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Thread: Have a question on a th400 I am rebuilding.

  1. #1
    Fuel Injected!
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    Have a question on a th400 I am rebuilding.

    So I have the trans mostly disassembled and right now I am making a list of the stuff I will need. Anyway I noticed the reaction carrier that the reverse band gripes on has grooves worn into it. I have read online about people getting the reaction carrier lathed smooth again. Should I have it fixed or should I buy a new reaction carrier? It might be hard to tell in the pictured but the middle of the reaction carrier is where the grooves are the worst.
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  2. #2
    Fuel Injected!
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    I went to a machine shop today and talked to them about getting this part machined. They said I should just run it as is. The new band has the same type of grooves in it. He said that if he machined it flat again that because of the grain structure of the steel it would cause the band and carrier to wear quickly again and probably have a similar grooved surface. Because the current grain structure of the steel is already changed the new band and old drum wont wear nearly as bad together. So I am going to leave the reaction carrier as is.

  3. #3
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    So I took the pump apart today to make sure everything is in spec and the oil pump cover is warped so it will be machined flat again. The other side with the gears in it is flat so that does not need to be machined. Now the issue i have is that the clearance between the drive gear and the small crescent is out of spec. Spec says .002" to .0075" and my clearance is at .009". where the gears ride in looks good with no burs or ridges. Do you think a new set of pump gears would solve that clearance issue? I would like to use the pump I have and not buy a new one. Everything else looks good so if i can get the gear in spec and the cover machined i can put it back together.
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  4. #4
    Fuel Injected!
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    The th400 came with the grooved carrier, the 4L80E had both a grooved and smooth carrier and band sets. The pump wear will be one of 2 places, either the crescent or the body. Can you wiggle the outer pump gear in the body?
    If it don't fit force it, if it don't force fit f&%@ it!

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