Needing some 12 bolt advice/help

Discussion in 'Transmission & Driveline Topics' started by Shizzle, Mar 1, 2018.

  1. Shizzle

    Shizzle Veteran Member

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    Aug 1, 2012
    oak lawn, illinois
    The motor is a GMPP 454HO, stock now but hope to add a different cam and heads (goal is to have 500RWHP).
    Trans is a ST-10 2 groover, but have dreams of a TKO600.
    Car will mainly be a local cruiser, but occasional highway.

    What gear ratio would be recommended? It has 4.88s now which I think is way too low for anything other than 1320' at a time.

    It has a 3 series posi, with the 4 springs instead of the "Z" spring, how do you tell if the clutches are still good? They still look like a nail file but have some of the phosphate(?) coating worn away. Or would it best to just replace them?

    The car is no where close to being driveable, but I am in a major rut on getting anything done on it (I haven't really touched it since August of '16) and need to get something accomplished just to keep from getting discouraged and abandoning it.

    Thanks
    Shawn
     
  2. 1980RS

    1980RS Veteran Member

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    Jun 17, 2006
    MN
    I always like 3.55's with my 4 speed cars that had 454's In them.
     
  3. big gear head

    big gear head Veteran Member

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    Jul 30, 2001
    Central City, Ky.
    You could run a 3.31 and be fine in town and highway. If the clutches still have a dark band around the inner and outer edges then they can be used. You need to shim them for correct preload. You could also swap in the 400 pound springs if you want a little extra grip.
     
  4. Shizzle

    Shizzle Veteran Member

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    The springs are yellow now?
    What is the easiest way to install them?
    I clamped the plates & springs in the vice and ran zip ties thru the holes and it still sucked!
     
  5. Gary S

    Gary S Administrator Lifetime Gold Member

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    The GM service manuals show a procedure for checking the preload on the clutches. You need a torque wrench (beam type are easiest for this job) and a custom tool to attach to the wheel studs. You can weld up one of these tools in your garage.
    This test will give you an idea just how good the clutches and springs are still holding
     
  6. big gear head

    big gear head Veteran Member

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    Jul 30, 2001
    Central City, Ky.
    If the springs are yellow then they are the 400 pound springs. It's very difficult to install the springs and plates with the ring gear installed, and probably not possible with the 4.88. I use Channel Locks to compress the springs and push them in the differential.
     
  7. Shizzle

    Shizzle Veteran Member

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    oak lawn, illinois
    Ohh I proved you wrong installing the springs & plates with the ring gear on!
    It would’ve been MUCH easier to do it with the carrier on the bench and ring gear off. The zip ties actually worked pretty well.
    I couldn’t tell you how many times I went chasing for those springs in the garage!
     
  8. Shizzle

    Shizzle Veteran Member

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    oak lawn, illinois
    Would the 3.31 play well later on with the overdrive of the TKO600 in the future?
     
  9. big gear head

    big gear head Veteran Member

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    Jul 30, 2001
    Central City, Ky.
    Depends on what the first gear ratio is in the TKO, and how low the engine RPMs can be in overdrive. If the transmission has a first gear ratio around 2.9 and the engine has good low end torque then it would be great.
     
  10. Shizzle

    Shizzle Veteran Member

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    Aug 1, 2012
    oak lawn, illinois
    Cool, I will just have to keep that in mind then when I eventually get the TKO, being a BBC low end shouldnt be a problem.
     

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