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seat belt bolt size 12mm but what pitch?

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Old Feb 13, 2011 | 07:41 PM
  #1  
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
seat belt bolt size 12mm but what pitch?

Trying to replace these seat belt bolts since I'm running harnesses and the local hardware store doesn't care the 12mm in the proper pitch. Anyone have a clue what size they are? I don't need the shouldered factory bolt obviously anymore, and I searched for 45 minutes and can't recall what thread listed the bolt size so I can order it online.

Last edited by xpndbl3; Feb 14, 2011 at 06:05 PM.
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Old Feb 13, 2011 | 08:12 PM
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From: West of Toronto
Car: 89 IROC
Engine: 305 TPI / ZZ4 cam
Transmission: Stage 2 700R4, LS1 driveshaft
Axle/Gears: Strange 3.42 w/ Auburn
Re: seat belt bolt size....14mm?

Hey,

Do you need an answer tonight or will first thing tomorrow morning do?

Car is in the garage.
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Old Feb 13, 2011 | 08:16 PM
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size....14mm?

morning is fine, I will try to hit up fastenal and hopefully they will stock the nuts so I can check out what fits. Anything to be done with these torx. The problem stems from my new corbeau seats, I don't have enough room with the seats installed to get a torx bit in there compared to just a regular wrench....so the seats take 2 hours to install around the cage bars. So I can't wait for the regular bolt to get tossed in.
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Old Feb 13, 2011 | 08:21 PM
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From: West of Toronto
Car: 89 IROC
Engine: 305 TPI / ZZ4 cam
Transmission: Stage 2 700R4, LS1 driveshaft
Axle/Gears: Strange 3.42 w/ Auburn
Re: seat belt bolt size....14mm?

Just to confirm,you're referring to the bolt that attaches the bottom seatbelt(retract mechanism) to the body?
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Old Feb 13, 2011 | 08:43 PM
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size....14mm?

yes it sits next to the seats on either side where your butt would go
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Old Feb 13, 2011 | 11:08 PM
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From: West of Toronto
Car: 89 IROC
Engine: 305 TPI / ZZ4 cam
Transmission: Stage 2 700R4, LS1 driveshaft
Axle/Gears: Strange 3.42 w/ Auburn
Re: seat belt bolt size....14mm?

Forgot I had a spare set of seatbelts in the basement.

The hole is 13mm wide.

So I guessing it will be a 12mm bolt.
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Old Feb 14, 2011 | 12:15 AM
  #7  
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size....14mm?

thanks but I was looking for the pitch of the threads as well, in the morning I'll be taking one of the bolts to a local bolt supply company and hopefully they can match me up something as long as I don't have to buy a quantity of 50 or something crazy like that
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Old Feb 14, 2011 | 01:18 PM
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From: Levittown Pa
Car: 89 Iroc Convertible
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.27 Posi 9 bolt PBR
Re: seat belt bolt size....14mm?

The lower retractor unit is held on by a torx bolt.I believe its a T-47
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Old Feb 14, 2011 | 05:59 PM
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size....14mm?

again, i don't need to remove the bolt, it's sitting in my hand and I know how to remove a torx bolt. it's 12mm something but the thread pitch did not line up with 1.5, 1.75 or 2.00 Not sure where to go from here, other than tapping it for 1/2-13 and double nutting it on the back, probably going to be the best solution
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Old Feb 14, 2011 | 08:08 PM
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From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: seat belt bolt size....14mm?

its a bolt, if you turn it to the left, it loosens, right, it tightens.....

i took one out and looked into this for you, the thread is almost exactly the same as 7/16-14, but thats just a hair smaller and is a bit sloppy in the holes.

defiantly not 1, 1.5, 1.75, or 2, but it just might be 12mm 1.25 pitch. I dont have one of those bolts handy, but may be able to get my hands on one tomorrow. i think thats it. if its not, its a special thread and will be a ***** to find.

you can get small quantity's from McMasterCarr, 5-10, or singles of really large ones

Last edited by //<86TA>\\; Feb 14, 2011 at 08:13 PM.
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Old Feb 14, 2011 | 09:00 PM
  #11  
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size....14mm?

Ya fastenal is a pretty big bolt company around here and they had nothing on the shelf or in their huge catalog to order it up. Guy basically told me to drill it out and re-tap it for the next size larger and double nut the rear of it so it doesn't pull through.
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Old Jun 12, 2012 | 09:04 PM
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From: Washington D.C.
Car: 1985 Z28
Engine: LT1
Transmission: T56
Axle/Gears: fourth gen 3.42
Re: seat belt bolt size....14mm?

Originally Posted by //<86TA>\\
its a bolt, if you turn it to the left, it loosens, right, it tightens.....

i took one out and looked into this for you, the thread is almost exactly the same as 7/16-14, but thats just a hair smaller and is a bit sloppy in the holes.

defiantly not 1, 1.5, 1.75, or 2, but it just might be 12mm 1.25 pitch. I dont have one of those bolts handy, but may be able to get my hands on one tomorrow. i think thats it. if its not, its a special thread and will be a ***** to find.

you can get small quantity's from McMasterCarr, 5-10, or singles of really large ones

Any chance you can confirm exactly what the bolt is? I'm in a similar situation as the OP (sorry for a thread from the dead)

Steven
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Old Jun 20, 2012 | 10:24 PM
  #13  
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From: Syracuse NY
Car: 84 Z-28
Engine: 305 HO
Transmission: r-700
Axle/Gears: 3:73
Re: seat belt bolt size 12mm but what pitch?

A #50 torx bit will do the trick!
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Old Jun 21, 2012 | 09:00 PM
  #14  
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From: Orland Park, IL
Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
Re: seat belt bolt size 12mm but what pitch?

Drilled it out and welded a grade 8 nut to the backside and then double nut'd that with locking nuts.
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