best/safest way to mount 4 point harness
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  1. #1
    Fellow Frogger!
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    Default best/safest way to mount 4 point harness

    hey, as the topic name states, what is the best way to mount a harness to the parcel tray, as i do not have a roll cage.

    they are 4 point harness, which i am picking up today, so i was wondering how it should be done, what is needed etc.???
    as i have some sort of an idea but im not sure how safe/good it will be, its for my 504ti...

    so any surggestions would be great....

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    mike
    1972 504 Ti

  2. #2
    Fellow Frogger!
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    parcel shelf... no no no - you want the point of attachment a bit lower than that.

  3. #3
    Fellow Frogger! johnh875's Avatar
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    From memory somewhere between horizontal and 15 or 30 below - an easy option would be mount to the seatbelt mounts but that is too low. Parcel shelf would be a good place I would have thought, properly reinforced of course (eg don't use child restraint anchor!)

    Mike is this for motorsport use? Probably the best thing is to refer to the CAMS manual.

  4. #4
    1000+ Posts tekkie's Avatar
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    Mike,

    your harness will have an instruction manual inside. The manual will cover the recommended, acceptable and non-acceptable angles. It is paramount to maintain correct positioning of the belt buckle, it should not rest on your stomach.

    With regards to the angle of the rear belts and relative positioning to the rear parcel shelf it depends on the height of the driver and the seat.
    It is unlikely you will be able to use factory mounting points, but you can custom make a flat panel of say 3~5mm sheet of metal on the far side of the parcel shelf that complies with CAMS manual. If in doubt speak to Bond Rollbars or similar specialist. It may look strong but may fail when you need it most.
    .
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  5. #5
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    from what i've read/heard parcel shelves are generally there to hold the sides of the car together (think it was from a BMW 318 article)...

    i've got both of mine going to the rear right top seatbelt mount & its "OK" however i'm not 100% happy with it & will be probably putting a bar between the two top rear seatbelt mounts & doing it properly...

    It might cost an extra $400, but whats the excess on your hospital cover?

  6. #6
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    ok, i will look in to the mounting of the back seat belt points,

    this was an idea i had, weld in a piece of square tubing under the parcel tray, from one side of the car to the other, inturn creating a strong ancher point.

    ive read the instructions that came with the harnesses, but all it says is to use a reinforcing plate 3mm*50mm*75mm on each bolt under the parcel tray.

    mike
    1972 504 Ti

  7. #7
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    Quote Originally Posted by Mike L
    ok, i will look in to the mounting of the back seat belt points,

    this was an idea i had, weld in a piece of square tubing under the parcel tray, from one side of the car to the other, inturn creating a strong ancher point.

    ive read the instructions that came with the harnesses, but all it says is to use a reinforcing plate 3mm*50mm*75mm on each bolt under the parcel tray.

    mike
    Just follow the iinstructions, if your body pulls these out of the parcel shelf you would be in a pretty bad way!
    Graham

  8. #8
    Gone Fishin' Ray Bell's Avatar
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    And if you pull the shelf out of shape, it's probably been very good for your survival!

  9. #9
    Fellow Frogger! WAUTY205's Avatar
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    Quote Originally Posted by Mike L
    ive read the instructions that came with the harnesses, but all it says is to use a reinforcing plate 3mm*50mm*75mm on each bolt under the parcel tray.
    mike
    I'm almost sure that this is also the recomended size given by CAMS. I have my harness mounts through the vertical pannel behind the rear seats with backing plates from the boot floor to the under side of the parcel shelf. The scrutineers have no problem with it as it far excedes the recomended requirements, but I do intend running a tube between the rear cage mounts & fixing them to that. -Will
    1990 205Gti
    1976 504 rally car (currently out of action)

  10. #10
    BiX
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    I ran a strip of steel, 50mm by 3mm by 900mm across the back, and have both sets of harnesses and another 3 bolts in it (8 bolts total). It will depend on your seat height and parcel shelf construction. Also try as mentioned above, with the box section. The 75 x 50 x 3 is the min spec for each eye bolt. I have been told that you can cross them and mount to the rear seat belt lower mounting points, but was a bit wary as to the high downward angle.

    Thats said a cage will go in soon, and the harnesses will mount to this.

  11. #11
    Gone Fishin' Ray Bell's Avatar
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    I don't understand how using a big washer under a bolt that's in shear can do much good...

    Must be me, I guess.

  12. #12
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    Quote Originally Posted by BiX
    Also try as mentioned above, with the box section. The 75 x 50 x 3 is the min spec for each eye bolt. I have been told that you can cross them and mount to the rear seat belt lower mounting points, but was a bit wary as to the high downward angle.
    That did not refer to box section, rather a small piece of steel plate 75mm long, 50mm wide and 3mm thick.

    As mentioned earlier, using lower rear seatbelt mounts is not good, if you do use the belts they will put tremendous downwards force on your shoulders.

    Ray are you referring to the reinforcing plates required underneath the parcel shelf? The force applied to a harness bolt could be compared to pulling a nail out with a claw hammer the bolt is not purely in shear, even though the moment would only be a few millimetres. If the reinforcing plate is bolted to the parcel shelf it also spreads the shear load too, so the sheetmetal will be less liable to tear (and thus release the bolt).

    Something else to consider is racing seats where the seat back bolts to a roll cage member behind the seat it helps a lot in side impacts, you would be surprised how much seats flex.

  13. #13
    al
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    Mike, there are a company that advertise in australian classic car that specialise in fitting aftermarket seats and harnesses... Perhaps it would be worth having a chat to them to get some opinions?

    I'll see if i can find their details when i get home.
    405 Mi16 - Sold - Now back
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  14. #14
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    Hi Mike,
    i put my 4 point harness in my 504 using the two floor seatbelt bolts, and then buying plates and bolts from Revolution Racegear in Ringwood whuich i bolted into the parcel shelf. Have had no problems, and the bolts yo buy for seatbelts are all the same thread size so they will fit. I'd put the parcel shelf bolts fairly close together so the harness doesn't slip off the headrest often.

    Andrew

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