Bent stiffener plate and poor handling

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by milleniaman, Jun 30, 2013.

  1. milleniaman

    milleniaman Junior Member

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    Hi Prius owners,

    I've had my 2005 (260,000 mi.) for 2 years and handling has always been a problem. I don't understand the meaning of the terms sway, twist, etc in reference to the prius frame so will just describe the problem.
    At highway speeds it's dangerous. It won't track well. It's aligned with new front struts and new tires. A sharp veer results in cyclic swerving back and forth and dipping as well. It takes several cycles to return to stability.
    I have read about the mods that can be made and today checked my stiffener plate. It's bent. See pic. Obviously this is the place to start.


    However, I have a chance to buy a better prius at a very good price so can't wait to analyze the situation and would like some expert advice from the members of the site as to whether this plate would account for the problem I am having.

    Thanks 20130630_141702.jpg

    John C.
     
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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  3. dorunron

    dorunron Senior Member

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    Just for reference and information purposes, what exactly is the size, brand, and series of the tires you are running now?
     
  4. milleniaman

    milleniaman Junior Member

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    Thanks Jimbo

    195/65/15 Dorunron
     
  5. dorunron

    dorunron Senior Member

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    Brand?, Series? Example Bridgestone Ecopia 422, Conti Pro Contact etc.
     
  6. milleniaman

    milleniaman Junior Member

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    Whoops!
    Hankook 727
     
  7. dorunron

    dorunron Senior Member

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    Thanks for the info, it is informative.
     
  8. Agent J

    Agent J Hypoliterian

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    So you bought this car used? was it ever involved in an accident? the chassis might have been compromised that's why the brace is bent and thus getting unstable behaviour as the geometry of the 4 wheels are already not in line any more. if the chassis is misaligned, buying an aftermarket brace wouldn't probably fit.

    If the brace was bent because something hit it, then it's probably fine to replace it unless the mounts got misaligned as well.
     
  9. milleniaman

    milleniaman Junior Member

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    The plate recommended by Jimbo arrives today and I will install it ASAP

    The dent is vertical so seems to have resulted from road conditions and less likely the result of body damage

    Wish me luck.

    John C
     
  10. milleniaman

    milleniaman Junior Member

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    The plate is on. The ride is significantly improved. It tracked down the interstate much easier with less strain on the driver. Cornering at low speeds is neutral as opposed to under steer before. All in all I'd say it's close to stock performance. The handling problems have been reduced by around half Swerve oscillation amplitude and cycles are down to half. But if a deer jumps in front of me I can easily imagine losing control still.

    I can't understand how the improvement was achieved technically but I'll take it!



    N80IPS ? 2
     
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  11. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The center hump can act like a hinge in the floor of the car. The stock strap prevents bending in tension, while the aluminum plate also resists bending in compression. Once bent, your strap was not resisting either form of bending. Your car was changing shape as you drove.

    [​IMG]
     
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  12. Mike500

    Mike500 Senior Member

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    Skeptics, who NEVER tried them, poo-poo chassis stiffeners.

    When I got my Prius, I felt the same way.

    I started making them and NEVER looked back.

    The plate is GOOD start. Even better is my box beam, which has the ultimate stiffness.

    Apparently, maintaining separation between the frame rails makes a big difference.

    I have uploaded several photos of my design.
     

    Attached Files:

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  13. milleniaman

    milleniaman Junior Member

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    That seems to about describe what I was experiencing. I appreciate everyone's comments on this topic. This car is still viable so I don't have to shop for a new one just yet though the other has 100k miles fewer and is real nice (04 model top of the line for $4500).

    Thanks
    John

    N90 DUAL CORE2 CZ ? 2
     
  14. Daves09prius

    Daves09prius Active Member

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    Don't stop with just the G7 rear tunnel brace. I'd also get a front strut tower brace from eBay and a new rear sway bar. Your prius will handle much better with those simple bolt on mods.
     
  15. N3FOL

    N3FOL Member

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    Sounds like the body frame is bent as described.
     
  16. milleniaman

    milleniaman Junior Member

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    Thanks for the recommendations. I could use better handling still.

    Body frame damage? In addition to the plate?



    N90 DUAL CORE2 CZ ? 2
     
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