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Hot Rods Shoulder Anchor on fiberglass car for 3 Point Seatbelt

Discussion in 'The Hokey Ass Message Board' started by Tom Boutelle, May 24, 2019.

  1. Tom Boutelle
    Joined: May 24, 2019
    Posts: 4

    Tom Boutelle

    looking for information, pictures on how to anchor the shoulder point for a 3 point seatbelt on a fiberglass car
     
  2. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    Three ways . Mount to the top of seat frame like some passenger vehicles . Mount rollbar/roll cage and attached to bar with a mount. Fiberglass in a an attachment mount to the body.
     
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  3. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    One other thing depending on your type of body. If it has a tube inner structure , and thenyou can get to it, you will have to make a mount and attach it either by welding or bolting it to said structure.
     
  4. Tom Boutelle
    Joined: May 24, 2019
    Posts: 4

    Tom Boutelle

    If I fiberglass something into the pillar area, will it be strong enough? I've heard that legally it has to withstand 1000 pounds of pull force. Thanks
     
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  5. 325w
    Joined: Feb 18, 2008
    Posts: 5,131

    325w
    Member
    from texas

    No it will not be strong enough.
     
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  6. Tim
    Joined: Mar 2, 2001
    Posts: 9,546

    Tim
    Member
    from Raytown Mo

    We need a photo of your car. I’ve seen stuff that’s flimsy race weight stuff, and other than have a full metal substructure.
     
  7. 3banjos
    Joined: May 24, 2008
    Posts: 459

    3banjos
    Member
    from NZ

    If you can imagine dangling your car over the edge of a cliff, and only held by those anchor points without it falling, that's how strong they need to be.
     
  8. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    Yes you cannot just use a couple of layers and call it good.It has to be more engineered than that. They glass in body structures and door hinge mounts/body mounts/door catches etc. Look at how those are engineered .
     
  9. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    Personally I don't like fiberglass bodies but they use fiberglass in a lot of structural components wether cars, bucket trucks etc.
     
  10. G-son
    Joined: Dec 19, 2012
    Posts: 515

    G-son
    Member
    from Sweden

    You need the seat belt to be attached to the load bearing structure of the car, not the fiberglass reinforced plastic bodywork.
    Used to work with making fiberglass boats. Bottoms were about ½" thick solid laminate, probably 3-4 times as much as most areas of your fiberglass body. Still wouldn't trust it enough attach a seat belt to a small area of it. Steel buckles and changes shape but usually stays in one piece, fiberglass laminate is crushed to smithereens.
     
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  11. Gman0046
    Joined: Jul 24, 2005
    Posts: 5,482

    Gman0046
    Member

    I wouldn't trust my or my familys safety by attaching a seat belt anchor to fiberglass.
     
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  12. pitman
    Joined: May 14, 2006
    Posts: 4,627

    pitman
    Member
    from Hampsha

    Boat designer Dick Newick would use simple "statics-loading" eqn's, and a safety factor, which held up fine.
    Remembered were chain plates holding the mast up, thru-bolted in Hull glass.
     
  13. jaw22w
    Joined: Mar 2, 2013
    Posts: 734

    jaw22w
    Member
    from Indiana

    What are you trying to do? Make it safe or fool the cop that stops you?
     
  14. If you want a three point seat belt I would suggest you install some type of roll bar i a fiberglass cars, it's something none of us want to think about but the fiberglass cars usually de laminate and splinter in a accident or worse yet a roll over, another reason for the roll bar. HRP
     
  15. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,134

    Bandit Billy
    ALLIANCE MEMBER

    ^^^Good advise! I've driven rag top vettes for so long I don't give not having shoulder harnesses in a plastic car a second thought. But speaking of the plastic fantastic you could use the restraint seat idea offered after the 71 model year. Seats had a belt pass through in the corner of the seat back and the retractor bolted behind the seat through the glass structure and into the steel like the rag top frame did.
    upload_2019-5-25_13-7-26.png
    I've seen guys add these to hardtop (t-top) cars as well. Another idea borrowing from GM is the very rare 1st Gen Camaro back seat shoulder restraint. I actually had a 68 with this option.
    upload_2019-5-25_13-12-8.png
    In these pictures I stole from the internet you can see the retractor bolted in the back window.
    upload_2019-5-25_13-13-7.png
    You could do something like this with a bench seat and secure that retractor to a steel lateral brace under the deck. They reproduce the Camaro restraints.
     
  16. The 2 3rd row seats I got for my build the belts was attached to the frame of the seat it self.. Including the shoulder belt went over the back and down to the frame of seat..

    BUT ! keep in mind that these seat was SECURELY bolted to a metal floor...
     
  17. mohead1
    Joined: Jan 18, 2013
    Posts: 546

    mohead1
    Member

    Most safety harness equip must withstand a 5000 lb force

    Sent from my SM-G900V using Tapatalk
     
  18. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,530

    Blues4U
    Member
    from So Cal

    Any belt systems that attach to, or pass through, the seat back, must do so at or above the shoulder level. If below the shoulder level, in an impact the force will crush your shoulder.
     
  19. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,267

    Kan Kustom
    Member

    A well built fiberglass car in many case's is as good as a roll bar. I have had a couple customers that rolled and flipped the crap out of their fiberglass bodied cars and were solid as a rock and only scraped and scratched up the exterior. I used to hard kick the middle of the doors on the bodies we made and then asked customers what they thought their steel body would look like after that. Fiberglass got a bad wrap after all of the Corvette wrecks. Nobody stopped to think that most of those wrecks were at high speeds and we know what a steel car looks like after a high speed crash. On top of that Corvettes haven't been fiberglass for more years than they were at first.They call it sheet molded compound but all it really is is fiber reinforced polyester body filler pressed between two hot molds to cure. Drag cars usually have a minimum of fiberglass for weight savings and are counting on a roll bar. Engineer in some strength for attachments just as you would in a steel car. You wouldn't just bolt through a drilled hole in the sheet metal. Fiberglass is tough as hell when done right.
     
    Last edited: May 30, 2019
  20. dan31
    Joined: Jul 3, 2011
    Posts: 968

    dan31
    Member

    Look at seats from "Wise guys".
     
  21. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    There was a police officer in town that had a new built fiberglass Coupe hot rod , just put on road. Grabbed his buddy to take it out for a cruise. Got t boned at an intersection in the drivers door. A few days later they had the officer's funeral.
     
  22. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,267

    Kan Kustom
    Member

    T boned in a Henry Model A/ 32 wouldn't produce the same results ? You can get killed in anything with a bad enough impact. Especially square in your door.
     
  23. gene-koning
    Joined: Oct 28, 2016
    Posts: 1,213

    gene-koning
    Member

    A hard enough T bone in the drivers door (or a passenger door for a passenger) on ANY car will likely result in a funeral, even the toughest new cars & trucks. Over the years, there were a lot of round track race cars with lots of roll bars in the doors that didn't fair much better. There is simply not enough space and crush area in the doors to prevent this outcome.

    The concept of a seat belt restraint system is to keep the occupant in the seat and inside the passenger compartment of a vehicle in the event of a crash, because it is the safest place to be. There is no guarantee that a person that is kept in the seat and inside the passenger compartment will survive in a crash, but it does increase the odds of a survival dramatically over being left to fly about unrestrained in the crash. Increasing the odds of survival are the best we can hope for. The reality is that no one here will get out of this life alive, we are all destine to die.

    Outside of the act of surviving a crash, history has proven that seat belts have reduced the amount and the severity of injuries in non life threatening accidents by a very high percentage. I think that if I can reduce the chance or reduce the severity of injuries to myself and my loved ones in a crash, its worth the effort to at least try. Even if my design may be less then perfect (some have been tested), the odds are still better then having nothing at all. That is the reason I install seat belts with shoulder belts in everything I've built in the last 20 years. Gene
     
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  24. And yet there is always a dumb ass that proclaims that he'd "rather be thrown clear" in a crash. 50+ years of research with actual crash data with a lot of physics thrown in and they still know better.
     
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  25. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    Whoaaaaaaaaa:D Simmer down guys. I realize it is just not fiberglass cars that a t-bone could result in deaths. I was just pointing out a real world case that happened. Our views are shaped as we go through life and have real world experiences. I have years of doing fiberglass work on bodies and utility booms , inserts and buckets. From a dielectric, strength and superficial repairs standpoint . I just wouldn't want layers of chopped or woven matting and resin between me and someone's bumper. The safest hot rod would likely be a replica vintage race car with an up to date roll cage. So let me buy you a beer or two and have a laugh or two.
    .
     
  26. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,448

    41rodderz
    Member
    from Oregon

    Maybe I should find a pre 1965 State Police swat team armored truck. :p:D
     

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