SEAT BELT BOLTS...WHAT SIZE?

Early C Bodies - The Slab Side Years

  1. Richard Reau

    Richard Reau Member

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    Hello guys, I am making great progress on the '67 Newport Custom. Brakes are almost done, waiting on a small part from AMS Obsolete to complete those. Engine is running great, I have it painted, just waiting on a part from Steer and Gear in Columbus, OH, who handles everything related to power steering (and other stuff too I think). Two thumbs up to AMS and Steer and Gear for vintage car stuff...great people.

    SO, now I plan to get the front seat belts installed, and I have the parts, EXCEPT the bolts. Does anyone know the bolt size and thread count? Knowing the size will save me some effort in dealing with today's hardware guys, who can sell you a scented candle, but have no clue what size bolt you need, am I right? Photos to follow, and thanks as always, Rich in Tampa
     
    Last edited: Aug 14, 2019
  2. Richard Reau

    Richard Reau Member

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    Here are a couple of photos of the Newport's 383. Yes, the previous owner painted the engine bay black, so I just went with the theme. For the purists, I don't plan to take the car to Pebble Beach.

    103_0868.JPG

    103_0869.JPG
     
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  3. live4theking

    live4theking Old Man with a Hat

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    If I recall correctly they are not a standard bolt. I believe they are a shoulder bolt.
    Screenshot_20190814-193336_Chrome.jpg
    This is what I recall them looking like. This is from Year One. There is your threaded and pitch too. This is for a B body.
     
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  4. FURYGT

    FURYGT Senior Member

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    The seat belt bolts are a specific type of high strength bolt with a larger diameter shaft above the threads. You will need to get some used ones.
     
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  5. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    7/16-20. The best deal is to buy early Mustang bolts. Cost less, easier to find and they are chrome plated too. https://www.cjponyparts.com/amk-pro...oupe-convertible-fastback-1965-1966/p/HW1940/

    or Mustang Seat Belt Bolts Coupe / Fastback 1965 - 1966 - AMK | eBay

    I used these in my '65 Barracuda.
     
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  6. Richard Reau

    Richard Reau Member

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    Thanks guys....how about 7/16-20 grade 8 bolt from the hardware store? Hell, I ain't gonna break that, am I? And most likely some guy texting will rear-end me anyway. It's happened twice now, the first time totaled a restored '69 Volvo 1800.
     
  7. commando1

    commando1 Mr. Normal FCBO Gold Member

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    @stubs300
     
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  8. FURYGT

    FURYGT Senior Member

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    NO!!! Please look at one of the links to these bolts. They have a large shank above the threads and they are (as I already stated) a specific high strength bolt. Using the wrong bolt could end your life in the event of an accident.
     
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  9. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    You are really much better off using a real seat belt bolt. The shouldered seat belt bolt bottoms out and tightens against the floor nicely and allows the belt to pivot and "float" a bit. The bolt is also a locking type so it doesn't loosen up. The hole is also sized for the shoulder and I believe the whole assembly is stronger overall than just using a bolt.
     
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  10. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I see what you are trying to do there, but I'm gonna disagree with you. The thread size is a little tough to find. Later cars were metric (of course) and you really have to be looking hard to find the correct size. A simple search for this can be confusing... I know, I went through this myself.
     
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  11. dart4forte

    dart4forte Active Member

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    BE&A sells a seat belt bolt kit. In addition to the statement above the OE bolts are a resistant fit so they don’t back out. Use the correct bolts.
     
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  12. Richard Reau

    Richard Reau Member

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    Thanks guys. I looked at some of the bolts mentioned, and all are Grade 8, so the grade of seat belt bolts is grade 8, no question. Next, the question is...shoulder or no shoulder? It seems to me the shoulder allows the ring on the mounting flange that attaches to the floor to move freely, as Big John mentions, which presumably just allows for more flexibility of the belt flange, but in essence doesn't add any additional strength. So, with no shoulder, the mounting flange is firmly attached to the floor of the vehicle, so I don't see a compromise in safety there, and in fact it seems safer that the flange has less ability to move as opposed to moving around on that shoulder. Will the bolt back out? I can't see that as being an issue if the bolt is torqued down to 80 or 100 lbs, and if I use some threadlocker on the bolt, that problem is also solved. So, my plan is to get some 7/16-20 grade 8 bolts and get it done. I'll be fine. Thanks again for the input.
     
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  13. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Well... Yes and no...

    When you use a plain bolt rather than a specific seat belt bolt, usually it's a grade 5. The grade 5 is not as strong, but it will bend where a grade 8 will break.

    I'd strongly suggest you rethink this and go with a seat belt bolt. Don't forget you have a 1/2" hole in the belt that is designed to work with this shouldered bolt.
     
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  14. JC68vert300

    JC68vert300 Well-Known Member

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    Just contact Murrauy Park, he is a go to guy for c-bodies. I am sure he has a bucket of seatbelt bolts from cars he has taken apart.
     
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  15. commando1

    commando1 Mr. Normal FCBO Gold Member

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    It was a joke, John. It was a joke.
    And I agree only a bolt designed for seat belts can be used here.
    And it is a bolt.
    See that? I tied together three threads. :lol:
     
  16. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    OK, I get it now. :lol:
     
  17. stubs300

    stubs300 Senior Member

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    Heeeey, Howyadoin? Thanks, I'm on it!
    What is it with people? People come on here, ask a question about something and don't like the answers and want to use/do it their way, whatever! Do what you want! It's your car and your going to do whatever you want regardless of what others suggest or say. And if it doesn't work out the way you want or expected because you used the wrong bolt/part, don't come back here cryin and bitchin about it that it didn't work as you expected. There's a reason why they used special bolts, if you can grasp your head around that? Good Luck
    Mopar seat belt bolts at DuckDuckGo
    And if you don't like Duck Duck Go!
    Mopar seat belt bolts - Google Search


    13226884_1201753099837705_8000965357365451449_n.jpg
     
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  18. Richard Reau

    Richard Reau Member

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    Read my original post, I only asked what size. I didn't need all the Chicken-Little sky is falling stuff.
     
  19. Ripinator

    Ripinator Senior Member

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    Richard: Just go ahead with buying and installing the Home Depot bolts. In the meantime, why not order the correct bolts, so you'll have 'em on hand when you find out the HD bolts don't work?
     
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  20. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Don't take it any other but we're just concerned for your safety and the safety of your passengers. That's all. If this was a bolt hanging your alternator, it wouldn't get treated the same. Personally, I think a bolt will be OK, but I'm no engineer and I'll always come down on the side of recommending what looks to be the safest method. We'd all feel pretty bad if you or your passenger got hurt and something we said was "OK" wasn't "OK".

    Myself, I know I've pretty much used up my allotted "dumb luck" a long time ago, so I take that into consideration.
     
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