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Seat belts and seat anchoring in a fiberglass car...

Discussion in 'The Hokey Ass Message Board' started by resinaddiction, Aug 18, 2014.

  1. resinaddiction
    Joined: Jul 18, 2014
    Posts: 2

    resinaddiction
    Member

    I'm in the process of building a '32 3 window; Downs body...I apologize if this has been asked or discussed, I did a search, but couldn't find anything.
    The floor is fiberglass with coremat (?) sandwiched in it, how does one anchor the seat and seat belts to the floor?
    I've considered getting a piece of plate steel and laminating that to the bottom of the body, that way the body mounting bolts would attach the body (and the steel) to the frame, and then I could attach the seat and seat belts to the floor and the steel plate, (and ultimately the frame), but some people are telling me that's overkill and all I need to do is just drill through the floor and since it has the coremat laminated in it, as long as I use some really big washers on the backside I'll be fine.
    What is typically done?
    And since I'm going to be driving along in a big fiberglass box, do I really need to worry about this?
    Thanks


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  2. 54 Chevy
    Joined: Sep 4, 2010
    Posts: 357

    54 Chevy
    Member

    I would make a steel plate 3" × 5"or so and drill a hole thru the center. Put it under the floor with the seat belt mounting bolt thru the plate.​
     
  3. You could mount them through the floor with small plate or large washer as normal. Then have some 6" or so pieces of coated or stainless cable with eyelet's made up. Bolt one end to the belt and washer under the floor and the other to the frame. Then if the washer pulled through the glass floor in a crash the cable would catch and hold you in the car. You would have to play with it to make it clean though.
     
  4. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 7,561

    mgtstumpy
    Member

    A bit hard to visualize without seeing the body and internal structure(s). If not already done I would steel the body out and make an internal structure with 3/4" RHS and run 2"x1" RHS across the floor to mount seats and provide lower seat belt anchorages similar to where they are normally located. I would also reinforce the 'B' pillar area and triangulate braces to support a shoulder mounting location (3 point seat belts). The RHS would be glassed to the body and also secure the body to the chassis via bolts, reinforcing the entire structure; body, framework and chassis. I would assume that the "B' pillar is strong as the doors swing off them.
    Down here DOT seat belts are mandatory along with suitably engineered mounting points. All closed cars must have 3 point belts in external seating positions; open cars require only 2 point belts.
    Corvettes for example have rectangular mounting plates under floor to spread the load. The corners have a 5/16" radius with edges against floor chamfered so there is no significant load on those points in an accident. Mounts are 3/16" thick.. Bolts should be 7/16" UNF SAE grade 8. The belts need to be comfortable and safe.
    Here's an example of a steelout to assist.
     
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  5. camerl2009
    Joined: Jan 26, 2014
    Posts: 182

    camerl2009
    Member

    when I build my t bucket I will be bolting my belts to the frame but mine will also have a 10 point cage in a open top id rather be thrown from the car as well t buckets don't look all that good after a accident
     
    Last edited: Aug 19, 2014
  6. I fit belts as part of my job, our New Zealand laws on there placement are similar to Assuie.
    Do not mount them to the chassis as in a crash and the body brakes its mounts the belts with you in them will try and keep the two together.
    You really need to steel out the body to have the belts anchored to it securely. If you have to mount any plates to the floor you should use doubler plates that sandwich the fibre glass, these plates should be about 3''x4'' or larger. JW
     
  7. loudbang
    Joined: Jul 23, 2013
    Posts: 22,215

    loudbang
    Member

    Unfortunately I had the VERY UNPLEASANT task of picking up the exposed BRAIN MATTER left over from a "T" bucket driver/builder. He was traveling on an interstate about 60 MPH (this was back when the speed limit was still 55) when the poor job he did welding the radius rods bracket to the frame came apart and the car did a violent right turn right into the guard rail. The car was stopped by the guardrail but he was vaulted out of the car over the windshield down an embankment onto some rocks.

    When we got to him he was just barley breathing and when I slid my hand under the back of his head, while we were moving him the the transport basket, my hand went right into his brain cavity which is something you NEVER forget and comes back to you in your dreams for life.

    After he was transported I was assigned the task of collecting the pieces of his brain not something one wants to do more than once.

    The moral of the story was the right turn scrubbed off most of the speed and the car didn't have much damage and yea his SEAT BELT WEARING PASSENGER walked away with no physical injuries but you can bet he will never forget his buddy flying out of the car to his death.

    So if you don't care if you die from not wearing seat belts think about the effect of your manner of death on the people that have to clean you off the roads.
     
    26 T Ford RPU likes this.
  8. krylon32
    Joined: Jan 29, 2006
    Posts: 5,870

    krylon32
    Alliance Vendor
    from Nebraska

    I use 1.5 X3/16 wall square tube and tig weld in 1/2 in bungs for bolting on the belts and secure the tube on each end using the body bolts into the frame just before the kickup.
     
  9. Wtf guys ?!?!

    Fab a mount off the frame that will catch the seat belt bolts. If you are clever and can measure you can use it to mount the rear of the seats too.
     
  10. Well, all that being said, here's what I did. laid down 3/16 by 2 inch steel bars and drilled through them and through the frame and bolted them in. It all doubles as a body mount also. If I crash, I'll take my chances with the car around me. 001850.JPG 001840.JPG mirrors 002.jpg
     
  11. F-ONE
    Joined: Mar 27, 2008
    Posts: 1,859

    F-ONE
    Member
    from Alabama

    IMHO a closed car or roadster with roll bars needs some type of restraint system, if only a lap belt. If it rolls the occupants wind up being thrown out a door or window half in half out and the car will rollover on them.

    I think the OP may be over thinking this, two plates bolted together with the floor sandwiched in the middle would make a suitable base for a lap belt. If it pulls through on impact, seatbelt performance will be the least of the problem.

    On an open car, especially like a T with no roll bar, the occupants may be better off unrestrained. If it rolls over, which they often do when they go off road, it will roll over onto the strapped in occupants because on a lightweight roadster they are on the car instead of in it..

    Helmets are a very good option. But who does that?

    Well it just was not his day was it? When it's not your day it's not your day.

    I saw a guy killed buy an airbag in a new "big" luxury car. He was restrained...did everything right and was in a "safe car." Both that were in the 2 seater import that crossed into his lane got off with broken legs.
     
  12. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    I have to echo what 26 T Ford rpu said, DO NOT PUT YOUR SEAT BELTS TO THE FRAME on a fiberglass car. If you wreck and the body comes loose it could cut you in half ! You want to be strapped to the body, not the chassis.

    Simply run your bolts down through your floor and put either some small plates or large fender washers under there and call it good. I know we will get some arguments on that, but, believe me, you do not want to be strapped to the chassis if this happens.

    Don
     
  13. loudbang
    Joined: Jul 23, 2013
    Posts: 22,215

    loudbang
    Member


    Lol about what I expected some people will never learn. So for others that are contemplating not using them and the "common wisdom" of old spouted about getting thrown out is better, in this age of the internet with all kinds of info available at your fingertips, a simple search will get you the info, that contrary to popular opinion, persons ejected from a vehicle in an accident have about a 60% GREATER chance of sustaining FATAL injuries than occupants that remain in the vehicle.
     
  14. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    Wearing a seat belt in an open roadster is simply a matter of personal choice..........no different from choosing to wear a motorcycle helmet or not to wear one. I don't wear a belt in my 27 and won't wear one in my rpu when it is done. Strapped in, you are the tallest thing in the car, and if it lands upside down..................:oops:

    [​IMG]

    But that is just my philosophy.



    Don
     
  15. You raise a good point with an open car Don, one I have been tossing around for my own T RPU. I will fit laps and will see. That looks a bit like a New Zealand licence plate on that car. JW
     
  16. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida


    I think the car once belonged to Brian Setzer of the Stray Cats, but when it was wrecked it belonged to another guy. I sort of remember Sweden, but could be wrong about that.

    [​IMG]

    Don
     
  17. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,007

    porknbeaner
    Member

    Actually in Missouri it is not a choice. Helmet or seat belt. it is a funny thing, a pre '65 car is not required to have seat belts but the way the law is written you are still required to be wearing one while the car is in use. granted not enforced much but they can still ticket you.

    A lap belt in a roadster is a good thing because you can fold over with one, but a shoulder harness is not a good idea unless you have a roll bar. If you have a shoulder harness in this state you are required to use it, but the only requirement is a lap belt if that is all that you have.

    As for the question I suppose that if you spread the load out a seat belt will hold in a glass car so a couple of plates with the floor sandwiched between would probably work or one could do ad 31Vicky suggests and built a mount into the frame and use it to anchor the seat belt and the seat.
     
  18. trollst
    Joined: Jan 27, 2012
    Posts: 1,458

    trollst
    Member

    When I was very young I owned a Vauxhaul viva, a 65 model, flimsy little car to say the least. I head onned a kenworth on a logging road, and thank god neither the guy with me and myself were not wearing belts, the doors spit open, I went one way and dave the other, crawled up the bank to see a white ball under a kenworth, I would have been dead for belts. HOWEVER, I wear them religiously, always have, never had a crash since, can't say whether either way is better. BUT, hot rods are like motorcycles, you're gonna get hurt bad no matter what, there is no correct choice in my opinion. Just my two cents, after having been there once already.
     
  19. If the car got rear ended and the body sheared its mounts the belt wearer would then take all the force if they are attached to the frame, mount them to the body only. JW
     
  20. Boy I gotta think that if it broke the body mounts, then the body mounts need much better thought. Something a little better than 3/8" bolts tapped into the frame rail.
     
  21. And that is something only you and me can control on our cars. JW
     
  22. Six-Shooter
    Joined: Jul 12, 2010
    Posts: 341

    Six-Shooter
    Member
    from Ohio

    I installed a pair of seat belts in my T-bucket. It wasn't required by Ohio law since the "original" 1923 Ford was not manufactured with seat belts. I prefer to use them in the event I might have to go off the road but hopefully stay upright. Each belt is attached by way of a carabiner to a single eyebolt behind each seat. The eyebolt runs through the wood floor and has a wide washer on the bottom side. 100_6381 (1024x641).jpg 100_6380 (1024x768).jpg
     
  23. I used a flat piece of 1/8 inch strap about 3 inches wide from one side to the other, in the middle was a hump to double as a trans tunnel mounting point. Instead of having one single point which all the force is loaded it has 3 more to go with it to distribute the load in the event of an accident.
     
  24. resinaddiction
    Joined: Jul 18, 2014
    Posts: 2

    resinaddiction
    Member

    The car is a Downs body, so it's glass with an inner tubular steel framework on the sides and roof, that has wood attached to that. What I was planning on was putting in 3 point belts with the upper mount welded to the (sq.) tubular steel in the body sides (behind the doors and above the seats).
    The tubular steel framework is bolted to the frame both in front of the doors and behind, so (in effect) there is a tubular steel cage surrounding the interior that is securely attached to the frame, but if the body was sheared from the frame (the bolts broke), what I'm hearing is I wouldn't want the belt anchored to the frame more securely than the body? So probably use the plates sandwiching the floor to reinforce the mounting of both the seats and belts as referenced above...or anchor the lower mounting points for the belts and seat to the same plate that the bottom of the cage is attached to (which in turn is bolted to the floor)?



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  25. That sounds good. JW
     

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