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There's a LOT of difference between 3" and 4" backspacing!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by laketex, Aug 11, 2003.

  1. laketex

    laketex 3/4 ton status

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    There\'s a LOT of difference between 3\" and 4\" backspacing!

    Just bought new 35" MTRs on 15x8 steel rims to replace my 36" Mickeys on 15x10s. I had bought the new ones from 4WPW in the 2.75" backspacing variety, but when they got here they were 4.25" bs. So I'm thinking great, it'll tuck them under even more, just what I was wanting in the first place! Happily, I change the back tires complete with the chrome centers and nuts...yahoo, the buldge is right even with the bodyline. Perfect. Go up to the front and the tire hits the caliper. Crap. Measure the old rims. 3" backspacing. Ut-oh...so for a week I drive the truck like that with the sweet tires in back and the wide arse mickeys up front. Nice hoopty! /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif

    I get over to Dan's house last night thinking I could grind a couple ears off the backing plate and be all good. 3 hours later, I had created a shoulder in each caliper and ground down maybe 1/2" of meat off caliper and backing plate to meet this shoulder halfway through. I shaved the top part off the retaining clip as well as trimming down the spring. I finally got them to fit, but I can say I think any deeper offset and I'd have been screwed. They do tuck nicely under the fenders and ride sooo much better. Less truck lean, less noise. I'm pretty happy with them that's for sure. Did wheel bearings too, and replaced bearings and races on the left side. I'm happy with the way my new DD is shaping up and just thought I'd share. /forums/images/graemlins/cool.gif
     
  2. txbartman

    txbartman 1/2 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Do you have any issues now with contact with the frame rails or anything like that on full turn? That was a concern of mine with the 15/42s if I went with too much backspacing.
     
  3. laketex

    laketex 3/4 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    no i dont have any contact. However, these are only 35x12.50 on 15x8 rims. I am about 1/2" from the steering rod on the crossover.
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Hmm, I've got 4.25-inch backspacing on my 15x10 Cragar steel wheels and didn't have to remove hardly any metal from the calipers. The caliper brackets were the cause of most of my interference. /forums/images/graemlins/frown.gif But indeed, I do like the way it keeps my 35-inch BFG Muds tucked up under the fenders. /forums/images/graemlins/cool.gif But this was on an 8-lug Dana 44. I think a 60 needs a lot more work.
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Yeah the D60 caliper does take quite a bit more grinding. I found out I have 3 rims with 3 1/2" B.S. and one that is 4" when I ground mine. Ground one side and took some mental notes once it was done. Scored the other side exactly as far inboard as the first and ground a ton off...then tried to fit the rim. It wasn't even close. I kept grinding and finally thought to double check the B.S. on both fronts...sure enough i have one that is 1/2" deeper/forums/images/graemlins/crazy.gif

    Rene
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    You and Dan are doing my D60 too! Mine are 4 1/4 BS as well...my old ones were 4 1/8" and it was an 8 lug 10 bolt front and it took me three hours of grinding. I can't imagine how bad the '60 will be.
     
  7. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    It friggin SUCKED... At just about 9 something at night... and something like 3 hours behind you already... makes a guy wish he could just drive a friggin Yugo. Well... not really... but you get the idea! /forums/images/graemlins/grin.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/grin.gif

    End of story though... the new wheels look great on Bryan's truck, and really improved handling too! Now we need to get the rear springs replaced, and yank the 3" body lift outta there, and he'll be happier than a pig in... well you know. /forums/images/graemlins/thumb.gif

    -Dan
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    But the question is, when are you doing mine? And which one of you guys is big enough to help me wrestle that behemoth of an axle under my truck?
     
  9. MTBLAZER89

    MTBLAZER89 3/4 ton status GMOTM Winner

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    [cough]i think somebody wrote a tech article on this [/cough] It's Somewhere around here /forums/images/graemlins/pimp1.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Grr....I promised myself I wouldn't renew my membership until my truck ran...grrrrr.........
     
  11. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    [ QUOTE ]
    [cough]i think somebody wrote a tech article on this [/cough] It's Somewhere around here /forums/images/graemlins/pimp1.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif

    [/ QUOTE ]

    Problem being... that write up you did was on (what appears to be) a Dana 44... not a 60. I wish my damn camera was charged... Id run out there and take a few pics. Let me tell you this... the GROOVE in the caliper in its deepest place is probably 3/8"+ deep! /forums/images/graemlins/eek.gif

    Thanks for the pointer though! /forums/images/graemlins/thumb.gif

    -Dan
     
  12. laketex

    laketex 3/4 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    I'll bring a camera over wednesday....it's rough how deep that shoulder is....


    And Tim, that would be Dan, he's the HOSS of our twosome. Yall two have fun!!! Personally my hand is still stinging from holding the grinder for 3 hours!
     
  13. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Bryan... would you be so kind as to define "HOSS"???
     
  14. laketex

    laketex 3/4 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    sure. HOSS = BIG OL BOY.

    Now get your panties unwadded. /forums/images/graemlins/rotfl.gif
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Bad Dog not only did a write up on D60 caliper grinding but took some great pic's.

    http://www.coloradok5.com/d60calipergrind.shtml

    /forums/images/graemlins/thumb.gif

    Rene
     
  16. laketex

    laketex 3/4 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    thanks for saving me the time. Mine aren't that purty, but they work....
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    [ QUOTE ]
    And Tim, that would be Dan, he's the HOSS of our twosome. Yall two have fun!!! Personally my hand is still stinging from holding the grinder for 3 hours!

    [/ QUOTE ]

    Perfect! I bet it'll be NUMB when you're done with mine. See, I'm just helping you out.

    Dan's wife is complaining about truck stuff. That's never good...that's when it's break time.
     
  18. j20m715

    j20m715 1/2 ton status

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    Hey Bryan
    /forums/images/graemlins/thinking.gif My 16.5's fit just fine (read NO GRINDING). /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     
  19. HarryH3

    HarryH3 1 ton status Author

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    [ QUOTE ]
    My 16.5's fit just fine (read NO GRINDING).

    [/ QUOTE ]
    I sure hope you have some good bead locks! /forums/images/graemlins/shocked.gif I got rid of my 16.5's because the tires would literally fall off the wheels at 18 PSI. /forums/images/graemlins/angryfire.gif
     
  20. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: There\'s a LOT of difference between 3\" and 4\" backspacing!

    [ QUOTE ]
    I sure hope you have some good bead locks! /forums/images/graemlins/shocked.gif I got rid of my 16.5's because the tires would literally fall off the wheels at 18 PSI. /forums/images/graemlins/angryfire.gif

    [/ QUOTE ]

    I'm glad to see at least one other person agrees with me. My friend lost a 38" Swamper at 25 psi in deep mud!
     

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