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Last Post 25 Mar 2015 02:33 PM by  OZMDD
Clarification on strut bar mounting rules in STX
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ChristianNJ
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New Member
Posts:10


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22 Feb 2015 10:46 AM
    Hi,
    I am looking for some clarification on the strut bar rules in street touring. There are some strut bars available for the Golf V, which would need a minor cut out on the upper firewall to be properly mounted. In the rules below it says "This does not permit any modifica-tions to the frame or unibody beyond the allowed mounting holes." Does "mounting holes" just refer to holes for mounting bolts or also for holes for strut bar clearance? There is pretty much no way in installing a strut bar without minor fire wall modification.
    Any input would be appreciated.

    Regards
    Christian


    G. Strut bars per Section 12.18 are permitted with all types of suspension, subject to the following constraints:
    1. A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.
    2. A triangulated (3-point) strut bar may be removed, modified, or sub- stituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.
    3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2” (50.8mm) in any di- rection of the actual suspension attachment to the chassis.
    4. Except for standard parts, no connections to other components are permitted.
    Additional holes may be drilled for mounting bolts. Only “bolt-on” at- tachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifica- tions to the frame or unibody beyond the allowed mounting holes.
    Davidss
    Basic Member
    Basic Member
    Posts:181


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    27 Feb 2015 02:26 PM
    You can not modify the firewall.

    Luckily many autocrossers have tested strut bars and found them to have next to zero gain. So save the money and hassle and don't buy one.
    drdisque
    Basic Member
    Basic Member
    Posts:317


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    27 Feb 2015 04:01 PM
    And it makes sense particularly in this case - if the bar is so close to the firewall that it actually requires modifying it, then what is the point of further stiffening what is probably the stiffest point of the chassis?
    ChristianNJ
    New Member
    New Member
    Posts:10


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    27 Feb 2015 07:51 PM
    In the past I have seen some strong effects from braces, especially in between the control arms but in those days car chassis were a bit softer. I am running 160 N/mm springs (~900 lbs/inch) with upgraded bushings and 255/40-17 tires on 17x9 rims. I somehow feel it should feel more direct than it does and I wonder if I have too much chassis flex.
    I wonder if it also depends on what strut brace gets used. To me Wiechers braces are pretty much the ones to have:
    http://www.wiechers-sport.de/images/stories/virtuemart/product/511032.jpg
    Davidss
    Basic Member
    Basic Member
    Posts:181


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    01 Mar 2015 03:05 AM
    Running that large of a tire (255) on a 9 inch wheel is likely the cause of the lack of "direct" feel.

    Regardig the strut brace a lot of top drivers have scientifically tested them and all chosen not to run them. In addition to testing lap times another method I have used in the past to determine the efficacy of strut braces was to replace the pivot bolt in a strut brace such as the one you pictured with a soft wooden dowel. After taking a few runs/laps in the car you remove the dowel and check to see if there has been any markings or deformation of the wood.
    ChristianNJ
    New Member
    New Member
    Posts:10


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    01 Mar 2015 03:26 PM
    I like the idea of checking with something which actually "detects" if there is motion/flexing or not. In some other forums focussed on autocross in Europe the strut brace is still seen as something valuable. I am now interested to put this to rest in a test and tune session.
    I thought 255 on a 9 inch rim should not be too excessive. The thumb rule I was following says wheel width plus 1 inch as tire size. I am mildly over this. What would you run on a 9 inch rim? 245 max?
    sjfehr
    Advanced Member
    Advanced Member
    Posts:634


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    01 Mar 2015 06:15 PM
    255/40-17 is Porsche OEM size for 8.5x17" rims, and certainly not overtired; you can go to 265 if you wanted. Easy answer: find out what other people are running on your car and copy that.
    rodhx
    New Member
    New Member
    Posts:89


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    02 Mar 2015 07:43 AM
    I can't picture why a two-point bar would require firewall modifications.

    Folks run 255s on 9" wheels for many applications. Lots of e36 M3 guys, myself included, run that combo. I think its pretty common in STR as well.
    ChristianNJ
    New Member
    New Member
    Posts:10


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    02 Mar 2015 07:23 PM
    Please check pictures. Things look a bit different on the fifth generation VW Golf versus some other cars.
    Attachments
    rodhx
    New Member
    New Member
    Posts:89


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    02 Mar 2015 09:26 PM
    Thanks for the pics! Unfortunately I don't see how that could be legal in Street Touring.
    OZMDD
    Basic Member
    Basic Member
    Posts:131


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    25 Mar 2015 02:33 PM

    Just because lots of people run that combo doesn't mean it is a great combo for feel. I ran that combo for years on my STR car, and have found that the steering feel is much crisper on Whitener's setup.
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