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V8 Front Sway Bar

Discussion in 'VN - VP Holden Commodore (1988 - 1993)' started by VN Commy, Jul 30, 2006.

  1. VN Commy

    VN Commy New Member

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    Is the front sway bar from the V8 stiffer than that of the V6? Will it also fit straight on to a V6 VN? I might have an opportunity to pick one up for cheap this week and I want my car to sit a little bit flatter in the corners.
    Cheers.
     
  2. HATER VP

    HATER VP Guest

    Theres about 4 different sway bars. A standard V6 sedan its the same for a standard V8 sedan, and even with FE2, but from a car with IRS. But is different with the V5W suspension. If you got FE2 then you will need one out of a FE2, Without IRS, these have a different ID code. The codes all start wit C, and have another letter after it. If you got standard suspension you will need one with the code CH.
     
  3. pandaman

    pandaman Aussie Muscle Fan

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    The V8's had a thicker swaybar at the front. I've been told it will fit, You'll probably need the mounting brackets and rubbers. Also, might as well fit a new link pin kit while you're at it. The other dude is right that there were 4 different sized swaybars, but I'm pretty sure the front ones are all interchangeable, and I'm certain that the V8 swaybar was bigger than the V6. Also, no VN had IRS so why would that be an issue HATER VP? hell, why would it make the front swaybar different anyway?
     
  4. HATER VP

    HATER VP Guest

    Sorry guys I was refering to VP. I dunno why but it must be for a reason.
    V8-FE2 compared to FE2 with IRS is only 1mm.
    The different bars are 22, 25 & 26.
    The V6 FE2 is the same size as the V8 FE2 but have different id's
     
  5. mouce

    mouce Physics Geek

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    If you really want to make it a lot stiffer, I think there's a way to do without the link pin all together. And the sway bar just bolts straight onto the control arm. Makes the ride firm as hell.

    I think that was the setup used on the VK and VL. I think there is a conversion kit available for the VN. Maybe it's whiteline that have got it. Do a bit of digging...I know it's out there, I've seen it done before...can't remember where though.
     
  6. VN Commy

    VN Commy New Member

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    I just got the V8 sway bar and compared it to the one allready in the car. It doesn't seem to be any thicker...
    I'll investigate doing without the link pin though.
     
  7. greenfoam

    greenfoam New Member

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    FE2 V8 is definatly thicker than stock V6, because I bought new rubbers not long ago:) but I'm not sure on it vs V6 FE2 and stock V8. I'd say the group A had a different a sway bar because it had different springs (not FE2) I forget the option code for them but you can't buy them anymore anyway so it doesn't matter :)
     
  8. greenfoam

    greenfoam New Member

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    The early models had a smaller pin that bolts to the control arm instead of the strut, the hole to mount it is still there on the VN
     
  9. VN Commy

    VN Commy New Member

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    I've just got a non FE2 V6 and I think the sway bar came from a non FE2 V8.
    I'll put it on and see if it makes a difference.

    If thats the case then I mite go to the wreckers and see if I can get a couple of these smaller pins from a VL or something. Anyone know if there's a similar setup for the rear sway bar?
     
  10. Cheap6

    Cheap6 New Member

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    VP V6 sedan, live axle: F:27mm (prob. VN too)
    VL-VR sedan, live axle: R:19mm
    VB-VK sedan, (live axle): R:12mm

    I have a vague recollection that ALL VN V8 were/are FE2.

    A 1mm difference in 'bar dia. is significant.

    Theory:

    For a bar in torsion, angular deflection is:

    theta = TxL/(GxJ)

    where:
    theta is angular deflection (twist)
    T = torque applied (twisting force; force x distance at which it is applied)
    L = bar length
    G = Young's modulus ("spring" stiffness for the material. Steels are around 200GPa)
    J = moment of inertia of cross sectional area of bar (a function of shape/size)

    For an ARB, G = a material property, so doesn't change with size, and L is fixed by the suspension designer, so the relationship between T and theta is determined by 'J' which is a function of the fourth power of dia. for a circular cross section. The 'arms' of the bar will bend too but not so much as the deflection due to twist and that is also a (different) fourth power function anway.

    Reverting to the VB-VL style front links and 'bar may (will?) change the lever arm length and hence the 'bar stiffness, by altering T and if it is shorter (I think it is), L. It will also add inner lower control arm bush deflections to the 'bar deflection, which was the reason for moving the 'bar links in the first place. Custom links (using steering rack tie rods :)) was a quite common pre-VN aftermarket mod. to increase ARB response/stiffness.

    Practice:

    A 20mm 'bar is (20^4)/(19^4) = 1.23 times stiffer than a 19mm 'bar. Note that this is just the 'bar stiffness. Spring stiffness and that due to roll centre height/track width needs to be added to determine total roll stiffness. A stiffer rear bar will increase oversteer, a stiffer front bar may increase understeer but is complicated by altering suspension travel, hence geometry. (A live axle car doesn't have the quite the same geometry effects at the rear).
     
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  11. pandaman

    pandaman Aussie Muscle Fan

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    False. The rest of that post was great though, you should write a textbook on mechanics of materials, I guarantee you'd do a better job than the fella who wrote the one I had to use.
     
  12. VN Commy

    VN Commy New Member

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    Haha yea I was thinking about the textbooks I had/have to use. Thanks Cheap6. I'm pretty sure the sway bar came from a V8 executive so I dono about the FE2. I still havn't got a chance to put it on though cos I've been helping my mate pull the engine out of his alpha romeo. :bang: (I'm glad I have a holden)

    I had a quick look under the car and it looks like the previous owner has allready done the link conversion because it allready has a short pin going to the controll arm.
     
  13. Cheap6

    Cheap6 New Member

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    I wasn't sure re. VN V8. I would have an old mag. from when the VN V8 was released but it is in storage so can't access easily. I'll check when I get the chance.
     

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