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Technical Shoulder belts in a convertible .

Discussion in 'The Hokey Ass Message Board' started by VANDENPLAS, Apr 25, 2020.

  1. CEEB3C68-A60B-47F1-81D8-59A7DCD339F3.jpeg C92BA226-AE61-4AFF-905A-57795399EB84.jpeg FF2B8687-6FEB-43E2-A747-AE902F97589E.jpeg 0E602BA8-22AB-4E96-8F86-CA200792C04C.jpeg Ok my home renovations “ should be” coming to an end in the next 2-3 weeks.
    Just in time for the good weather.
    I’m going to be taking my 64 merc out.
    The wife wants me to install seat belts.
    She’s quite adamant on shoulder belts front and rear.
    I’ve installed them in my 50 Chevy relatively easy.
    How do you install shoulder belts when you don’t have a roof or sail panels ?
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 49,262


    You take off the quarter panel interior trim, and figure out how to weld on a bracket to support the end of the shoulder belt, or the guide that holds in in place.
    pitman and R A Wrench like this.
  3. I get that
    I used vw belts on my 50 and mounted them like that
    But they will have to mount either below the height of the seat

    any belts like that ?
  4. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,220

    oldiron 440

    I think the factory belts also rely on the seatbacks locking. So I'm not sure if it would be safe to rig up a shoulder belt or not without changing the seats.
    loudbang and squirrel like this.

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 49,262


    Look at how they do belts in modern convertibles. They generally have a guide on the seat back, and the belt is mounted at the floor.

    There are some vehicles with the belts built into the seats--for example, 99-06 Chevy trucks. See how they work. But they are seats that don't tilt forward.

    I would just leave the car alone, and work on the concept of accepting risk.
  6. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,220

    oldiron 440

    My 64 has the optional seat belts.
    VANDENPLAS likes this.

  7. can you take a pic of them?

    I’m fine with lap belts front and rear
    But I married a “ oh no “ worst case scenario type person
    Which isn’t all bad
  8. Phil P
    Joined: Jan 1, 2018
    Posts: 350

    Phil P

    On my ot sports car the mount is lower than almost every bodys shoulder, in an accident there is going to be some compression of your shoulder. It was a stock set up in 1990.

    kbgreen and loudbang like this.
  9. bigdog
    Joined: Oct 30, 2002
    Posts: 663


    The anchor point for the shoulder harness should be above shoulder level. Otherwise in an accident the harness will pull down on your shoulder and compress your spine, not a good thing. modern cars have taller seats so on convertibles they run the belt through a guide on the seat like Squirrel said.
  10. Look at some seat belt sites like Wesco and Julianos to see what they say. They have links and installation information.
    loudbang and VANDENPLAS like this.
  11. This. Anything where the upper mount is not high enough can cause a spinal injury in an accident.
    loudbang, Just Gary and bobss396 like this.
  12. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,567


    Just a outside the box thought, how about a roll bar then mount shoulder harness/seat belt to it just like in the race cars.

    loudbang and bobss396 like this.
  13. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    from Quincy, IL

    CD917BC3-CED9-4071-B1BF-2E2DF1435297.jpeg EFCAEAA1-C9F7-4C61-89B8-B8F712FA6810.jpeg C7FD402F-8EC7-4522-BBCF-F2038F581B06.jpeg A64AD6B0-C0DD-4FD1-9D0A-464B8264D3F1.jpeg 5EFC7E9B-771B-48FD-9EC9-36A80DE2A60E.jpeg 840F8CAE-7CB7-4EC8-ACA5-3F54361430AB.jpeg @VANDENPLAS
    Take a look at the very popular Chrysler Sebring convertibles of the 2000’s era ......they are two door, have folding seats with belts and shoulder harnesses. Seats with integral belts have substantial anchor points for obvious reasons.

    Mrs Hnstray is pretty concerned about belts/harnesses being in cars she rides in. So, I ‘engineered’ them for my ‘38 Buick coupe. It was timely as it was ‘gutted’ for a new interior anyway. It now has later model Buick Verano bucket seats in which belts/harnesses ARE NOT integrated. I fabricated reinforcement plates for the B pillar, up high for the shoulder belt anchor. (Note: the upper reinforcement plates are both welded and panel adhesived to the B pillar/roof rail. The pop rivers were used solely to locate the part accurately.) The seat belt retractor is anchored to the to the floor and base of door pillar with two plane reinforced mounts and belt connectors between the seats. The small ‘arm’ at the upper mount was to keep the belt vertical for proper inertial lock operation in the reel.

    Now, the only hazards that remain are: stock non-collapsible steering column, no air bags, no side impact door reinforcements, no lane change notification, no automatic braking.....etc. But, she is comforted and I think what has been installed can have benefits in a minor/moderate collision. No harm was done. But as Squirrel has to accept some risk in life.

    Last edited: Apr 26, 2020
  14. I followed the height that Wesco recommended and the retraction on a hard stop is good. You may not get that if the 3rd point is too low.
    loudbang likes this.
  15. rdscotty
    Joined: Sep 24, 2008
    Posts: 195

    from red deer

    I am in agreement with Squirrel and Hnstray to look at belts self contained in the seats. Chrysler Sebring convertibles had them.
  16. ken bogren
    Joined: Jul 6, 2010
    Posts: 906

    ken bogren

    On some newer OT convertibles there was a small tower at the B pillar where the shoulder belt was attached.

    On my 90 mustang the belt was attached at the front of the well for the top mechanism.

    If I recall right, on cars like the early 70schevelles, cutlass etc the shoulder belt came from behind the outside corner back seat backrest, a really unwieldy arrangement. description here, scroll down a ways >
    loudbang and VANDENPLAS like this.
  17. Do you have access to look at an off topic 1994-2002 Camaro/Firebird convert? Their shoulder belts are mounted in the rear quarter with a guide on the side of the seat back.
    VANDENPLAS likes this.
  18. ramblin dan
    Joined: Apr 16, 2018
    Posts: 2,592

    ramblin dan

    It's funny when I read this I remember when my kids were little telling their friends that their dad had a car with no seatbelts in it.
    loudbang, VANDENPLAS and 1934coupe like this.
  19. I'd be telling "my" woman so don't go repeating. There's no such thing as sky hooks.
    I feel for you. Good luck
    loudbang likes this.
  20. I’ll look into these suggestions.

    trust me when I say it’s not her, it’s the kids.
    She wants them safe.
    She loved running around in my old stuff.
    Bench seats, no safety belts, snuggled up close not caring about a thing.

    now we got kids that gotta be transported across hells half acre everyday so safety has now become a thing.
  21. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,974

    from Berry, AL

    I think if I were to do anything it'd be lap belts and be done with it. Shoulder belts, just about anyway you do them, are going to look out of place in that car. I think I'd rather be able to lay down in the seat if it flipped on its top side instead of being the highest point to hit and drag.....
  22. BJR
    Joined: Mar 11, 2005
    Posts: 6,991


    I think in a car not engineered for shoulder belts, in an accident it could do you more damage than just lap belts.
    OLDSMAN, wvenfield and loudbang like this.
  23. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    from Quincy, IL

    The dynamics of a crash that results in a rollover will not permit a passenger to choose how to place his/her body during the event. One’s body will be thrown in whatever direction the vehicle’s movement propels them and at whatever speed the vehicle is traveling at that instant. To think that a passenger has the strength to willfully resist those forces is unrealistic.

    Short of having race car spec seats, harnesses/belts and a roll cage, an occupant is at the mercy of whatever forces are generated in a collision or upset.

    Seat belts, at a minimum, certainly have been shown to mitigate severity of injuries most of the time and keep a body from being ejected from the wreckage. Of course, there are the ever popular stories of (insert name or relationship here) who survived precisely because he/she was thrown clear of the wreck. And that no doubt has happened. But far, far more often the injuries were more severe or fatal when an occupant is ejected....often being crushed by the very vehicle from which they have just exited.

    Last edited: Apr 26, 2020
  24. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,247

    Ned Ludd

    The sources I have for race harnesses require that shoulder belts pull down at an angle of around 45° as measured from the seat back. It makes sense to me, even in the absence of an anti-submarine strap, that the shoulder belt should tend to push your butt down onto the seat rather than let it travel forwards under the lap belt. This assumes, however, that the belt anchor is very close behind the seat, as any deformation will tend to pull the belt more horizontal. If the anchor is further back I'd think that the angle of the belt should be more horizontal to begin with. Either way, it suggests that it would be perfectly effective to anchor a shoulder belt high on the inner quarter.

    I have looked at engineering a seat with built-in seat belts, as I think it would be very useful in a hot rod or other early-type car. Everything then comes down to fixing the seat to the floor and frame, and the integrity of the rest of the body does not bear on the efficacy of the belts. It's fairly simple structural engineering. It isn't even necessary to know what kinds of impacts/decelerations to design for if the principle is followed that it doesn't make sense to design for forces much greater than the belts themselves can handle. I had a go at this, but I found that a door latch as I'd suspected might be just the thing to lock an adjustable and tiltable backrest wouldn't be quite op to the job. I've since wondered if using a light-duty steering box on the tilt action might offer some leverage to a door latch.
    Hnstray and 1934coupe like this.
  25. gatz
    Joined: Jun 2, 2011
    Posts: 1,579


    A few pix of the Chrysler Sebring (power) seats...
    If you decide to go this route, make sure to get the "module" that controls it.

    Chrysler Sebring Seat Tilt_2.jpg

    Sebring Seats_3.jpg

    Approx 30° forward tilt.

    tilt angle.png
    Ned Ludd likes this.

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