Motorsport harnesss installs - forum info compilation / FAQ

Discussion in 'Track Prep & Tech' started by A.N. Other, May 17, 2009.

  1. A.N. Other Banned after significant club disruption Dec 5th 2

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    .
    Similar to the Roll cage installation guide, this draws together various information on installing race harnesses, some of which is already spread around the forum.

    If your car is "just" a track car... you may not actually know if you'll use it in competition, but this should help with installations.


    Firstly...

    Some of this thread is the work of others
    - who have either posted pics, or discussed the topics on the forum over the years :thumbup:


    Thanks to jamesa2, altern8, pascal77uk, fthaimike, pol, sambo, NigeP + various others



    This information is all given in good faith and is believed correct at the time of writing.

    Hope useful :)
     
  2. A.N. Other Banned after significant club disruption Dec 5th 2

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    1) MSA requirements:

    • Racing requires FIA homologated safety harnesses. Must be 'in date'. The expiry date stitched onto a label on the harness is the last date the harness can be used in MSA / FIA regulated competition
      • FIA Appendix J - Art. 253 states that "one anchorage point for two straps [is] prohibited for shoulder straps." Since the MSA refers to the FIA for racing, 3-point harnesses aren't allowed for UK racing.
    • Sprinting / hillclimbing requires:
      • 3 point safety harnesses for Road-Going Production and Road-Going Specialist cars
      • 4-point safety harnesses for Modified Production ('Mod Prod')
      • 6-point for Hill Climb Super Sports Cars, Sports Libre and Racing Cars
        (all as defined in the MSA Blue Book)
      • ... but does not appear to specify FIA Homologation (please shout if you know this not to be the case)
    • Rallying requires FIA Homologated 4 point safety harnesses (minimum)
    • Rallycross and Autocross requires 3 or 4 point safety harnesses (minimum) but does not appear to specify FIA Homologation (please shout if you know this not to be the case).

    However, the MSA encourages FIA-compliant harnesses:

    2) Trackday harness requirements:

    • Subject to any event officials checking cars, eg whilst noise testing, none :o

    Rough guide to types of harness in existence:

    • EEC Approved
    • Latch closing mechanisms
    • Turn buckle release mechanisms
    • Push button release mechanisms
    • FIA approved harnesses

    Also, design differences:

    • 2 inch straps, 3 inch straps, or 3 inch shoulder and 2 inch lap
    • Clip on harness straps, designed to fit over eye bolts
    • Non-clip on harness straps, which are 'permanent' fixtures
    • 3-point, 4 point, 5 point and 6 point harnesses

    FIA harness installation:

    FIAHarnessv2.JPG

    Note that Willans' version differs:

    Willansharnessdiag.JPG

    Main differences:

    • FIA states shoulder harnesses must sit in range of 10 degrees above horizontal to 45 degrees below
      - Willans says horizontal to 20 degrees below
    This is because:

    - Willans do not know which seat you are using....

    • FIA states crotch strap to be vertically downwards with 10 degree variation each way
      - Willans shows the mounting to the rear of the driver

    You'd always fall back on the FIA ones in competition, but make appropriate judgements within the variations shown.


    Actual install:

    IMG_1125.jpg
    (pic courtesy of sambo)


    Anchorage points - general


    The majority of harness installs will require some eyebolts like these:

    eye_bolt.JPG

    (source them from Demon Tweeks and similar)

    And some backplates like these:

    Eyeboltplate.jpg

    (source them from Demon Tweeks and similar)



    Lining up eye bolts

    • All eye bolts should be lined up so that the harness is not trying to twist the head under tension.

    Eyeboltsinline.JPG
    (Willans harnesses pic)

    ^^ Harnesses using clip on fittings over eye bolts have a small hole drilled into the securing clip.

    • Split pins can be fitted into the hook bracket to stop to stop any risk of them becoming unclipped.
    • It would usually take another object in the rear footwell to dislodge one, but as a lot of us on CGTI have track cars, driven to and from events with equipment inside, it's not impossible.


    FIA anchoring diagrams

    FIA253-43-1.JPG


    Setting eye bolts

    FIA253-43-2.JPG

    • Eye bolt orientation is adjusted with washers

    Eyeboltspacing.JPG
    ^^ Note the backplate is on the far side of the metal surface which the eye bolt is mounted through.
    (Willans harnesses pic)


    Tying off harness belt tails

    All harness tails should be looped like so:

    Beltloops.JPG
    (Willans harnesses pic)

    .... but some tails are double-stitched over, and even if undone. will not fit through again. Just try to do it :thumbup:


    Often rolled and neatly cable tied like this to stop the tails flapping around - just neatness:

    IMG_8565.JPG


    Shoulder harness anchor points:


    Options:

    1. Use roll cage anchor points
      • Take care if adding bars to a cage if you intend to compete with it:
        • the FIA specify a minimum tube spec of 38mm x 2.5mm, or 40 x 2mm
          (min tensile strength of 350 N/mm2)
        • but this does not conform with the MSA uncertified minimum of 45mm x 2.5mm or 50mm x 2.0mm
        • therefore you can install harness bars to MSA or FIA spec, but:
          • a non-FIA homologated cage built to MSA minimum spec (45mm x 2.5mm or 50mm x 2.0mm) can have harness bars added, and still be used in MSA competition.
          • a cage otherwise MSA compliant cannot be used with FIA spec harness tubes (tubes are too small), therefore can't be used in any UK competition.
          • an FIA compliant cage, where modified, will lose its status and be invalid for FIA or MSA competition.
      .
    2. Use existing or new fixing points on the car body

    -----------------------------------------------------------------------------------------------------​


    1a) Roll cage harness bars:

    liveNloud__59_.jpg

    (pic courtesy of pol)

    Note: harness bars must be used if using a HANS device


    1b) Wrap round rear cage lateral brace:

    plumb001.JPG
    (pic courtesy of pascal77uk)


    1c) Clip on rear cage lateral brace

    Mk1rearview.JPG
    Harnessbar3.JPG

    (pics courtesy of jamesa2)

    The welded insert is done to FIA spec:

    FIA253-67.JPG



    2) Car body fixing points: rear seatbelt lower mounting points:

    This is just within the permissable 45 degrees below horizontal, specfied by the MSA / FIA.

    Dubvelopments6.JPG
    (pic courtesy of fthaimike)


    Crossing shoulder harnesses

    There is much talk of the compulsory criss-crossing of shoulder harnesses for harness straps which exceed a given length: I can't find a reference to this anywhere.

    I have seen mention of harness straps longer than 70cm or longer than 25-30cm, but nothing I can find from the FIA or MSA backs it up.

    UPDATE - see jamesa2's posts 5 and 7 below.

    IMG_8528.JPG

    The only reference available is this FIA diagram shown earlier which talks in terms of a maximum 20 degree variation from the centreline:

    FIAHarness-253v2.JPG
     
  3. A.N. Other Banned after significant club disruption Dec 5th 2

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    Anchorage points - lapbelts:

    • is it ok to just weld these straight to the tunnel inside the car?
    Ans: No, put them on the other side of the metal you're attaching through. No requirement to weld on, and it spreads load, like so:

    Tunneleyebolt.JPG
    (pic courtesy of jamesa2)



    Anchorage points: crotch straps:

    (images are thumbnail clickable)

    Various options available:

    1) First on a restored Prodrive Subaru Legacy, with what is likely to be a 3mm plate welded to the underside of the floor. Quite a large area, which is key.

    IMG_8509.JPG IMG_8515.JPG

    2) This one is attached to the front seat rail:

    IMG_8523.JPG

    3) And this one is on the rear seat rail:

    IMG_8550.JPG

    Note the harness tails should be looped back under the harness buckle, like so:

    Beltloops.JPG

    .... but some tails are double-stitched over, and even if undone. will not fit through again. Just try to do it :thumbup:

    So there are a variety of options which people use. All of those are off pukka cars, pictures taken at the Autosport show.



    The latter two pics conflict with:

    ... but from various competitors it seems that the crotch belts seem to have a degree of flexibility with scrutineers.


    The third pic also doesn't comply with the angles shown on this FIA diagram:

    FIAHarnesscrotchmarkedv2.JPG

    ... but from talking to various competitors, crotch strap mounting angles seem to have a degree of flexibility with scrutineers.

    Then again, the FIA information is described as a typical safety belt installation....



    Where do harness installs go wrong?
    • Use of poor anchorage points.
    • Angles of shoulder harness straps directed straight to floor or too high
    • Crotch strap bolted through non-structural tin floorpan
    • Shoulder straps being looped around a piddly rear strut brace, which is far from structural.
    • eBay specials being acquired, possibly out of crashed race cars. They stretch and don't return to normal, so know what you're buying.


    Fails:


    • Harnesses rise above 10 degrees from the horizontal.

    • Levering around cage tube:

    Rcar10.JPG

    • Putting harnesses around rear strut braces, which are not welded between the backstays of a cage structure
      • like these, whether CDS, T45, allly or non-seamless thin diameter steel

    FMSBREVO.jpg

    • Aluminium tube is not safe (all alloy cages are banned in motorsport, so it won't ever be permitted)
    • There is a very fine line between welding a piece of CDS tube between the turrets, using 3mm back plates, and that same piece of CDS tube being regarded as part of a cage structure which shares the same 3mm backplates as backstay cage tubes anchoring on it. On the wrong day, with the wrong scrutineer the independent tube may not be regarded as part of the cage structure, so will fail this test:
    FAQs:

    (questions asked on the thread will be updated here)




    Reference sources:

    • FIA International Sporting Code - link
    • MSA Blue Book
    • Willians harness instructions

    Please comment

    If you do see anything that conflicts with your understanding, please post your views or experience, to help refine the thread (whilst keeping it on topic).

    If this post is copied to other forums, be good and credit www.ClubGTI.com - thanks :)
     
  4. James_mk2 Forum Member

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    Cheers for compiling all this Chris, really useful thread :thumbup:
     
  5. jamesa Forum Junkie

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    Thanks Chris :thumbup:

    INFO:

    Crossing shoulder harnesses:

    pp Willans

    Something I need to do myself ... [:$]
     
    Last edited: May 18, 2009
  6. Switch7

    Switch7 Forum Member

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    great write up and saved a lot of hasstle. ta for the pics as well
     
  7. jamesa Forum Junkie

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    Crossing shoulder straps

    Update:

    Borrowed from another forum

    Crossing shoulder harnesses:

    Regarding crossing the shoulder straps, IIRC I've only seen Schroth recommend it, and then only when the straps are more than a certain distance behind the seat. Again, IIRC the reason being if the shoulder straps are too long and not crossed, your shoulders can come out from between the belts as they stretch with the impact. With the belts crossed the change in the angle of force in the belts pulls inwards to stop that.
     
  8. A.N. Other Banned after significant club disruption Dec 5th 2

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    Great, thanks Andrew - I'll put an ammendment in to point to your two posts for now :thumbup:
     
  9. bigmac Forum Member

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    A lot of useful info their chris .....well done
     
  10. James_mk2 Forum Member

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    Don't know if this pic is of any use re. the harness tails?
    Seat006.jpg

    Also where is it possible to get split-pins for securing the catch on a willans harness?
     
  11. vrbanana Forum Junkie

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    A friends just been on the MOT refresher course and there is some info on harnesses that are fitted in place of, or in tandem with the original belt. The harness must have a British kite mark irrespective of any other tags such as an FIA tag. If a harness is fitted along side an original belt, then they must both comply, not just a cast of the original belt needing to comply.

    Once again though, it will be ultimately up to the tester
     
  12. jamesa Forum Junkie

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    Halfords / Trailer - Equine stores

    Great to see someone asking :thumbup: have not seen many fitted even on top class rally cars [:s]

    Belts - look up the video demo on here:

    http://english.schroth.com/tuning/
     
  13. James_mk2 Forum Member

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  14. fthaimike Forum Addict

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    Can someone tell me if it is safe to drill in the yellow area here (top, middle or bottom) & what is usually in that area to enable me to put my harness eyelet bolt through to meet a nut plate held in the tunnel? I want to use some of the seat rail end plating for added strength.

    Photo-0391b.jpg

    The Mk1 factory seatbelt ones for the other side that i will put the 2nd eyelet bolt into can be seen red circled so want to try to line up with these if possible.

    opinions?

    Ones i have here (yep bolt threaded on wrong side in pic):

    Photo-0792s.JPG
     
    Last edited: Mar 16, 2010
  15. A.N. Other Banned after significant club disruption Dec 5th 2

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    Moved to the harness thread :)

    On the outer sill, obviously you want to use the existing thread if you can. Ensure the eye bolt has a proper seating and is not sitting on an uneven surface.

    On the inner mount (tunnel), see post 3. Move it back a tad, and put the backplate on the underside of the tunnel.
     
  16. fthaimike Forum Addict

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    Cheers Chris i searched for the thread lol, just wondering if it was better for me to also drill through the spare space on the stronger welded in end plate and it would only be about 1-2cm at the most difference to the outer one but in a stronger area on the tunnel, also wondering if there was anything close in the marked section.
     
  17. A.N. Other Banned after significant club disruption Dec 5th 2

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    No need - just the backplate reqd. Note that the tunnel is double skinned - look underneath the car to check which bit is/isn't & drill the right part.
     
  18. fthaimike Forum Addict

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    you use the single or double area sorry?
     
  19. A.N. Other Banned after significant club disruption Dec 5th 2

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    What's going to be strongest? ;)
     
  20. pascal77uk Paid Member Paid Member

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    Check you angles first. The Blue is very specific on this.
     

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