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Why are the rear axle housings narrower ?

Discussion in 'The Garage' started by MOLON LABE, Nov 2, 2005.

  1. MOLON LABE

    MOLON LABE Registered Member

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    Why are the rear axle housings narrower than the fronts ? Or is it that the fronts are wider ?
    I see there are spacers available to correct this, is this for looks only or is there another benefit ?
     
  2. Boondocks

    Boondocks 1/2 ton status

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    Quite a while back, I watched a program that stated there is better stability with the front track slightly wider than the rear track.

    Do know if it is true, and if so, to what degree.
     
  3. cbbr

    cbbr 1 ton status GMOTM Winner

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    IIRC it helps the turn radius.
     
  4. sweetk30

    sweetk30 professional hooker Premium Member

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    exactly correct. the truck will turn in a smaller circle this way.
     
  5. sunnyc123abc

    sunnyc123abc 1/2 ton status

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    i always wondered that too... now it makes sense
     
  6. muddyblzr

    muddyblzr 1/2 ton status

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    another reason for the front being wider might be that it has alot more weight to hold. wider means more stable. that and turning raduis seem to make the most sense.
     
  7. 6.2puller

    6.2puller 1/2 ton status

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    Yah its for turning radius, thats why it really cracks me up when you see wheelers who want a tighter turning radius will got out of their way to widen out their rear axles to "fix" the "problem" the factory apparantly never noticed :haha:
     
  8. JanneB

    JanneB Registered Member Premium Member

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    :confused: Ok I am stupid but please explaine how it makes the turning radius smaller. I just do not get it?
     
  9. stano

    stano 1/2 ton status

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    I not sure, but is it because the front is made by spicer and the rear by GM
     
  10. Mudgod

    Mudgod Registered Member

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    Tracking, the outside wheel doesn't have to travle as far. Take a compass and draw a circle. Then open it up a little. The larger circle will have area in it.
     
  11. CHEVY 4WD

    CHEVY 4WD 1/2 ton status

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    I have 1" spacers on the rear beause I have a 14bolt and wanted to stay 6lug. My truck dident track or turn any better before or after, It looks a lot better IMO and does cover my bedsides with alot more mud
     
  12. SUPER'BURB

    SUPER'BURB 1/2 ton status

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    Whats up with my weirdo set up :confused: ?
    When I changed from 12 bolt to 14bff my width became the same.
    I thought it was just a 1/2 ton thing.
    Or did I get a hold of a super special full width 14bff for $100????
     
  13. muddyblzr

    muddyblzr 1/2 ton status

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    sounds like you got a van width, there about 3'' wider overall.
     
  14. Greg72

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

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    I run rear wheel spacers on a conventional 14BFF, and the ORD Highsteer arms on a front D60. My turning radius is INSANELY good....I didn't pull out or mess with those steering stop bolts either. My wheels are a standard 3.75" BS Wagon Wheel...so no real magic there. I never figured out what my actual scrub radius is, but I can make U-turns into the "inner" lane as I go around the divider at the stoplight.

    Pretty impressive for such a large vehicle.


    :usaflag:
     
  15. Blue85

    Blue85 Troll Premium Member

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    Well a K5 has inherently good turning radius because of the short wheelbase. Of course, they put the same rear ends in Subs and extended cabs, which are probably the vehicles they were actually worried about.
     
  16. 84k5

    84k5 1/2 ton status

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    It makes it easier to clear cones when rock racing.;)
     
  17. Leper

    Leper 1/2 ton status

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    think of a backwards tricycle
     
  18. BigCountryx

    BigCountryx 1/2 ton status

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    [​IMG]
    So what's your point?
     
  19. marv_springer

    marv_springer 1/2 ton status

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    Sorry to "but-in".... but I was discussing this w/ colbystephens on another thread....

    Just so I understand, are you saying that a more narrow track rear axle allows a tighter turning radius?

    I can't agree w/ this.... Please educate me.

    Here's a diagram showing a theoretical turning radius.
    [​IMG]
    I can't see how the width of the rear axle would affect it.

    Marv
     
  20. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Your picture makes sense, but it does not account for friction and drive motion vectors (not sure if that is the correct term though)

    I think it has to do with rear tire scrub and leverage. The rear axle is a fixed unit (i.e. the rear wheels track one direction...front to back). If they were mounted on casters and the front wheels were driving the vehicle, it wouldn't matter how wide the rear axle was because the front wheels would travel in there natural path and the rear would follow. Because the rear axles drive the vehicle forward and have to travel a wider arch with a wider axle there is more resistance and leverage of forward motion. I didn't believe it at first, but have seen it demonstrated with r/c vehicles. (same chassis, front end, etc., but swapped in different rear ends with the same gearing and tires size, just different widths). One thing I saw is that it took a noticeable difference in width to change the amount of turning radius, so a few inches on a real life vehicle wouldn't seem to make much sense, but someone hypothesized that it had to do with the difference in weight (the vehicle was scale size, but not scale weight) allowing the tires to slip more.


    This is by NO means a scientific test, but I did see it with my own eyes. It does oddly make sense that as the wheels move toward the center of the vehicle that they would push the vehicle in the intended arch of the front wheels, but the furthur out they became they would leverage against the turning motion of the front wheels.

    I would ASSume it's much like pushing a shopping cart. If you push it forward then turn slightly the cart will turn. If you push in the middle it will continue to turn a short while until it straightens out. If you push on the outside of one of the handles the cart will tend to turn to the opposite side. The furthur out to one side of the handle you push the quicker it will turn the other way. I'm assuming a wider rear tire acts the same way. When taking a left turn, the left rear tire is trying to keep the cart straight (more pronounced with a locker/limited slip). The furthur out the wheel is, the more it fights the turning effort of the front wheel.

    Ideally (for turning), the rear wheel(s) would be dead center, but then you would lose stability (plus it would be an engineering nightmare for a rear wheel (4WD) vehicle). I'm ASSuming the engineers figured a slightly narrower rear (even if marginably smaller) would yeild a slightly better turning radius without giving up much stability.

    In a vehicle that is going to be seeing heavy loads (i.e. dually pickup or cargo van), they were more concerned with safety/stability than parking lot turning radius therefore a wider rear end.

    Maybe somebody who know a heck of alot more than I, can chime in and prove/disprove this theory.

    AGAIN, I AM NO EXPERT ON THE SUBJECT, SO TAKE WHAT I SAY AND HAVE SEEN WITH A GRAIN OF SALT...
     

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