TH475 questions

Discussion in 'Drive Train and Tires: Selection and Modification' started by iain stuart, Jan 26, 2019.

  1. iain stuart

    iain stuart New Member

    I just bought a TH475 transmission which comes with a drum parking brake attached, and the yoke is a bolt on type. The transmission comes from a motorhome with only 35k miles on it. These transmissions are installed for pretty heavy use, so have straight cut planetary gears- a bit stronger, but possibly a bit noisier. However, this trans is going behind a blown BBC, so a little gear whine shouldn't be too much of a burden.

    Now, what I want to know is exactly what the situation is regarding changing from bolt on to slip on yoke. On the interbabble there are conflicting stories, but the consensus seems to be that a slip on yoke that has the splines counterbored into the yoke by about an inch to 1.5" is the answer. And then you see, "except for motorhomes". So, what's the story here?
  2. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Remove the park brake drum.
    Its supposed to be a Rollerized Needle bearing output instead of a Lead babbit bushing in the tail housing. Just like a Powerfull drag car with a custom built Turbo 400 or Powerglide. What I have been told. Regular GM or aftermarket TH400 slip yoke fits.

    I used a Chevy Truck Th400 in my 63 Pontiac Gp. Used a TCI transmission adapter plate for BOP engine to Chevy TH400.
    The truck yoke comes right off removing the single retaining bolt.
    The output shaft is splined like any other TH400 trans.
    Type C casted tailshaft housing used on most Th400's.
  3. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Guys have rated the Straight Cut Turbo 400 planet gearsets at 1,000 Hp.
    They were designed for real heavy vehicles for pulling and no internal thrust for thrust washers to fail.

    The factory installed Helical cut TH400 Planets are rated for up to 4,000 HP drag use as is.
    So the Normal TH400 gearsets are better.

    Both are bullet proof for most.

    There was a 4L80E also made with Straight cut planets too.
    Used behind the Factory 496 BBC installed into Ryder Moving trucks only.

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