The ST400 / TH400 variable Pitch Stupid Question Thread

Discussion in 'The "Juice Box"' started by Dan Hach, Oct 12, 2020.

  1. Matt69olds

    Matt69olds Well-Known Member

    If at all possible, I prefer to set end play a little on the tight side of spec. My thinking is endplay will normally open up as things wear, and the less things move around the better the sealing rings will seal.

    I’m pretty sure HydraMatic changed end play specs a couple times over the years, always tightening the specifications.

    If the endplay is in the middle of spec, I wouldn’t worry about getting it exact.
     
  2. Dan Hach

    Dan Hach Well-Known Member

    Ok, I got my end play set to about 0.012. Pretty "middle".

    On to the next dumb question. Ron Sessions is pretty emphatic in his book that it's necessary to upgrade to the newer style center support. This is the one with the 0.040" think lower spacer ring. My 66' doesn have that. I found the right center support, but the guy didn't have the spacer ring. So installed the old center support with no spacer ring. But now I'm second guessing that decision.

    I've been looking for a spacer ring and I can't seem to find one. Does anyone have one? If so, I'm happy to buy it. Alternatively, is this really a big deal? I'm at a point where it isn't a big deal to go back and replace the center support. I'm actually getting pretty good at assembling this thing. However, once it is in the car, it will be a much bigger deal. Thoughts or comments?

    Thanks,
    Dan
     
  3. BRUCE ROE

    BRUCE ROE Well-Known Member

    I agree with Ron, get the ring. You might try Automatic Transmission Parts
    (ATP) that seem to sell about anything. So many 70s TH400s got scrapped,
    there are a lot of parts around. My own method was to use an early 70s
    trans and convert it to switch pitch. Bruce Roe
     
  4. Dan Hach

    Dan Hach Well-Known Member

    Thanks Bruce, l keep looking. I may have found one on ebay. I'm waiting to hear back from the guy.
     
  5. Matt69olds

    Matt69olds Well-Known Member

    While I can’t recall ever tearing down a early 400 with case wear from the center support, HydraMatic felt the cost justified the production change. There were millions more transmissions made with the wear ring than without, I would think they would be pretty easy to find.
     
  6. BRUCE ROE

    BRUCE ROE Well-Known Member

    In case you have not already gotten one, I found a spare 40 mil case ring here. Bruce Roe
     
  7. Dan Hach

    Dan Hach Well-Known Member

    Thanks Bruce. I found one yesterday. I should be back on track this weekend.
     
    Last edited: Oct 29, 2020

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