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strut bar testing, methods, results?

Last post 05-20-2008, 8:32 PM by VW_rob_85. 7 replies.
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  •  05-08-2008, 10:38 AM 299081

    strut bar testing, methods, results?

    I'd like to test the strutbars i have for actual improvements, so explain some methods and results you've seen.

    I've got upper and lower front strutbars and an upper rear bar.

     

    Any tips on acquiring a skid pad area? 


    Rob P.

    04' VW pegl-leg GTI
  •  05-09-2008, 10:17 AM 299324 in reply to 299081

    Re: strut bar testing, methods, results?

    Nobody tests the effectiveness of their strutbars? 

    Rob P.

    04' VW pegl-leg GTI
  •  05-16-2008, 3:55 PM 300705 in reply to 299324

    Re: strut bar testing, methods, results?

    VW_rob_85:
    Nobody tests the effectiveness of their strutbars? 

     

    I got one off of EBay; my car now has 23.2more HP and has doubled it's MPG.Cool


    Erik B.
    Wisconsin Autocrossers, Inc
    www.waiautox.org ___/\___/\___/\___/\___/\___
    2007 Mazda6
    2000 "Fozda" ZX2 S/R--STS Anti-Civic
  •  05-17-2008, 2:31 AM 300780 in reply to 300705

    Re: strut bar testing, methods, results?

    http://www.tercelreference.com/project_development/rear_strut_bar/rear_strut_bar.html
    Rob P.

    04' VW pegl-leg GTI
  •  05-17-2008, 11:45 AM 300794 in reply to 299081

    Re: strut bar testing, methods, results?

    Here is another interesting take on strut bars: Stress Bar Theory

     I'm no engineer so I can't speak to the conclusions, but it seems logical to me. I'd love to hear some engineering types critique the analysis.
     


    '89 RX-7 GTU
    Speed in Gears Calculator
  •  05-20-2008, 6:25 PM 301329 in reply to 300794

    Re: strut bar testing, methods, results?

    Well, the geometry and force diagrams are all in order.  However, the real question is what will result from a 333 pound force being applied to the frame at the strut mount?  The author tells you how much camber change will result from a frame motion of 0.2 inches, but does not give any indication of how much frame motion is likely to occur.  It would also be interesting to see the strain gauge data that the author refers to in the second segment of the article.

    John S.
    S2000 #42as
  •  05-20-2008, 7:12 PM 301339 in reply to 301329

    Re: strut bar testing, methods, results?

    Here's what I've done to determine actual movement:

    1.  Make a pseudo STB using two pieces of tubing that slide togehter somewhat snugly.

    2.  Mount the STB normally.

    3.  Safely block the car from rolling, jack up one side of the car, place it on jack stands, and remove both wheels.

    4.  Using two high lift (18 to 24") floor jacks placed under the front and rear suspensions on the side of the car with the wheels removed, raise the car and remove the jack stands.

    5.  Lower the car to normal static ride height.

    6.  Carefully mark the overlap joint on the two tubes that make up the pseudo STB.

    7.  Carefully raise the car, maintaining the desired rake front to rear, until you see a 30 degree roll angle.  Place jackstand back under the car.

    8.  Carefully mark the overlap joint on the two tubes that make up the pseudo STB.

    9.  Put the wheels back on the car and put it back on the ground.

    10.  Remove the pseudo STB and measure the distance between the two marks.  That will give you a very rough idea of the deflection in the strut towers.  

     


    -----
    John Coffey
    http://www.betamotorsports.com
  •  05-20-2008, 8:32 PM 301352 in reply to 301339

    Re: strut bar testing, methods, results?

    Excellent implementation, that sounds pretty solid and it will vary between cars.  To add to that, if you want to know how much compression the towers feel per the author, you could use the same method:

     

    Take an oring and place it at the overlap joint(mark it first), then take some dips similar to AX courses/speeds(mark this), then take some progressively larger bumps and record as you desire. 

     

    Wouldn't this distance show the slop/possible camber change of the chassis during bumps?


    Rob P.

    04' VW pegl-leg GTI
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