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HELP...HELP...rebuilding my th400?????

Discussion in 'The Garage' started by blazindorito, Apr 26, 2005.

  1. blazindorito

    blazindorito 1/2 ton status

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    I went to have my th-400 tranny re-built. I told the guy I wanted a high performance tranny. He suggested I put PLANETARY gears? Do you recommend I put this in? The truck will be used mostly off-roading 70/30 and sometimes daily driver? The truck currently has 1-ton rear/front, 6" lift, 4:56 gear ratio, a mild rebuilt 350. Need help?
     
    Last edited: Apr 26, 2005
  2. blazindorito

    blazindorito 1/2 ton status

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  3. blazindorito

    blazindorito 1/2 ton status

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  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I always thought the panetaries were considered a hard part, not really something to upgrade from a performance stand point.

    I do know that the TH475 (motorhome version of TH400) uses straight cut planetaries as opposed to the TH400's helical cut, maybe he was talking about upgrading to them? If so, I don't see any reason not to but it's nothing you will ever see or feel when driving - they would strictly be a durablility/strength upgrade.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm betting he said "straight cut" planetary gears as used in the TH475.

    Stronger upgrade, but necessary? Folks that run TH400's on here are more qualified to answer that than I.
     
  6. sweetk30

    sweetk30 professional hooker Premium Member

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    if free or 50-75 bucks for it ya get them and it will be done. but if not no big loss to you. the friends i have have had no problems with stock setups. and as for a 400 swap from a th350 the first gear will be less than the 350 is. a well built 350 will hold up no problems in your truck. i ran one for 4 years and had a built 400 sbc with 38" tires 4.10 gears and 1 ton axles all of this in a long bed truck that was 6500 lbs on the scales.
     
  7. y5mgisi

    y5mgisi 1 ton status

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    Planatarys are a type of gear that most if not all auto trans have. Some t-cases have them too. Yes there are upgrade ones but id say wou wouldent realy need to upgrade unless you have mondo power. or just have money to burn. definetly not a bad idea just might be and unnessary expence.
     
  8. blazindorito

    blazindorito 1/2 ton status

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    I went to check out what he was talking about and yes, he is talking about the straight cut planetary gears. He said they would cost $300 - $400 dollars. I told him I would get back to him when I found out from you guys what you think if I did need them or not.
     
  9. kennyw

    kennyw N9PHW Premium Member

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    I'd say it is probably an unnessisary expense unless you have a 400+ HP motor?
     
  10. retroblazer

    retroblazer 1/2 ton status Premium Member

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    turbo 400

    The stock set-up is fine. I stepped up to the 300m input shafts this year, but we've run a blueprinted stock unit in the race truck with no problem. We're running 400 hp and beat it for hours. Save your money. The fact that the guy is recommending these parts means he doesn't really know what you're doing or is just trying to sell you stuff you don't need. I'd find somebody else. www.rafforacing.com
     
  11. blazindorito

    blazindorito 1/2 ton status

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    Thanks to everyone that took their time to answer my questions! I want to build it right and when you dont know what your doing what someone else telle you sure sounds right. Thanks again I just saved $400 dollars.
     
  12. sweetk30

    sweetk30 professional hooker Premium Member

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    no problem. and 400 bucks :shocked: :eek: :screwy: i can get you a whole th475 used for 1/2 that. good luck buddy:cool1:
     
  13. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    yah if he was just suggesting those planetaries then he was probably trying to sell you the new $300 gearset and another $100 on labor to install it..
    You really only need to check the planetaries clearance with a feeler gauge. i forget what the spec is off hand but something like over .020" clearance and you should think about replacing the planetaries.
     

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