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grinding the 60, for 15''rim, 4.25 vs. 4.50 backspacing question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 1990K5, May 14, 2002.

  1. 1990K5

    1990K5 1/2 ton status

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    grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    obviously the 60 has to be ground quite a bit for 15" rims to fit. but does it make much difference to get 4.50 backspacing vs.4.25 rims? what backspacing are all you guys rinning? i need to order my wheels tommarow. thx--j.c.
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    I'm running 4.125 to be exact. In any case .250 shouldn't make much difference as far as grinding goes. Only thing I would be concerned about (that I can think of) is the extra material removed from the retaining slide.
     
  3. m j

    m j 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    the correct BSing depends on tire diameter
    I think the trick is to get as close to zero scrub radius as possible.
    that is centre of the tire contact patch at the intersection of the SAI and the ground.
    taller tire would need less backspacing to achieve this then a short tire
    would be nice to see a discussion of scrub radius results
     
  4. topless1tonk5

    topless1tonk5 Registered Member

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    ya i understand the center of the rim (in a perfect world) should be centered with the spindle pivot point. but i am asking from a grinding stand point? like how many jack and cokes is required for the job?
     
  5. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    I just got a set of 15x10 wheels to go on my truck. With 3 inches of backspacing I only had to clean up casting flash to get them to clear my D60. Some people don't like the big offset but I prefer it over grinding the crap out of my calipers!
     
  6. Triaged

    Triaged 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    I have heard of D60 calipers breaking in half from having so much ground off! I have 3.5" BS on my 15x10's and had to do hardly any grinding at all. I removed like 1/16" from my D44 calipers. I would never run 4.5" of BS on my truck! Aside from having to grind the caliper ALOT you might have tie rod clearance issues. Factory wheels had like 3-5/8" BS...I don't see why you need more. If you want the truck to be narrower use 8" wheels or 16/16.5" wheels and as much BS as you want.
     
  7. four_by_ken

    four_by_ken 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    I have also "heard" of the calipers breaking. But, I have never seen it or heard from the person it happened too. For that to happen to a Dana 60 caliper... someone must have shaved the hell out of it.

    Ken H.
     
  8. topless1tonk5

    topless1tonk5 Registered Member

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    where are you guys getting these rims with these different offsets? i measure it by laying the rim face up on a flat surface and measureing from the flat surface up to the lug hole or wms right? thx---j.c.
     
  9. topless1tonk5

    topless1tonk5 Registered Member

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    so a 3'' offset would put the wheel out further than a 4.25 off set right. what is the disadvantage of more offset other than harder on steering components. would'nt it give you more stability?
     
  10. BIGJ

    BIGJ 1/2 ton status Author

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    You'll have to grind about <a target="_blank" href=http://www.pirate4x4.com/forum/showthread.php?s=db1874dcae1b2ba5d49bf59cf44e42f0&amp;threadid=53053>this much</a> for a wheel with lots of backspacing.

    Seems like a lot of work to me.

    BIGJ
     
  11. Triaged

    Triaged 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    Yes...less BS moves the wheels out farther. It gives you more stability but can cause higher steering effort and makes you have to trim more to get the tires to not rub.
     
  12. 79Beast

    79Beast 1/2 ton status

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    I hate to tell you this, but call FourWheelParts and buy some steel rockcrawlers with 2 1/2" backspacing. They will clear your D60 calipers with only SLIGHT grinding. I do not recommend trying to grind off enough to run 4-4 1/2" backspacing. I think it would be dangerous to grind that much off of the caliper. If you do a search, 72THING posted the PN for 8 lug 15x10's with 2 1/2" backspacing. It was either here or the ORD forum.
     
  13. topless1tonk5

    topless1tonk5 Registered Member

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    Re: grinding the 60, for 15\'\'rim, 4.25 vs. 4.50 backspacing question

    i just ordered the black rockcrawlers from 4wpw yesterday with 2.75 backspacing. 45 ea.
     

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