Interesting Bolt Head Marking find for you "Fastener Guys" . . . .

Interesting Bold Head Marking find...

Being in the Fastener business I get calls occasionally asking if the Bolt Kits I sell have the correct GM Head Markings. At that point I have to explain that GM Used quite a few manufactures when it came to the bolts they used and this little post will shed some light on that topic.

While cleaning my Window Hardware on my 70 Stage 1 I noticed that there were TWELVE different head markings on the 30 + bolts that are found inside of a Buick Door. Now for the most part there are only 3 different sized bolts being used inside the doors so to have 12 different markings was pretty interesting even to a guy that knows GM used a few different companies to provide these fasteners. I would have never guessed to find 12 different ones though. As you'll see in the photo's I've posted there 12 different markings. As a side note there is a single photo of the head marking that is included in my Door & Window Hardware kit. I know some of you guys are pretty serious about head markings so thought this may be of some interest.





For reference this photo shows the head marking that is on the Door & Window Fastener Kit that I sell:





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Neat - thanks for the post!

 

I never really noticed head markings on standard-grade bolts until I bought the model T. I found several Phillips-head screws in the car, but 99% were slotted. I did some digging and found that the Phillips screw was not invented until after the end of Model T production in 1927. They are all gone now. When I hopped a ride in the Ford Tri-motor I noticed several Phillips screws retaining window moldings. The tri-motor was also built in 1927 so the Phillips screws were incorrect for the airplane.

 

Wow, I just learned something while reading up on the Phillips head screw-Canadian Ts are full of square head predecessors known as Robertson screws, but apparently ol’ Henry’s attempt to license, then outright buy Mr. Robertson’s company to speed US production insulted the man so badly that he refused to do business with him, thus slotted screws prevailed here. Fascinating!
Patrick

 

Good Info Todd! Since we do a fair share of Older Corvette Repair/Restoration I keep this Paragon bolt chart on the wall above my desk.

I figure when restoring or even regular service work on a classic vehicle, that if you are going to replace old rusty or missing fasteners, ... you may as well use the correct ones if available. They usually cost the same as hardware store fasteners, sometimes cheaper.

One more note: We always use a coat or two of "Sharkhide" Metal Protectant to keep the finish lasting. Especially important on black oxide fasteners which tend to degrade rapidly.



Larry

 

I had a customer asking about this the other day so thought I'd bring it ttt.

 

I worked at a GM BOP plant in 1972,

Bolts came came from multiple suppliers.

 

Bringing this back to the top . . . . . .

 

A mod should pin this in the right section!

 

I am starting to wonder if automotive purists have special underwear for special occasions, even though no one can see the underwear, the purists know it's there, kind of like all the correct parts, nuts and bolts no one can see! Sorry guys I couldn't resist!

Bob H.

 

You guys are in deep now. It seems you need all 12 different manufactures bolts to be correct.

 

Lol, I like to assemble these cars as "Correct" as the next guy but EVEN IF the reproduction companies such as AMK reproduce a certain bolt they're not going to do all the different head markings GM may have used "back in the day".

I for one am happy with most of the offerings AMK currently reproduces. . . . . The Bolts (in MOST cases) are Correct. They're only going to offer ONE head marking though. Hopefully it's good enough for most guys.

 

Man - that sharkhide is expensive!

 

But it's GOOD and the can does a LOT of items. I've been using it for years. I even did all of the aluminum components on my Tomahawk engine...... heads, intake, timing cover, vacuum pump, block, etc. Really good stuff and very easy to use. For the cast aluminum parts I use one of the wife's emptied hair spray bottles and mist it on........ lasts a LONG time.

 

...any time there's a bolt/screw discussion, I'm reminded of the Flint-only 5/16 X 12 screw used for front-end sheet metal. Duane explained it as Flint being totally under Buick's control whereas BOP was corporate. Beyond grade markings, I don't pay attention to fastener heads. Having a Flint car, I am, however, very aware of thread pitch (use a BOP screw on a Flint car, or vice versa, and break off weld nut). This discussion makes me wonder if being built in Flint has any effect on head markings. Duane...?...

 

Yeah, you get what you pay for Steve!

 

I would say yes to that.

Flint was run by Buick, so they were able to purchase hardware from the companies they wanted.

The GMAD plants did not have that luxury and had to accept whatever hardware corporate sent them.

I never looked at all the different head markings on the bolts, however in the past while working on my cars, I did have my hardware separated between Flint and GMAD.

You would be surprised to see the appearance differences between bumper bracket-frame bolts, and the Bumper to bumper bracket bolts you see at the bottom of the bumpers.

Beyond the hardware thread differences, this really comes into play when you are putting together the engines. All the V-8 motors were built at Flint, so they used Flint hardware.

The funny thing is they often used different hardware for different years.

That is where I usually catch people with mixing and matching parts. Like putting 70 style valve cover bolts on a 71 motor, etc.
Duane