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Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Does anyone know the specs for the front seat bealt bolts (all three, 2 lower, 1 upper)? PET just names them but doesn't give the size or pitch.
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1987 951 - M193 Version for Japan

Lizard · Posted: Sun Jan 28, 2007 7:58 am Post subject:

this is a rough guess but I would be saying M10 w/ 1.5 pitch, could be an M12 though
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3 928s,

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

It's weird that PET doesn't disclose the info. Is there something special about the bolts? I'm assuming they are just metric 12.9?
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1987 951 - M193 Version for Japan

Ozzie · Posted: Sun Jan 28, 2007 8:28 am Post subject:

I would be more inclined to say 14mm x 1.25 pitch
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Smoothie · Posted: Sun Jan 28, 2007 8:40 am Post subject:

Diesel and myself found them to be SAE 7/16-NF20, while gohim says M11x1.25 - http://www.924board.org/viewtopic.php?t=4027
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Ozzie · Posted: Sun Jan 28, 2007 10:19 am Post subject:

Just was out in the shed and check with the vernier 11mm.
Cant find the screw pitch guage but 1.25 looks right.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Thanks Ozzie, and everyone else.
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1987 951 - M193 Version for Japan

Smoothie · Posted: Sun Jan 28, 2007 1:53 pm Post subject:

I'm still real sure it's 7/16-20.
I was as sceptical as anyone to think they'd be non-metric, but I remember checking one of the belt bolts against both 11mm and 7/16" taps and found the thread pitch fell between 2 metric sizes (larger than 1.25, but smaller than the next metric tap), but right on with the 7/16-20 tap. I checked twice and started to walk back, then turned around and checked it again. -Same result of course.
Here're some VW'ers that found the same (7/16-20 seat belt bolts on their VWs) - http://www.autoforumz.com/Seat-Belt-ftopict86848.html
M11x1.25 might be close enough to use, but really they are 7/16-20.
Listen to that little voice in your head...
"it's 7/16-20 (and at least grade 5)...7/16-20..Smoothie says they're 7/16-20... ...

..and it's all because of Ralph Nader...Ralph Nader did it...did it..did it..."
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Ozzie · Posted: Sun Jan 28, 2007 2:47 pm Post subject:

Usuaully metric comes in even numbers 6,8,10,12 etc so unusual to have 11m.
I'd normally go with smoothie on 7/16 UNF apart from the fact that the car is Euro origin (read metric).
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Wow, who knew this would be such an interesting topic? I find it hard to believe any bolt on a German product would not be metric, but go figure.
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1987 951 - M193 Version for Japan

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Smooth dog, you are pretty goddamn funny. Chrenan, you have a PM.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Smoothie · Posted: Tue Jan 30, 2007 5:56 pm Post subject:

Just in case of any straggling non-believers...

2 pics - first with a metric 1.25mm/thread tap against a seat belt bolt (I tried to include the tap size in the pic, but all you can see of it (just barely) is ",25") -

There you see the threads meshing at the right side, then going gradually out of alignment until they're almost point-to-point at the left.

Then the same bolt held against a 7/16NF20 tap - you see the threads mesh all the way across (again I tried to include the tap size in the pic - what's barely visible of it is "16NF2" and "JAPAN" below that) -

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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Ozzie · Posted: Tue Jan 30, 2007 8:35 pm Post subject:

Thanks - now that is sorted.
(I do have another car with different bolts, can get confusing)
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Thanks Smoothie. This will be a good reference when the question is ever raised again.
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1987 951 - M193 Version for Japan

Smoothie · Posted: Wed Jan 31, 2007 2:58 am Post subject:

Here're DOT rules on seat belts -
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/571.209.htm
Scroll down to "(f) Attachment hardware" - They say "shall have 7/16- 20 UNF-2A or 1/2-13UNC-2A attachment bolts or equivalent metric hardware". -Still a mystery why they went with the SAE size - maybe because M11 is an oddball size and 7/16NF20 shouldered bolts would be cheap an plentiful?..
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox