Wheel info for anyone interested....(Chuck)

Discussion in 'Original Drivetrain Topic' started by Budz, Apr 11, 2004.

  1. Budz

    Budz Veteran Member Lifetime Gold Member

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    I know there have been discussion's about the 5 spoke wheel's, and the different size stem hole's used on different year wheel's, and when they changed.

    This is just some info from the wheel's I have aquired, and thought some of you may be interested.

    An (*) mean's I couldn't read it.

    Note: There are two June 5th,1970 wheel's with the 5/8" hole, and one June 1st, 1970 wheel with the 13/16" hole....Go figure [​IMG]


    SIZE.........HOLE SHAPE......MARK @ HOLE.......DATE CODE

    1) 5/8"............oval....................GM............K10 4 13 AU.............= April 13th 1970
    2) 5/8"............oval....................GM............K10 4 13 AU.............= April 13th 1970
    3) 5/8"............oval....................GM............K10 6 5 AU..............= June 5th 1970
    4) 5/8"............oval....................GM............K10 6 5 AU..............= June 5th 1970

    5) 13/16".........oval....................GM D.........K10 6 1 AU..............= June 1st 1970
    6) 13/16".........oval....................GM............K11 10 4 AU.............= Oct 4th 1971
    7) 13/16".........oval....................GM E.........K12 3 28 AU.............= Mar 28th 1972
    8) 13/16".........oval....................H..............K14 7 19 AU.............= July 19th 1974
    9) 13/16".........oval....................*..............K14 7 19 AU.............= July 19th 1974
    10)13/16"........oval....................GM A..........K12 1 6 AU.............= Jan 6th 1972

    11)1"..............round..................M 3............K18 11 17 AU............= Nov 17th 1978
    12)1"..............round..................19 C...........K19 3 20 AU.............= Mar 20th 1979
    13)1"..............round..................19 C...........K19 3 20 AU.............= Mar 20th 1979


    ------------------
    Buddy
    1970 Z/28 and
    2002 35th Anniversary SS









    [This message has been edited by Budz (edited April 12, 2004).]
     
    Last edited: Sep 21, 2017
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    This is great stuff. For a while now, we have thought that the change from 5/8 to 13/16 occurred sometime in June. Your numbers confirm this, but it does appear that both sizes existed at the same time, at least for a few days. I guess this isn't unusual because the manufacturer probably had more than one machine to stamp them out, and it would make sense to change the machines one at a time to keep production running every day. I hope Chuck sees this.
     
  3. Budz

    Budz Veteran Member Lifetime Gold Member

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    Gary, glad to be of some help. It's interesting trying to nail this stuff down.

    I finally decided to spend the time to check them all today. Not much else to do with the wife and kids all sick at the same time.

    I figured I'd be safe hanging out in the garage. [​IMG]

    Damn.......just realized I forgot to check the offset on the front lip of all these wheel's. Dohhhhhhhh. Somebody kick me. [​IMG]

    Buddy
     
  4. CamarosRus

    CamarosRus Veteran Member

    OK........I've seen this ......great work Buddy.....Somebody if not myself needs to go back and translate the month and days on these........I'm NOT familiar with seeing the GM and a letter stamped before the K10 which is Kelsey Hayes Plant #1 1970......
    Anyway This needs to be defined a little better,m, but it would seem like Jan-May 70 Z's (Norwodd and LA???) should have 5/8 wheels....Other than the spare, I'm not expecting ANY Top notch resto Z to be pulling a Trim Ring for inspection.....so I'll take the spare for all five as correct...Chuck
     
  5. CamarosRus

    CamarosRus Veteran Member

    SIZE / MARK @ HOLE / DATE CODE

    1) 5/8" oval / GM / K10 4 13 AU 70 April 13
    2) 5/8" oval / GM / K10 4 13 AU 70 April 13
    3) 5/8" oval / GM / K10 6 5 AU 70 June 5
    4) 5/8" oval / GM / K10 6 5 AU 70 June 5

    5) 13/16" oval / GM D / K10 6 1 AU 70 June 1
    6) 13/16" oval / GM / K11 10 4 AU 71 Oct 4
    7) 13/16" oval / GM E / K12 3 28 AU 72'Mar 28
    8) 13/16" oval / H / K14 7 19 AU 74 Jul 19
    9) 13/16" oval / * / K14 7 19 AU 74 Jul 19
    10)13/16" oval / GM A / K1* 1 6 AU ? Jan 6

    11)1" round / M 3 / K18 11 17 AU 78 Nov 17
    12)1" round / 19 C / K19 3 20 AU 79 Mar 20
    13)1" round / 19 C / K19 3 20 AU 79 Mar 20

    That one 13/16 with June 1 and the June 5 with 5/8 holes is confusing
     
  6. Budz

    Budz Veteran Member Lifetime Gold Member

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    Ok....wheel #10 is a '72 wheel and I corrected the list. Wheel #9 is the same build date as #8, so I assume the stamp would also be an "H".

    Buddy
     
  7. Budz

    Budz Veteran Member Lifetime Gold Member

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    Chuck, I see it the same as Gary. There must have been multiple machine's making the wheel's.

    After the first machine was re-tooled, it would have been producing the "New" 13/16" wheel's at the same time the machine's that hadn't been re-tooled were still making the "Old" 5/8" wheel's.

    If it took a week or two to change all the machine's, the last machine changed would have made 5/8" wheel's dated AFTER the first 13/16" wheel's were made.

    Hmmmmmmmm....I think I just said the same thing twice.

    Buddy
     
  8. jacsey 70Z

    jacsey 70Z Veteran Member Lifetime Gold Member

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    Buddy, How about this angle, If you look at the wheels they are two piece, the date next to the valve stem hole is the date the main rim was made(because they couldn't of stamped once it was welded together). If you look at the outside ring (the part with the slotted valve stem hole 5/8" etc.) it was stamped at a different time then the main rim thus the stamp by the slotted hole. Who knows what happens when the rims are being run separate. When they came down and said the slot was to close to the valve stem they put a different size punch in the die and kept going, they could have got mixed, or the stock was used up completely before they started using the 13/16 holes. It all comes down to what part they grabbed when the outside ring was welded to the rim. And how long the main rim proceeded the ring. Now I'm getting confused, just a thought!!
    Jack
     
  9. Budz

    Budz Veteran Member Lifetime Gold Member

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    FWIW.........

    The first 10 wheel's in my list above, 70-74 wheel's, have the inner lip at the trim ring raised about 1/8" above the the outer lip. The remaing three, 78 & 79 wheel's, have the inner lip about 1/8" lower than the outer lip. Hence....somewhere between 74 & 78, they changed the lip design.

    ------------------
    Buddy
    1970 Z/28 and
    2002 35th Anniversary SS
     
  10. Gary S

    Gary S Administrator Lifetime Gold Member

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    Bismarck, North Dakota
    You are correct. From what I've seen, the oval hole wheels have the raised inner lip, and the round hole wheels have the lower sitting lip. I don't have any idea why GM chose to make these changes, but they did.

    We documented as much of this as we could find on Stegmiller's page years ago, and from what we are seeing, the wheels still seem to fit these specifications.

    http://www.nastyz28.com/2gcog/stegmiller/z28_wheels.htm
     

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