TH400 setup woes

Discussion in 'Transmission & Driveline Topics' started by Lee45, Dec 11, 2017.

  1. NOT A TA

    NOT A TA Veteran Member

    191
    48
    Feb 12, 2009
    Delray Beach Florida
    One problem I've run into with B&Ms (especially Megashifters and Quicksilvers) in 2nd gen F bodies is people want to use the stock auto shifter cable hole in the trans tunnel without modifying and it causes the cable to have a tighter bend than it likes between the shifter and trans tunnel. As it starts to deform the cable housing it throws the adjustment off and eventually the cable housing splits. Once it splits you're lucky if you can get it into a forward gear to get it home without having someone manually switch the selector arm on the transmission under the car while you stand on the brake.
     
  2. Lee45

    Lee45 Member

    63
    5
    May 28, 2017
    My cars had multiple manual and automatic transmissions in it so I just have a large contoured plate that I bolt on, just make a new one for each setup. Works fine, looks okay.
     
  3. 1980RS

    1980RS Veteran Member

    1,959
    94
    Jun 17, 2006
    MN
    From what I remember the adjustable vacuum mod just has to do with the shift firmness, I used to mess with the governor gears to get it to shift where I wanted it to. Most of the time I ended up with the stock gov. and just shift it manually, more fun that way.
     
  4. Jimmiee

    Jimmiee New Member

    3
    0
    Jun 1, 2015
    Reno, NV
    The vacuum modulator mainly controls line pressure. It will raise the shift points a little but had little effect at light to medium throttle. Like mentioned above the governor controls the shift points. You can dial in the 1-2 and 2-3 shifts with a governor kit which gives you light weights and springs. The lighter the weight the later the shift. The weight flys out with centrifugal force and works against line pressure and the spring. The instructions explain where to start. The good news is the governor is very easy to get to and there's no mess like there is when dropping the pan. You can get the kit from Summit or Jegs, Ebay, etc. Here's a link:
    https://www.summitracing.com/parts/...MIhNas6_WW2AIVXbnACh1FaQkrEAQYAiABEgKMF_D_BwE
     
  5. Fbird

    Fbird Veteran Member Lifetime Gold Member

    2,806
    261
    Feb 12, 2011
    atlanta, ga
    the 4200 converter will cause a problem with your light throttle shifts..... i couldn't imagine it "lurching" in any gear (regardless of what your diff is) with that kind of converter.... especially a th400, unles your idle is 3500..
    unless you are running some 285 @ 50 duration 600 lift roller.... you should probably be using a 2000- 2400 rpm converter.... then you will still feel 1-2nd under light throttle to be a bit sloppy (it's a 400..) even with 2-3 being "noticable".
     
  6. Lee45

    Lee45 Member

    63
    5
    May 28, 2017
    street strip car, Crane and tci both recommended the converter. I like it, and From what I've been told the hard shift into reverse in first is a combination of high idle (1100 in gear) and low vacuum. And it was much worse before I adjusted the modulator, its noticeable but not ridiculous like it was.
     

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