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Still very confused on which 14 bolt FF to get.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by shum1, Feb 7, 2001.

  1. shum1

    shum1 1/2 ton status

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    Man I, thought this would be cut and dry but I guess I'm missing something. Here's what I have now: 1990 1/2 ton suburban. GM 10 bolts. I want to do the 14 bolt conversion, Why is it nessesary to obtain the backing plates from the 14 bolt SF axle? Why cant you use the one that comes with the FF? Also, their are 3 drum sizes for the 14 bolt FF. 13x3.5, 13x2.5 and 11x2.5. I havent heard mention of this on this site before. The 13 incheres are significantly more expensive than the 11's and so are the parts. I have new 15 inch tires so I am assuming that the 11" drums are my only option. I could take the tires back and go 16" if there is a great benefit to going with the 13" drums. Also there seems to be an issue of left or right parking brake. Thanks.
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    The only thing iI can help you with is that I have heard that if you use a 3.5" - 3" or less back spacing, you can run the larger brakes.

    Also, the larger brakes will be better to stop your Burb..

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The different brake sizes were 11x2.5 for 3/4 ton, 13x2.5 for one ton, and I'm guessing the largest size was for a dually application, i'm gueesing because I thought there were only 2 different brake sizes.
    You should save yourself moving the perches and look for a 3/4 ton version. It will have the 11x2.5 brakes on it. As far as the backing plate issue, I beleive that has to do with the parking brake set-up on the axle not matching up with the set-up on the truck. My 14 bolt FF came from a '76 3/4 ton 2 WD and went into my 81 Jimmy and it bolted right up and the parking brake cables worked just dandy. Before you go shopping for a 14 take a few pics of your backing plates and E-brake assemblies and then you can compare it with the prospective donors. I have 8 bolt 15" rims on mine right now and they clear the drums by a lot with the 11" brakes. The other thing is that a 2WD 14 bolt will need to have the shock mounts moved up a couple of inches, they are lower than the 4WD version.

    Rene

    [​IMG]
     
  4. Boss

    Boss 1/2 ton status Author

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    You can run 15" wheels over the 13" brakes with any backspacing.
    Boss

    <A target="_blank" HREF=http://www.boss.coloradok5.com>http://www.boss.coloradok5.com</A>
     
  5. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Ok, sit back and read. 14FF come in three different brake drum sizes. 11.15x2.75, 13.00x2.5, and 13.00x3.5. Only the 13.00x3.5 is on the one tons. The other two sizes are for the 3/4 tons. Yes, they used both sizes. Guess they were options from factory. 14FF were used in 3/4 ton versions up to 82 and 14SF were started in 81. Again, the FF was options for 81 and 82. The SF was standard equipment. The 14FF was also standard equipment on the one tons. On the backing plates, you need plates from an 83 or newer. If your 14FF is older than 83, you need to find plates to make the parking brake work. All trucks up to 82 have equal length cables coming out of the plates and going to a bracket under the forward part of the rear springs. 83 and up have the passenger side cable running over the pinion/yoke to the driver side to hook up to the bracket with the driver side cable. The difference in the plates are the holes where the cables go into. 82 and older use two bolts to hold the cable assembly to the plates, and 83 and newer have clamps on the cable that just hold themselves to the plate holes. You cannot make either work for the other. As for 15" rims, they will fit ALL 13" drums very easily. When someone says 13" or 11", they are referring to the inside diameter of the drums. You will have plenty of clearance with the 15" rims on 13" drums.
     
  6. shum1

    shum1 1/2 ton status

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    K30guy: wasnt sure if my private went through so I'm listing here.
    Hey, thanks a million for that detailed response to my 14 bolt question. I have only one more question. You explained the differences about the drum sizes. If I use a 1982 or older 3/4 ton 14FF and I need the 1983 or newer backing plate, are there different size backing plates that correspond to the size drum I get? For example, If I use the 13x2.5 drums from the older 3/4 ton axles then do I look for the new plates from the 1983 and newer 3/4 ton 14SF axles? Or do I use plates from a 1983 or newer 1 ton axle? Thanks
     

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