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Disc Brakes and Wheel Interference....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Greg72, Oct 10, 2001.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I am researching the swap to a D60/14FF in my 1st Gen K5, but I thought I'd post on the main board since the answer should be the same for all of us! I have seen and read about some situations where the disc brake calipers will need to be "ground down" to provide clearance for the wheels...

    I can't remember what the situation is that requires this.....I am fairly sure it's not a 14FF issue, or I would have seen it more often. My suspicion is that it's probably for the D60 front and perhaps a LARGE style of disc brake kit. Can anyone clarify this for me?

    Also, with respect to caliper-to-wheel interference.....is the problem because of using a 15" wheel (diameter is too small) or is it more a problem with the backspacing of almost ANY wheel that is used? It seems like a good excuse to go to a 16" wheel, but there really aren't very many tire choices compared to 15" wheels......16.5" wheels have LOTS of tire choices, but are generally considered inappropriate for "low-tire pressure" offroading.

    If anyone can help me "fill in the blanks" in my K5 knowledge, I'd appreciate it! [​IMG]

    -Greg72
     
  2. outlaw612

    outlaw612 1/2 ton status

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    The caliper/wheel clearance issue is when youre trying to run a 15" wheel on a d60/d44axle or a 14b with the reardisc conversion. The calipers must be ground down alot. The 15" diameter of the rim is the problem. I dont think the backspacing will make any difference, the caliper will still need to be ground.

    <a target="_blank" href=http://www.geocities.com/outlaw613/K5.html>http://www.geocities.com/outlaw613/K5.html</a>
     
  3. rich

    rich 1/2 ton status

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    Outlaw612 is correct - the interference I know of is with the disc brake calipers on 8-lug Dana 44 front axles or Dana 60 front axles with 15" rims. I have no experience with the disc brake conversion on a 14-bolt, so I can't comment on that.

    The interference is on 15" wheels only, not on 16" or 16.5". I didn't want to run a plain 16.5" wheel because of the lack of conventional bead on 16.5" rims, making it easy for a tire to slip off the bead at aired-down tire pressures. But I was planning on beadlock rims anyway, so that would have been OK. But then I already had some 36" tires for 15" rims, so I wanted to stick with 15's, just like you, for the greater tire selection.

    I talked to Stephen at OffRoadDesign about this. He said that since I was ordering custom wheels anyway (since I was getting beadlocks), I should specify a 3" backspacing. This should allow a 15" rim to clear the caliper, and may only require some LIGHT grinding to the caliper.

    The only problem with this is it makes the wheels stick out the sides of the truck farther, which is good for stability, but hard on wheel bearings and ball-joints. My '76 K5 sees the street only on the way to the trail, so this is not really a concern for me, but if it was my daily driver, that would suck.

    Some people on this site have made standard backspacing (4"-3.5") 15" wheels work by grinding a lot off the caliper. Stephen at ORD recommended that I not grind the caliper, so I didn't.

    If I were to do this on my daily driver, I would get 16" rims with standard backspacing so I wouldn't have to worry about my wheel bearings or ball-joints. If it is mainly an off-road vehicle and you don't mind the wheels sticking out farther, then get 15" with 3" backspacing, if you want to stay with 15" for the tire selection. 16.5" rims have almost as good tire selection as 15", if you can live with the lack of strong bead retention at low tire pressures, or if you are getting beadlocks.

    By the way, the only company I could find to give me 3" backspacing in a 15" 8-lug rim was Stockton Wheel. But it took me 4 months to get my wheels from them, and they made no apologies about it taking that long (was only supposed to take 6-8 weeks). Plus it cost $200 per beadlock rim, plus like $150 shipping.

    Hope this helps!

    Richard
    Raleigh, NC
    '90 K-5 Blazer - stock, daily driver
    '76 K-5 Blazer - 14-bolt FF, 4.10's, locked front and rear, 36's, SM465/NP205
     
  4. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I believe that one might experience clearance issues with a D60 (w/large brake rotor type) and 16" rims also! My D60 almost touches my 16.5" steel rims by about 1/4"... the issue is not necssarily the calipers themselves, but the brackets that are used to position the bottom of the calipers. The two bolts that hold the small "I Beam" piece in are the closest parts that I have to my rims... otherwise 16" might work.

    And as for the rear disc conversion clearance thing - The conversion uses discs from the D44 axle that causes clearance problems in the front, so assuming your rims are all the same inside diameter [​IMG], then the rear-disc converted trucks will have clearance issues too...

    The only thing I have seen to help the situation, is huge spacers, which only help in that you have to shave only half your caliper instead of the entire caliper...

    Hope this helps...

    <font color=red>GOT MUD???</font color=red>
    <a target="_blank" href=http://24.10.209.54/bigolk5.htm>http://24.10.209.54/bigolk5.htm</a>
    454/TH400/NP205 - 14BFF/D60/w/ 4.10s
     
  5. wayne

    wayne 3/4 ton status

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    Doing this know. Putting 15x10 with 4 1/8 backspacing on a Dana 60. Those calipers are thick and after the grinding they are still thicker then a 10 bolt caliper.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     

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