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Which brakes are right

Discussion in 'Brakes' started by SeanV, Jan 15, 2021.

  1. SeanV

    SeanV Member

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    Hey guys, hope y’all can help. I have a 1977 C20 Suburban Silverado, 2wd, auto with a 454 and the tow package. I went to replace the pads, rotors, drums and shoes. Every parts store I go to as well as online tell me the only brake rotors are 8 lug drums/rotors. My truck has 6 lugs front & rear. Of course not being a 17 digit VIN, no one can decode it. The truck was built in June 1977 so it’s pretty close to the 78 model year, if that matters.
    Can anyone tell me what I’m supposed to have, or what other 6 lug vehicle might match up? Thanks for your help.
     
  2. Goldie Driver

    Goldie Driver Full Access Member

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    6 lugs are half ton 4wd, so maybe try matching those parts to what you have.

    Seems like newer GM 2wd half tons have had 6 lugs, but I thought all square body 2wd half tons were 5 lug and 3/4 and up were 8, so who knows.
     
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  3. Blackbeard44

    Blackbeard44 Full Access Member

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    I would dissamble and bring pads and shoes in with me, parts store people these days will be of little use other than what the confuser says you need.

    if you can have a friend give you a ride to tje parts store with your parts for comparison that would be best.

    honestly unless your stuff is all toast I would try to keep as much as the original parts on the truck, new calipers are all from china, new brake drums the same. i recently went to change out my rear brake shoes and the new ones had less meat on them than my old ones did
     
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  4. Keith Seymore

    Keith Seymore Full Access Member

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    This is correct.

    Something is not right on the op's truck.

    K
     
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  5. Keith Seymore

    Keith Seymore Full Access Member

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    I can decode it.

    Post the VIN; just leave off or "X" out the sequential portion.

    K
     
  6. Blackbeard44

    Blackbeard44 Full Access Member

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    what your truck has currently, doesnt mean its what it came original with
     
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  7. bucket

    bucket Super Moderator Staff Member

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    Someone in the past has done some parts swapping for one reason or another.
     
  8. SeanV

    SeanV Member

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    Thank you all for the help. I’m starting to lean to the “wrong parts” installed on the truck before I got it.
    Kieth, the VIN is CCS267F203303. Thanks for the help.
     
  9. SeanV

    SeanV Member

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    Keith, the VIN is CCS267F203303. Thanks
     
  10. Ken B

    Ken B Supporting Member Supporting Member

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    on my 81 the parts store sold me the wrong calipers, I didnt research enough to know there were 2 different brake set ups for a 2wd.
    the first calipers were bigger and were like a 1/4 inch away from fitting.
     
  11. Keith Seymore

    Keith Seymore Full Access Member

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    Ok - the truck is reportedly a 1977 C20 Suburban Silverado, 2wd, auto with a 454 and the tow package.


    VIN = CCS267F203303


    I've a attached a VIN decoder card from this website (we used to carry these around in our shirt pocket):

    https://www.genuinegmparts.com/resources/vinlookup

    I'm also including the generic info packet from the GM Heritage Center archive, just for your future reference.

    https://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Suburban/1977-Chevrolet-Suburban.pdf

    From the card the VIN decodes as:

    C = Chevrolet (T = GMC)

    C = Conventional Cab

    S = 454

    2 = Series, ¾ ton

    6 = Sport Van, Wagon, Suburban

    7 = Last digit of model year

    F = Flint Assembly plant

    203303 = sequential portion, starting with 100001


    So – the VIN decodes pretty much as you would expect.


    K
     
    Last edited: Jan 16, 2021
  12. Keith Seymore

    Keith Seymore Full Access Member

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    Having said that, that leads me to believe somebody took your 3/4 ton 2wd Suburban and swapped in a set of 1/2 ton 4wd axles, both front and rear - or - maybe even more likely, swapped your 3/4 Suburban body onto a different 1/2 ton Suburban frame. At this point we don't have any idea what model year, so I'll post the brake system chart from 1986 (just because it is the most recent that still uses the C/K naming convention, and also because it is a nice format)*.

    The model code for Suburban is 10906 (1/2 ton) or 20906 (3/4 ton). The only choice for a 1/2 4wd Suburban brake system is JB5. From the chart below you can see the parts, by part number and size/dimensions, that created an '86 JB5 brake system.

    I'd use that as a starting point and see how they compare.

    You might also be able to pick some three character codes off the axle tubes, which might help us zero in on what model year axles were used.

    By the way, your apply system (booster and M/C) have likely not been changed. If you need parts for those the correct RPO would be JB6 or JB7 (for a vacuum boost; JDx for hydraboost).

    K



    *Also because I already had it scanned ;)

    86 K Truck Brake.JPG
     
    Last edited: Jan 16, 2021
  13. Keith Seymore

    Keith Seymore Full Access Member

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    If the 3/4 ton 2wd body was swapped onto a 1/2 ton 4WD frame, and you could find a partial VIN on the frame, we could also use that to help narrow down what you have.

    K
     
  14. SeanV

    SeanV Member

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    Two options you say? That’s odd, didn’t know know that. I ordered pads, rotors, calipers and shoes from R1 Concepts out of California. All the other parts fit and are working except the rotors. They will bolt to the spindle, they just have 8 lugs. Would the K10 components work where C20 parts were originally installed?
     
  15. Keith Seymore

    Keith Seymore Full Access Member

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    Nope.
     
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