Whether you’re building a custom car or upgrading your daily driver, there are a lot of different options for fasteners. Many times you pick up the bolts you used before, but you also may want to upgrade to something stronger, or even something better looking.
To start you have your standard zinc-plated bolt. You can tell by the 3 ticks at the top that it’s a Grade 5.
Next, you can upgrade to a cadmium-plated Grade 8 bolt or step it up even more to a stainless steel bolt that is resistant to corrosion.
You also have socket cap bolts that take a hex key to drive them. The head is smaller which means you can get them into a tighter spot. They come in different finishes, coarse thread or fine thread, and you can even get them chrome-plated.
Button-head bolts also come in different finishes and threads. These are for use in areas where you don’t want the head to get caught on things and are also driven by a hex key.
If a button-head isn’t low profile enough you can use a countersunk bolt. You need to taper the hole and then the bolt will mount flush with the surface.
An ARP bolt is unique in that it has a 12-point head which requires a 12-point socket. These bolts are super strong and because the heads are so small you can use them when you would normally use a socket-head bolt.
Metric bolts are used in a lot of vehicles built in the mid-80s forward. If you have threads that are tapped into the vehicle, you’ll need to use these. You can tell the difference between a standard and a metric by what’s stamped on the head.
Standard will have lines that indicate the grade whereas the metric uses a number.
Of course, these aren’t the only kinds of bolts out there but it’s a pretty good start on what’s used in automotive applications…