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621 Bellhousing clutch fork question

Discussion in 'The Hokey Ass Message Board' started by choppedsled, Jan 17, 2012.

  1. choppedsled
    Joined: Jun 2, 2007
    Posts: 301

    choppedsled
    Member
    from Spokane WA

    I'm running an early 621 bell on my 283 with a Wilwood slave. 11 in clutch, short throw out bearing etc. I picked up my current clutch fork with the slave as they recommended it. But with the throwout bearing resting against the pressure plate the fork nearly hits the opening in the bell, hardly any room to actuate the clutch. So, what fork was used with the 621 bellhousing? And is that what I'm needing?
     

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  2. SASROD
    Joined: Feb 7, 2007
    Posts: 136

    SASROD
    Member

    Attached Files:

  3. choppedsled
    Joined: Jun 2, 2007
    Posts: 301

    choppedsled
    Member
    from Spokane WA

    Thanx, I've got a long bearing showing up this morning so I'll give that a look. My brother in law has the original fork as pictured above. I want to see how it compaires to the fork I have. They are substantially different looks wise. It's probly where I should start though, as GM designed it, then fiddle with the T/O bearing if needed.
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 51,464

    squirrel
    Member

    The bearing needs to match the pressure plate. Short bearing with a 3 finger or bent diaphram, long bearing with a flat diaphram clutch.

    What pressure plate do you have? post a pic if you're not sure
     

  5. choppedsled
    Joined: Jun 2, 2007
    Posts: 301

    choppedsled
    Member
    from Spokane WA


    Bent diaphram, Zoom kit from Summit # ZZZ-MU1877-1B. The fork I have is 15592270, I believe a GM #?

    Correct stud ball, 4.75 in from engine block, correct?
     

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  6. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,074

    2OLD2FAST
    Member
    from illinois

    Went thru this 12 years ago only w a 3-finger B&B pressure plate.. There are 2 pivot ball lengths & 3 throwout bearing lengths, also either square-edged or round edge TO bearings, took many calls & exchange of parts to get the right setup , hang in there , the parts are available, just alot of trail & error..

    dave
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 51,464

    squirrel
    Member

  8. choppedsled
    Joined: Jun 2, 2007
    Posts: 301

    choppedsled
    Member
    from Spokane WA


    Yup, that's the fork I've got. I have the correct original on the way, should have it tomorrow and start from square one. Way to many options since the good ol days.

    One more question that I'm going to post on the main board. How much space is needed between the end of the trans bearing retainer and the clutch disc hub? My setup looks to be tight, 3/16". Is that enough to release the clutch?
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 51,464

    squirrel
    Member

    That should be plenty. The clutch disk should move back very little when it's released, probably 1/16" at the most
     
  10. choppedsled
    Joined: Jun 2, 2007
    Posts: 301

    choppedsled
    Member
    from Spokane WA


    Thanks for all the help. I'd second guess all day long and then some otherwise.
     

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