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Need help choosing the right rotor

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blue85, Oct 17, 2001.

  1. Blue85

    Blue85 Troll Premium Member

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    I am doing a 14BSF install/rear disc conversion/8lug to 6lug conversion and I am kind of stuck on rotors. I have been planning to use 80's 1/2ton 4x4 front rotors, but they do not have a round inside dimension to mate with the axleshaft. They have an I.D. of 6 1/4" with "D" shaped bulges in the I.D. to accomodate the back of the studs that press through the rotor and into the front hub. So I would have to turn down the axle flange to leave only 3/32" between the outside of the stud hole and the O.D. of the flange or machine out the inside of the rotor until the thickness of the surface that is parallel to the axle tube is only 5/32" thick (to give me 1/4" outside the lug holes on the axle flange). I could find some compromise between these, but overall, I think that something would be a little thin.

    There is extra room between the outside of the "hub-type part" of the rotor and the inside edges of the pads, so I really just need something with that part moved out.

    This may be confusing, but what I need to know is:
    What kind of rotors come in the TSM kit for 6-lug 14BSF?
    What other kinds of 6-lug rotors are available?


    <font color=green>Does a Dyslexic Insomniac Athiest lay awake at night wondering if there's really a Dog?</font color=green>
     
  2. Blue85

    Blue85 Troll Premium Member

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    Is an 88+ chevy truck front rotor the one that I am looking for?

    <font color=green>Does a Dyslexic Insomniac Athiest lay awake at night wondering if there's really a Dog?</font color=green>
     
  3. Scooter

    Scooter 1/2 ton status

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    TSM recommends using the 88-newer front rotors on a 6 lug 14SF. Specifically they said to use the 1" thick version. There is a thicker one that is about 1.25" thick but it wont work right with their bracket and the car calipers. If you order the "kit" from TSM you will get the 1" thick 88+ rotors. Those are the rotors that I used for mine. I only had to file just a bit (maybe 1/16" or so) off the edge of the flange to get the rotor to completely fit over the flange. I imagine that you could use some rotors from a LD 3/4 ton 4x4 PU that was 6 lug but they're probably the same part (thats just a guess, I have not checked into that). You could also go looking through an Afco Racing or other circle track catalog. I'm sure you could find a hat to fit your axle shafts then choose whatever rotor would happen to fit that hat. Personally I dont think that I'd recommend that route though.

    The TSM brackets are also set up to use the small GM front caliper. The spacing for the caliper bolts is like 3.5" (vs. 5" for the large GM front caliper). I used calipers from an 83 Monte Carlo. I would recommend using a tap and chasing the threads in the bracket, that'll make it little easier when putting it all together.

    Also, I did not have to change the MC or the prop valve. Everything so far works very well with it and its absolutely amazing how much better it stops now.

    Scot in KC, MO.
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  4. Blue85

    Blue85 Troll Premium Member

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    Scooter,
    Thanks a lot. That's what I was looking for. Actually, I picked up some 90's 1/2-ton front rotors last night and I'm pretty sure that they are going to work. I am using backing plates and calipers from an 80's 1/2-ton front. This seems to work except for a slight interference problem with the tab on the back of the outer brake pad, which I'm sure will be fine to just grind down a little bit. These rotors are big on the inside (7 5/16"), but the index hole in the center is very small (not even 3 inches) so that will have to be opened up at least to the inside size of a stock 6-lug wheel (3 9/16").

    Now I am debating whether or not to have a ton of machining done to these 8 lug shafts or just shell out $200 for a set of new 6 lug shafts. Maybe I just need to make sure that a new 6 lug shaft is a drop-in replacement in case I ever break one of these.

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