Muncie 4-speed or 5-speed Conversion?

Discussion in 'Transmission & Driveline Topics' started by Billy73, Aug 2, 2019.

  1. Jeffsz28

    Jeffsz28 Member

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    I have an 81 Z with 3.73 gears and I swapped in a TKO 600 with the .82 OD rather that the .64.
    My friend has a 69 Firebird with 3.73’s and he had swapped in the TKO 600 with the .64 Od. On the highways here in Florida the .64 was great, but those highway jaunts were just from one exit to another, 99% of the time his ‘bird is street driven, and that’s were the .82 shines.
    Driving his firebird, it felt like there should’ve been a gear between final drive an the .64. Anything under 55 would seriously lug the engine. With my .82 setup, 70mph is 2600 rpm’s for me (255/60/15 rear tires).
    My point in all this jabbering is that you should consider how the car is driven before dropping 5k (I bought a whole conversion kit, and yes it fits PERFECTLY!)
    IMHO, I’d take the .82 over the .64..
     
  2. Jeffsz28

    Jeffsz28 Member

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    One more thing, both our cars use Holley terminator efi kits so and are extremely well tuned. The Firebird originally had a carb on it and the .64 OD on the street was miserable...
     
  3. C4Racer

    C4Racer Veteran Member

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    T56 magnum has both a .8 and a .64 so you don’t have to pick just one. Agree .8 is great for rural highways or a short blast on the freeway or when there is traffic on the freeway. Then if you ever take a longer highway trip the .64 is available. I don’t use it much so far but it’s nice to have. Cost of a magnum is same as a TKO anyway.
     
  4. Jeffsz28

    Jeffsz28 Member

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    I seriously considered the Magnum but what stopped me was that I didn’t want to have to modify the tunnel. The Tko was such a drop in that one would think it was available from the factory!
    Agreed though, the Magnum gives the best of both worlds. There’s occasions when I wish I had an extra OD gear...


    *I wanted to add to the general conversation that I went with the stock type mechanical clutch linkage. The Firebird has the hydraulic clutch. No comparison the hydraulic is MUCH smoother, but I like the tactical feel of the old school setup. But man, that hydraulic clutch is butter smooth :)
     
    Last edited: Aug 17, 2019
  5. C4Racer

    C4Racer Veteran Member

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    You can do mechanical linkage with T56 too. The tunnel cut is not that big of a deal one way or the other in my mind. Even if it’s an original Z28. Just keep the section you cut and weld it back in and refinish it if you ever return the car to stock. Which is probably unlikely for most of us.
     

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