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Thread: Well shoot! 6-Bolt vs 4-Bolt Crank/Flywheel

  1. #11
    4 Star General NDT's Avatar
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    No. Clutch has to have bolting surface and friction surface.

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    Quote Originally Posted by NDT View Post
    No. Clutch has to have bolting surface and friction surface.
    Got it ok. I think I am going to use the smaller flywheel from the 50s truck if I can get my hands on it and have a machine shop transfer the ring gear over


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  3. #13
    4 Star General NDT's Avatar
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    I needed a 6 bolt hole 270/302 GMC flywheel back in the 80's and it was hard to find then.

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    Quote Originally Posted by NDT View Post
    I needed a 6 bolt hole 270/302 GMC flywheel back in the 80's and it was hard to find then.
    The guy I got my donor motor from has the flywheel for the engine. Aside from counting the teeth is there any way I can determine this from the flywheel casting? They are both 14 flywheels


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    4 Star General NDT's Avatar
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    If the CCKW pressure plate bolts to it and the recess for the pilot bushing is the same, that may work fine.

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    If you have a 6 bolt flat flywheel, and it has been ground for the bigger clutch, you can use a 1974 Chevrolet Corvette clutch kit, all parts. I have a 1956 GMC civy 302 in one of mine and that is what fits perfectly! I asked on another forum about having 4 bolt flat flywheels made. I had found someone to make them if I could get 50 of them. People said the stoopidest things: 'I want to keep it original' (no one can see it). The "GMC" (CCKW) clutch is an odd design and has a tendency to fail. In failure mode, many times the diaphragm will twist and not be able to disengage. Great in a city.... All clutches, especially the CCKW original clutch should be adjusted so that the clutch completely disengages about 3/4" before the pedal hits the floor. The free play is just an indication of how worn the disc is. As the disc wears, free play will go from a lot to none.

  9. #17
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    Hi Crowem87

    I was hoping Dr Duce would chime in with information. If anyone is going to know the answer on a CCKW question it is him. At one time or another he has owned and worked on almost every variation of CCKW ever built.

    Cheers Phil

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    I figured I would revise this and post what I ended up doing... I had the original 4-bolt engine completely rebuilt. Ended up going with a 50s pulley so it does not have the hand crank pulley assembly anymore. Im ok wit that and excited with the build!https://uploads.tapatalk-cdn.com/201...cbcea9f47a.jpg


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