861

    XXL__
    Member

    The OP has a TH350.
     
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  14. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,374

    gimpyshotrods
    ALLIANCE MEMBER

    Yup. No TV cable there.
     
  15. I know it’s a THM 350, but what is the cable that connects to the carb called?


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  16. XXL__
    Joined: Dec 28, 2009
    Posts: 1,861

    XXL__
    Member

    It is usually called a "kick down" as you stated, but it has no pressure metering function like a TV cable you'll find on the later TH2004-R and 700R4. On the TH350, it has a mechanical function, and is not required (unless you want an automatic 3-2 shift at WOT). I've been too lazy to connect it on one of my hoopties for 20 years and counting.
     
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  17. saltflats
    Joined: Aug 14, 2007
    Posts: 10,181

    saltflats
    Member
    from Missouri

    No.
     
  18. 41rodderz
    Joined: Sep 27, 2010
    Posts: 5,022

    41rodderz
    Member
    from Oregon

    Glad that is straightened out .:D I was starting to worry with all the talk of computers and tv cables when the guy stated he had a T350 :p
     
  19. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,483

    greybeard360
    Member

    From the TCI website.... and yes, this is the info on the TV cable for a Turbo 350

    The throttle valve cable (TV cable) is present in all modern cars with automatic transmissions. Many people believe that the TV cable is a detent downshift cable and that this is its only function. In actuality, the TV cable controls line pressures, shift points, part throttle downshifts and detent downshifts. The cable functions similarly to the combination vacuum modulator/cable systems found on other automatic transmissions

    The TV cable is attached on one end to the throttle linkage and on the other end to the transmission. As the throttle is depressed, the cable is pulled, causing progressively later upshifts at higher throttle positions. Additionally, when the cable is pulled a certain amount (ideally, when the pedal is completely depressed), the transmission, if possible, is made to downshift.
     
  20. This was helpful for me as well. Thanks all!
     
  21. XXL__
    Joined: Dec 28, 2009
    Posts: 1,861

    XXL__
    Member

    Please provide a link to this information. I'd like to contact TCI so they can correct it.
     
  22. Lot of BS on the TCI website then.
     
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  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,374

    gimpyshotrods
    ALLIANCE MEMBER

    No modern car has a TH350.

    It went out of production 32-years-ago.

    The cable on a TH350 controls downshifting when you stomp on the throttle. That is all it does. It does not even need to be connected, at-all.

    I have left them off completely, for customers who did not want/need them, mostly on 3x2 setups.

    The TCI info is flat-out wrong for a TH350.
     
    Budget36 likes this.
  24. This one might work fine if it gets full detent at full throttle. It does nothing for the first 1/4, 1/3 opening. You wouldn't do that on a 200/700.
    Also, the T400 outlasted the T 350 in production, too. Up to about 1992 in the P30 motor home (bread truck ) chassis. It NEVER had any kind of cable.
    TCI dis-info on the web.
     

    Attached Files:

  25. aussie57wag
    Joined: Jul 13, 2011
    Posts: 233

    aussie57wag
    Member
    from australia

    You could always get a mans gearbox with a clutch and you can choose when you change all your gears. You can even have more the 3 gears.

    Sent from my SM-T805Y using The H.A.M.B. mobile app
     
  26. My th350 trans recently started shifting a little late then all of a sudden it would not shift until 2800 rpm. 1-2 wasn't to bad but you had to be going almost 50 for it to go to third, I put it manually into second th heh shift it into 3rd and it still wouldn't shift until the 2800.
    It turned out to be a pinhole in the little 4 inch section of rubber line from modulator to hard line leading to the vacuum source. Interesting how a small loss of vacuum signal moved the shift point like that.
     
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  27. Stogy
    Joined: Feb 10, 2007
    Posts: 16,737

    Stogy
    ALLIANCE MEMBER

    When I first purchased the mine it shifted exactly as you describe...but I thought it was in the wrong gear or the shift kit...The first drive with the wifey (her first time in a Hotrod to boot) I thought it was in 2nd gear as it was reving away and not shifting so I nudged the shifter forward to find third and it popped into neutral then into reverse...wheels locked up we slid forward somewhat violently...I pulled back the stick quickly out of reverse and well lets say she wasn't impressed. The seat was not even bolted in to boot so it shifted forward with us...:confused:

    Fast froward to what was going on the modulator was not hooked up to vacuum (there wasn't a hose at all) and once that was done it shifted fine...but how those fellas drove it like that I don't know...

    @blazedogs is this just a recent thing maybe its fluid related. The other thing is perhaps look at shift-kits...maybe this will give you what you want. Oil change perhaps and as @swade41 said check your line for leaks and on more thing to think
    about is the vacuum source.
     
  28. F.O.G
    Joined: Oct 31, 2006
    Posts: 259

    F.O.G
    Member
    from Pacific,Mo

    Four revolutions is the max the adjuster can be turned on the TH-350 modulator, more risks
    damaging it. Could be 3 turns, I'm old can't remember and I'm too lazy to look it up, book is 80 ft
    away in the garage. Maybe later.
     

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