Rear sway bar pivot area binding

Discussion in 'Suspension, Brakes & Chassis' started by Performance nut, Apr 17, 2019.

  1. Performance nut

    Performance nut Well-Known Member

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    I was talking with some folks in this thread about induced oversteer when I installed a BMR rear brace. No one felt that the brace should have induced oversteer; however, I can tell you that it did so much that I had to make adjustments to my suspension to get it back to neutral. Nothing else has changed. Current theory is the rear sway bar is binding at the pivot point.

    Had the car on a drive on lift and the sway bars were disconnected from the end links, neither one moved. Loosened up the bracket to allow the sway bars to pivot which they did but as soon as the brackets are tightened, they stopped moving. I currently have the GT350R sway bars installed.

    Are these supposed to bind? Doesn't seem to be an obvious way to loosen these up if they are supposed to be loose in the bushings.
     
  2. Grimace427

    Grimace427 Well-Known Member

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    Rubber bushings or poly? Are the bushings lubed?
     
  3. OP
    OP
    Performance nut

    Performance nut Well-Known Member

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    Rubber (Ford bushings) and yes they are lubed.
     
  4. OP
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    Performance nut

    Performance nut Well-Known Member

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    Quick update, it may have been the intention from Ford to make these deliberately tight to increase effectiveness. Do more with less. Researched this as well as spoke with some experts. This is different than what the aftermarket bars as they do not bind.

    What has me curious now is how the effective rates change when you have a physically thicker bar that sort of floats versus a bound, immovable bar that is slightly smaller. And on top of that, how modifications effect each like when you remove rubber bushings and install parts that do not deflect as much.
     
  5. BmacIL

    BmacIL Enginerd

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    Short answer: No, and this is where I believe some of your oversteer issue is coming from.

    I'd honestly try to drill them out such that the bar doesn't have room to freely deflect, but also can be rotated with fairly minimal effort (maybe 5 or so lbs of force at the link attachment).
     
  6. Grimace427

    Grimace427 Well-Known Member

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    I'm having trouble understanding the issue. Is it that the bar(when mounted at the bushings but no end links) does not move at all when you grab from the end of the bar or is it just under noticeable tension? If it is the first there is definitely a problem likely being the mounts are too small for the bar. If it is the latter then I would say that is normal for an OEM bar in rubber mounts. Aftermarket swaybars in poly mounts will move freely with little to no tension. OEM bars of any manufacturer will have very little movement when mounted.
     
  7. NightmareMoon

    NightmareMoon Well-Known Member

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    The rear bar is really pretty lightweight part with short lever arms. I would not be very hard to keep enough tension on it to stop it from drooping on it's own.

    In my car the rear bar won't droop in the bindings if disconnected, but it doesn't take much pressure to get it to move. What little binding there is would be insignificant compared to the 3700lbs of car.

    The front PP bar OTOH is completely 'bound' in the bushings and locked in place. That's where I've heard the Ford engineers wanted to get some extra on-center feel from bushing binding, not the rear bar. And FWIW, I didn't notice any loss of feel when going to an aftermarket front bar (albeit stiffer) with poly bushings and much less bushing bind.
     
  8. Radiation Joe

    Radiation Joe Well-Known Member

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    #8 Radiation Joe, Apr 19, 2019
    Last edited: Apr 19, 2019
    I am surprised this hasn't been discussed earlier. I just installed the Steeda subframe support kit. My car now oversteers like crazy. I thought I'd messed something up, but then I thought about what this kit does and how the rear bar is mounted.
    First, the kit essentially eliminates vertical movement of the rear sub-frame. The bar is mounted to the rear sub-frame. Before installation, when the car leaned, the sub-frame could move, making the rear bar less effective. Once the kit was installed, the sub-frame was essentially locked, making the rear bar much more effective. Any of the sub-frame lock out kits will have this same effect. I believe this is what you are experiencing.
    [edit] Sorry, didn't realize you had CB010 prior to install of the brace. I still think the lock-outs tend to increase oversteer for the reasons I mentioned.
     
  9. Norm Peterson

    Norm Peterson corner barstool sitter

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    I agree - as long as stiffening up the connection between the subframe and main chassis structure has resulted in reducing the amount of relative roll between the two. Rear roll resistance "lost" through OE bushing compliance in roll effectively moves the TLLTD forward. Recovering it by any means obviously moves TLLTD rearward relative to OE, which is clearly an oversteerish effect.


    Norm
     
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