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Technical query for FED chassis builders, hypoid offset

Discussion in 'Traditional Hot Rods' started by Zig Zag Wanderer, Feb 5, 2014.

  1. Zig Zag Wanderer
    Joined: Jul 6, 2007
    Posts: 564

    Zig Zag Wanderer
    Member

    i'm using the terminology in the title of the thread to refer to the vertical dimension between the rear axle's pinon centerline and the axle centerline.

    the axle in question is the 57-64 Olds/Pontiac. the pinions on these axles are not in the same plane as the axles like a Ford Banjo, but are slightly below the axle centerline

    i think that the 49-56 axles will have the same dimension but i'm not real sure. 8 3/4 Mopar would seem to be very similar as it seems that a lot of FED's were very easily converted to them when the 49-56 Olds fell out of favor.

    9 inch Fords of course are very different because of their extreme deep hypoid configuration

    if anyone has a hard number for this dimension it would make some design work easier
     
  2. powrshftr
    Joined: Mar 29, 2013
    Posts: 4,550

    powrshftr
    Member

    Zig,
    I don't have the answers you are looking for,but I'm sure as hell going to keep my eyes on this thread,as I have learned something from every thread you've been involved with on the HAMB.
    Thanks for that gentle "tune up/awakening" you gave me on here a while ago too,on the altered thread.

    Just when I start to think I know everything,I fun out how fucking wet behind the ears I truly am....lol! :)

    Scott


    Posted using the Full Custom H.A.M.B. App!
     
  3. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,258

    dreracecar
    Member
    from so-cal

    Please explain what it is you are trying to do here.
    Since the motor/trans/pinion all have to line up , the difference in offset to the axle centerline only determinds how much it raises or lowers the chassie.
    The early Olds and the Chry are so simular that one can take the 489(case) 1 7/8 R&P and machine them to fit the Olds case.
     
  4. Zig Zag Wanderer
    Joined: Jul 6, 2007
    Posts: 564

    Zig Zag Wanderer
    Member

    Scott,

    i'm really NOT that sharp man... i get it wrong a lot. i'm just a fellow student here, soaking it all up like you. its good to talk to guys like you who are as jazzed about this stuff as i am.


    Bruce,

    i'm developing a cad drawing of an altered chassis. if i can get the dimension i can draw up the rear axle and determine some relationships.

    i can also draw up the motor plate too. nothing needs to be cut until i have hardware in hand but its easier to get things on "paper" so to speak for me.

    here is some rough teasers


    [​IMG]

    [​IMG]
     

  5. Zig Zag Wanderer
    Joined: Jul 6, 2007
    Posts: 564

    Zig Zag Wanderer
    Member

    its sort of a "legal" take on a Chassis Research r-16

    i want to keep the rails dead level like shown


    the unusual rear structure is body support for the tail-pan on my steel henry-j body.

    wheelbase is 101; an inch longer than stock
     
    Last edited: Feb 5, 2014
  6. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,258

    dreracecar
    Member
    from so-cal

    Chrysler 8 3/4 pinion offset is 1.835 down from axle centerline and 1.104 off center of the housing
     
  7. GearheadsQCE
    Joined: Mar 23, 2011
    Posts: 3,002

    GearheadsQCE
    Alliance Vendor

    Just for reference,

    A Halibrand V8 is 3"
    A Champ style (3/4 ton) is 3 1/2"
     
  8. Zig Zag Wanderer
    Joined: Jul 6, 2007
    Posts: 564

    Zig Zag Wanderer
    Member

    thanks Bruce, that's a start. i can draw an 8 3/4 Mopar and see how i like the placement
     
  9. Tarlo
    Joined: Dec 7, 2008
    Posts: 186

    Tarlo
    Member

    I like the style of the plans.

    This was my plan I drew up.

    It was done in Illustrator, not Cad, but Illustrator works to the mm so it worked well.

    My approach was to get all of the fundamentals of the chassis built, then drop the engine in. I basically got the carb level, which gives you the preferred angle of the OM block, then cut the engine plates accordingly and fitted it all to the chassis. It helps if you have the trans case bolted up too as you can find your diff angle from it.

    I had the 9" diff with brackets mocked up, but not welded, then adjusted its angle to suit the engine with as little angle going through the universal joints as possible.

    I'm yet to drive it but the set up rolls with no issues.

    My build thread might help to illustrate our "adapt the design as you go" method.
     

    Attached Files:

  10. Tarlo
    Joined: Dec 7, 2008
    Posts: 186

    Tarlo
    Member

    Also, I collected my essential parts such as engine/trans, wheel and tyre combo, front axle and full diff before I designed the chassis.

    That way I knew all of the basic measurements.
     
  11. Zig Zag Wanderer
    Joined: Jul 6, 2007
    Posts: 564

    Zig Zag Wanderer
    Member

    nice build Tarlo

    yes i understand the importance of having the essential parts. this "exercise" grew out of designing the torsion tube components and the need to determine the lay of length of the tabs that attach the front axle.

    wheelbase is a given 100 or so inches as i need to stay within the wheel openings of the henry j envelope.

    the front axle and torsion tube parts will be built first. a bare block, a line-up bar and rear axle will be used to build the car around them as per conventional tube-chassis/rigid rear construction.
     
  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,925

    gimpyshotrods
    ALLIANCE MEMBER

    "Take your time. Try not to forget. We never will. We're just a minor threat."
     

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